<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva, formerly WebFilings-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.commvault.com/role/AccruedLiabilities" xlink:href="cvlt-20150331.xsd#AccruedLiabilities" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/AccruedLiabilitiesDetail" xlink:href="cvlt-20150331.xsd#AccruedLiabilitiesDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/AccruedLiabilitiesTables" xlink:href="cvlt-20150331.xsd#AccruedLiabilitiesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ActivityForCompanysTwoStockIncentivePlansDetail" xlink:href="cvlt-20150331.xsd#ActivityForCompanysTwoStockIncentivePlansDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/AssumptionsUsedInBlackScholesOptionPricingModelDetail" xlink:href="cvlt-20150331.xsd#AssumptionsUsedInBlackScholesOptionPricingModelDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/Capitalization" xlink:href="cvlt-20150331.xsd#Capitalization" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/CapitalizationDetail" xlink:href="cvlt-20150331.xsd#CapitalizationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/CommitmentsAndContingencies" xlink:href="cvlt-20150331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/CommitmentsAndContingenciesAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#CommitmentsAndContingenciesAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderAllOperatingLeasesDetail" xlink:href="cvlt-20150331.xsd#CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderAllOperatingLeasesDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/CommitmentsAndContingenciesTables" xlink:href="cvlt-20150331.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedBalanceSheets" xlink:href="cvlt-20150331.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="cvlt-20150331.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="cvlt-20150331.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:href="cvlt-20150331.xsd#ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedStatementsOfIncome" xlink:href="cvlt-20150331.xsd#ConsolidatedStatementsOfIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:href="cvlt-20150331.xsd#ConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/DocumentAndEntityInformation" xlink:href="cvlt-20150331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/EmployeeBenefitPlan" xlink:href="cvlt-20150331.xsd#EmployeeBenefitPlan" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/EmployeeBenefitPlanAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#EmployeeBenefitPlanAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxes" xlink:href="cvlt-20150331.xsd#IncomeTaxes" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesComponentsOfDeferredTaxAssetsDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesComponentsOfDeferredTaxAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesComponentsOfIncomeBeforeIncomeTaxesDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesComponentsOfIncomeBeforeIncomeTaxesDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesComponentsOfIncomeTaxExpenseBenefitDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesComponentsOfIncomeTaxExpenseBenefitDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesReconciliationOfAmountsOfUnrecognizedTaxBenefitsDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesReconciliationOfAmountsOfUnrecognizedTaxBenefitsDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesReconciliationOfStatutoryTaxRatesAndEffectiveTaxRatesDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesReconciliationOfStatutoryTaxRatesAndEffectiveTaxRatesDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesScheduleOfTaxYearsSubjectToIncomeTaxExaminationDetail" xlink:href="cvlt-20150331.xsd#IncomeTaxesScheduleOfTaxYearsSubjectToIncomeTaxExaminationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/IncomeTaxesTables" xlink:href="cvlt-20150331.xsd#IncomeTaxesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/NatureOfBusiness" xlink:href="cvlt-20150331.xsd#NatureOfBusiness" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/PropertyAndEquipment" xlink:href="cvlt-20150331.xsd#PropertyAndEquipment" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/PropertyAndEquipmentAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#PropertyAndEquipmentAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/PropertyAndEquipmentDetail" xlink:href="cvlt-20150331.xsd#PropertyAndEquipmentDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/PropertyAndEquipmentTables" xlink:href="cvlt-20150331.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/RestrictedStockUnitActivityDetail" xlink:href="cvlt-20150331.xsd#RestrictedStockUnitActivityDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/RevolvingCreditFacility" xlink:href="cvlt-20150331.xsd#RevolvingCreditFacility" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/RevolvingCreditFacilityDetails" xlink:href="cvlt-20150331.xsd#RevolvingCreditFacilityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:href="cvlt-20150331.xsd#ScheduleIiValuationAndQualifyingAccounts" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/ScheduleIiValuationAndQualifyingAccountsDetail" xlink:href="cvlt-20150331.xsd#ScheduleIiValuationAndQualifyingAccountsDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SegmentInformation" xlink:href="cvlt-20150331.xsd#SegmentInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SegmentInformationAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#SegmentInformationAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SegmentInformationScheduleOfLongLivedAssetsByGeographicAreaDetail" xlink:href="cvlt-20150331.xsd#SegmentInformationScheduleOfLongLivedAssetsByGeographicAreaDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SegmentInformationScheduleOfRevenueByGeographicAreaDetail" xlink:href="cvlt-20150331.xsd#SegmentInformationScheduleOfRevenueByGeographicAreaDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SegmentInformationTables" xlink:href="cvlt-20150331.xsd#SegmentInformationTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnaudited" xlink:href="cvlt-20150331.xsd#SelectedQuarterlyFinancialDataUnaudited" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnauditedDetail" xlink:href="cvlt-20150331.xsd#SelectedQuarterlyFinancialDataUnauditedDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnauditedTables" xlink:href="cvlt-20150331.xsd#SelectedQuarterlyFinancialDataUnauditedTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/StockBasedCompensationExpenseDetail" xlink:href="cvlt-20150331.xsd#StockBasedCompensationExpenseDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/StockPlans" xlink:href="cvlt-20150331.xsd#StockPlans" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/StockPlansAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#StockPlansAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/StockPlansTables" xlink:href="cvlt-20150331.xsd#StockPlansTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesAdditionalInformationDetail" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesAdditionalInformationDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesComputationOfBasicAndDilutedNetIncomePerCommonShareDetail" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesComputationOfBasicAndDilutedNetIncomePerCommonShareDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesDeferredRevenueDetail" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesDeferredRevenueDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesSummaryOfFairValueOfFinancialAssetsDetail" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesSummaryOfFairValueOfFinancialAssetsDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesSummaryOfPotentialOutstandingCommonStockEquivalentsDetail" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesSummaryOfPotentialOutstandingCommonStockEquivalentsDetail" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="cvlt-20150331.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.commvault.com/role/SummaryOfStockOptionsOutstandingUnderPlanAndLtipDetail" xlink:href="cvlt-20150331.xsd#SummaryOfStockOptionsOutstandingUnderPlanAndLtipDetail" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://www.commvault.com/role/AccruedLiabilities" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/AccruedLiabilitiesDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/AccruedLiabilitiesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ActivityForCompanysTwoStockIncentivePlansDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/AssumptionsUsedInBlackScholesOptionPricingModelDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/Capitalization" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/CapitalizationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_8A17B47790AB9CACEE60C9BB7383899B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_8A17B47790AB9CACEE60C9BB7383899B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9E4A714A620049A2C1A6C9BB73830CC1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_8A17B47790AB9CACEE60C9BB7383899B" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9E4A714A620049A2C1A6C9BB73830CC1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_0E756B98C5853F8EB10DC9BB7383D33B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9E4A714A620049A2C1A6C9BB73830CC1" xlink:to="loc_us-gaap_ClassOfStockDomain_0E756B98C5853F8EB10DC9BB7383D33B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_0E756B98C5853F8EB10DC9BB7383D33B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9E4A714A620049A2C1A6C9BB73830CC1" xlink:to="loc_us-gaap_ClassOfStockDomain_0E756B98C5853F8EB10DC9BB7383D33B" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SeriesaJuniorParticipatingPreferredMember" xlink:label="loc_cvlt_SeriesaJuniorParticipatingPreferredMember_F39DDD657EDBBA537A28C9BB7383CDDF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0E756B98C5853F8EB10DC9BB7383D33B" xlink:to="loc_cvlt_SeriesaJuniorParticipatingPreferredMember_F39DDD657EDBBA537A28C9BB7383CDDF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_E6CB4D2BD7157E98F624C9BB73836FC0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_8A17B47790AB9CACEE60C9BB7383899B" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_E6CB4D2BD7157E98F624C9BB73836FC0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_F6E8F7F2EF5C9F2D47C5C9BB73835256_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_E6CB4D2BD7157E98F624C9BB73836FC0" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_F6E8F7F2EF5C9F2D47C5C9BB73835256_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_F6E8F7F2EF5C9F2D47C5C9BB73835256" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_E6CB4D2BD7157E98F624C9BB73836FC0" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_F6E8F7F2EF5C9F2D47C5C9BB73835256" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_CommonStockRepurchaseProgramMember" xlink:label="loc_cvlt_CommonStockRepurchaseProgramMember_7E82EE8FDA1275C0CCBDC9BB73846867" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_F6E8F7F2EF5C9F2D47C5C9BB73835256" xlink:to="loc_cvlt_CommonStockRepurchaseProgramMember_7E82EE8FDA1275C0CCBDC9BB73846867" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_5EB1A912835E4DC0D79BC9BB73844A7C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_8A17B47790AB9CACEE60C9BB7383899B" xlink:to="loc_us-gaap_AwardTypeAxis_5EB1A912835E4DC0D79BC9BB73844A7C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93A9ED3438DE6AEC3342C9BB73848AF2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_5EB1A912835E4DC0D79BC9BB73844A7C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93A9ED3438DE6AEC3342C9BB73848AF2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93A9ED3438DE6AEC3342C9BB73848AF2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_5EB1A912835E4DC0D79BC9BB73844A7C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93A9ED3438DE6AEC3342C9BB73848AF2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_4B5146E6C803AAE18436C9BB73845319" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93A9ED3438DE6AEC3342C9BB73848AF2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_4B5146E6C803AAE18436C9BB73845319" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_F1CDDC163BD187FE9B9BC9BB73844AAB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_F1CDDC163BD187FE9B9BC9BB73844AAB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_B8C1AB88A3DE83FE2AE2C9BB738424E5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_B8C1AB88A3DE83FE2AE2C9BB738424E5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_F19E17BDB4888045B823C9BB7384A91B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_F19E17BDB4888045B823C9BB7384A91B" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock" xlink:label="loc_cvlt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock_EC809378FAFE16FD6B47C9BB7384A4FA" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_NumberOfRightDeclaredAsDividendDistributionForEachOutstandingShareOfCommonStock_EC809378FAFE16FD6B47C9BB7384A4FA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_4530BC0E2D6F6653E72CC9BB7384E57D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_4530BC0E2D6F6653E72CC9BB7384E57D" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_PreferredStockRightsExercisePrice" xlink:label="loc_cvlt_PreferredStockRightsExercisePrice_C03977D858E9AECB0270C9BB7384CE30" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_PreferredStockRightsExercisePrice_C03977D858E9AECB0270C9BB7384CE30" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_PeriodBeforeRightsBecomeExercisable" xlink:label="loc_cvlt_PeriodBeforeRightsBecomeExercisable_4CE766C9559B9299E688C9BB73841F9F" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_PeriodBeforeRightsBecomeExercisable_4CE766C9559B9299E688C9BB73841F9F" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ClassofWarrantorRightExercisableEventMinimumPercentofCommonStockAcquired" xlink:label="loc_cvlt_ClassofWarrantorRightExercisableEventMinimumPercentofCommonStockAcquired_CD4C61731194AE09EB4DC9BB7384339A" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_ClassofWarrantorRightExercisableEventMinimumPercentofCommonStockAcquired_CD4C61731194AE09EB4DC9BB7384339A" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_DescriptionOfExerciseEntitlementOfEachRight" xlink:label="loc_cvlt_DescriptionOfExerciseEntitlementOfEachRight_8684E7B407D75DC2C8E5C9BB73848E68" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_DescriptionOfExerciseEntitlementOfEachRight_8684E7B407D75DC2C8E5C9BB73848E68" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ConditionsUnderWhichRightsBecomeExercisable" xlink:label="loc_cvlt_ConditionsUnderWhichRightsBecomeExercisable_294B4894CA45CC749A89C9BB738488F3" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_ConditionsUnderWhichRightsBecomeExercisable_294B4894CA45CC749A89C9BB738488F3" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_RedemptionPriceOfEachRight" xlink:label="loc_cvlt_RedemptionPriceOfEachRight_505500875885845E9715C9BB7384D180" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_RedemptionPriceOfEachRight_505500875885845E9715C9BB7384D180" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExpirationDateOfRights" xlink:label="loc_cvlt_ExpirationDateOfRights_70559E210C47F056F798C9BB7384FF64" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_cvlt_ExpirationDateOfRights_70559E210C47F056F798C9BB7384FF64" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_C1FA697BA7380A2C301CC9BB73840BD7" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_C1FA697BA7380A2C301CC9BB73840BD7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_5E5B9C004633ACDA98B9C9BB73843884" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_5E5B9C004633ACDA98B9C9BB73843884" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_6D4B1FBE650B069C33BAC9BB738452CD" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_6D4B1FBE650B069C33BAC9BB738452CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_932F9E2F3D4412923F6AC9BB7384E578" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_932F9E2F3D4412923F6AC9BB7384E578" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount_D39CC62AA8B39A644D08C9BB73849AD0" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount_D39CC62AA8B39A644D08C9BB73849AD0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_E12E3A280046D114E6B1C9BB7384A4E7" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_51AFFB377C8BC006B211C9BB7384E071" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_E12E3A280046D114E6B1C9BB7384A4E7" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/CommitmentsAndContingenciesAdditionalInformationDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderAllOperatingLeasesDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedStatementsOfIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_D0FDA059AE6CC8994239217AEA2C4419" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_6A18AB8C840D00EFB191217AEA2CDAC6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_D0FDA059AE6CC8994239217AEA2C4419" xlink:to="loc_us-gaap_StatementTable_6A18AB8C840D00EFB191217AEA2CDAC6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3918673F13BC34922DDA217AEA2C6026" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_6A18AB8C840D00EFB191217AEA2CDAC6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3918673F13BC34922DDA217AEA2C6026" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3918673F13BC34922DDA217AEA2C6026" xlink:to="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3918673F13BC34922DDA217AEA2C6026" xlink:to="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_58EE2E3AC27159D52ECA217AEA2C3DD8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:to="loc_us-gaap_CommonStockMember_58EE2E3AC27159D52ECA217AEA2C3DD8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_186950A12B9C0E735DA0217AEA2CB760" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_186950A12B9C0E735DA0217AEA2CB760" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_CB0234CE308289A42F20217AEA2CE044" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:to="loc_us-gaap_RetainedEarningsMember_CB0234CE308289A42F20217AEA2CE044" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_A524F1D135C8EF1C2B62217AEA2CB1DD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_159C791C7B976CD41072217AEA2CBE77" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_A524F1D135C8EF1C2B62217AEA2CB1DD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D0FDA059AE6CC8994239217AEA2C4419" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_04982C09EB5CBAA312CE217AEA2C9149" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_SharesOutstanding_04982C09EB5CBAA312CE217AEA2C9149" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_F7227497B7940FF65DE5217AEA2C2FE9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_StockholdersEquity_F7227497B7940FF65DE5217AEA2C2FE9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2984AED89C83D2C6BBE9217AEA2D6ECD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2984AED89C83D2C6BBE9217AEA2D6ECD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_2FDA4FF0EFA98D287648217AEA2DB3BD" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation_2FDA4FF0EFA98D287648217AEA2DB3BD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_434B3F5C1DF7C1D6CA38217AEA2D8F92" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_434B3F5C1DF7C1D6CA38217AEA2D8F92" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_AE9CADB85DEB91FAE307217AEA2D737C" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_AE9CADB85DEB91FAE307217AEA2D737C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_3CA0D018872735CB6C7B217AEA2D964C" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_3CA0D018872735CB6C7B217AEA2D964C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_1A2F7EF40E9EF5E8DFB8217AEA2D0494" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_1A2F7EF40E9EF5E8DFB8217AEA2D0494" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_40F20FEB1DEE6E00CE64217AEA2DD5DA" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_NetIncomeLoss_40F20FEB1DEE6E00CE64217AEA2DD5DA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_F6D329F48A6F147938E7217AEA2D240A" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_CB0996EEF06AE86E4F39217AEA2C093C" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_F6D329F48A6F147938E7217AEA2D240A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/EmployeeBenefitPlan" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/EmployeeBenefitPlanAdditionalInformationDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxes" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardLineItems" xlink:label="loc_us-gaap_TaxCreditCarryforwardLineItems_5AA07AD19BCE30785177309160020B0C" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardTable" xlink:label="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_5AA07AD19BCE30785177309160020B0C" xlink:to="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_62E8ED9B8F3D6807268730916001DA4D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_62E8ED9B8F3D6807268730916001DA4D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_62E8ED9B8F3D6807268730916001DA4D" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_62E8ED9B8F3D6807268730916001DA4D" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherLiabilitiesMember" xlink:label="loc_us-gaap_OtherLiabilitiesMember_AD9C9DF7FDA71FD41FE7309160013B13" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8" xlink:to="loc_us-gaap_OtherLiabilitiesMember_AD9C9DF7FDA71FD41FE7309160013B13" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_DeferredTaxAssetsMember" xlink:label="loc_cvlt_DeferredTaxAssetsMember_FA86BF49902E3AB8669C30916001E601" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_3A222E3FA6DEFA307CEC30916001FAB8" xlink:to="loc_cvlt_DeferredTaxAssetsMember_FA86BF49902E3AB8669C30916001E601" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_B185C4E716CD061B333E30916001473A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_B185C4E716CD061B333E30916001473A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_B185C4E716CD061B333E30916001473A" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_B185C4E716CD061B333E30916001473A" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_8ADE1A21110C274F869D3091600150F4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_8ADE1A21110C274F869D3091600150F4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_3E5A8C04F55D9CF1C77C309160029EDB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76" xlink:to="loc_us-gaap_ForeignCountryMember_3E5A8C04F55D9CF1C77C309160029EDB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_9BC9DC12BAB004555B093091600270C4" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_728896852396CF0BA9D930916001AF76" xlink:to="loc_us-gaap_DomesticCountryMember_9BC9DC12BAB004555B093091600270C4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_3D14D95C335745AE87B030916002048B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_3D14D95C335745AE87B030916002048B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_85DC89EFFE623A15BF3E30916002326D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_3D14D95C335745AE87B030916002048B" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_85DC89EFFE623A15BF3E30916002326D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_85DC89EFFE623A15BF3E30916002326D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_3D14D95C335745AE87B030916002048B" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_85DC89EFFE623A15BF3E30916002326D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchMember" xlink:label="loc_us-gaap_ResearchMember_0F336BB9C4468E0495E7309160027354" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_85DC89EFFE623A15BF3E30916002326D" xlink:to="loc_us-gaap_ResearchMember_0F336BB9C4468E0495E7309160027354" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_28C5C1C18FAB9FAD932B30916002A440" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable_4B0D61F01FE52A92A7E830916001572A" xlink:to="loc_us-gaap_RangeAxis_28C5C1C18FAB9FAD932B30916002A440" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_28C5C1C18FAB9FAD932B30916002A440" xlink:to="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_28C5C1C18FAB9FAD932B30916002A440" xlink:to="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_F766E3FE93369AFD943730916002EDA3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554" xlink:to="loc_us-gaap_MinimumMember_F766E3FE93369AFD943730916002EDA3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_F08EB7D5D47B48C5C344309160021E60" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_55D69ED26ECBBD0508FD309160028554" xlink:to="loc_us-gaap_MaximumMember_F08EB7D5D47B48C5C344309160021E60" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_779C18FCBCD00596257D309160025B3C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_5AA07AD19BCE30785177309160020B0C" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_779C18FCBCD00596257D309160025B3C" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_TaxCreditCarryforwardExpirationYear" xlink:label="loc_cvlt_TaxCreditCarryforwardExpirationYear_583F37A7AFF52A64184D3091600286D7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_5AA07AD19BCE30785177309160020B0C" xlink:to="loc_cvlt_TaxCreditCarryforwardExpirationYear_583F37A7AFF52A64184D3091600286D7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedAbstract" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedAbstract_039E94F8A002D8981B9330916002F2F2" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems_5AA07AD19BCE30785177309160020B0C" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedAbstract_039E94F8A002D8981B9330916002F2F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_143A690BD1E60E51152730916002A2F0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedAbstract_039E94F8A002D8981B9330916002F2F2" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_143A690BD1E60E51152730916002A2F0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_931B7F8D30B8402A4D63309160020DF8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccruedAbstract_039E94F8A002D8981B9330916002F2F2" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_931B7F8D30B8402A4D63309160020DF8" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesComponentsOfDeferredTaxAssetsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesComponentsOfIncomeBeforeIncomeTaxesDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesComponentsOfIncomeTaxExpenseBenefitDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesReconciliationOfAmountsOfUnrecognizedTaxBenefitsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesReconciliationOfStatutoryTaxRatesAndEffectiveTaxRatesDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesScheduleOfTaxYearsSubjectToIncomeTaxExaminationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExaminationLineItems" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_A4F73BD7CFE573F3F661309178FD5130" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExaminationTable" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_FA97F840C5966B716463309178FCF840" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_A4F73BD7CFE573F3F661309178FD5130" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_FA97F840C5966B716463309178FCF840" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_4459B3E78A269CBE4158309178FC5919" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_FA97F840C5966B716463309178FCF840" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_4459B3E78A269CBE4158309178FC5919" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_4459B3E78A269CBE4158309178FC5919" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_4459B3E78A269CBE4158309178FC5919" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_1573D897D642D1451211309178FC5DFC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A" xlink:to="loc_us-gaap_DomesticCountryMember_1573D897D642D1451211309178FC5DFC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_D36C25D8ED94D3BE8CEE309178FC70B8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_D36C25D8ED94D3BE8CEE309178FC70B8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_B476C9C1E036DE71E7FE309178FCD488" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_6021E6281A5BCC79407E309178FC053A" xlink:to="loc_us-gaap_ForeignCountryMember_B476C9C1E036DE71E7FE309178FCD488" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_90B239AB337A3739DF34309178FCC0CF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_FA97F840C5966B716463309178FCF840" xlink:to="loc_us-gaap_RangeAxis_90B239AB337A3739DF34309178FCC0CF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_90B239AB337A3739DF34309178FCC0CF" xlink:to="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_90B239AB337A3739DF34309178FCC0CF" xlink:to="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_437260DC18AE9EC6CFB0309178FC7E47" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6" xlink:to="loc_us-gaap_MinimumMember_437260DC18AE9EC6CFB0309178FC7E47" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_D18147F53DB35E64F6DA309178FCD450" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_7F5C7BCA56F95ED515BF309178FCACD6" xlink:to="loc_us-gaap_MaximumMember_D18147F53DB35E64F6DA309178FCD450" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OpenTaxYear" xlink:label="loc_us-gaap_OpenTaxYear_2D66F350082C67B982B4309178FD91E8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_A4F73BD7CFE573F3F661309178FD5130" xlink:to="loc_us-gaap_OpenTaxYear_2D66F350082C67B982B4309178FD91E8" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/IncomeTaxesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/NatureOfBusiness" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/PropertyAndEquipment" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/PropertyAndEquipmentAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42D00E9004621D05DE372AF3C2A572A9" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_AF88D1AA6DDBC2D1D8F52AF3C2A4C53A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42D00E9004621D05DE372AF3C2A572A9" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_AF88D1AA6DDBC2D1D8F52AF3C2A4C53A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_415A98B15C6AE76BCCDC2AF3C2A58679" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_AF88D1AA6DDBC2D1D8F52AF3C2A4C53A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_415A98B15C6AE76BCCDC2AF3C2A58679" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_612DA5FF243743AC76D42AF3C2A5032D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_415A98B15C6AE76BCCDC2AF3C2A58679" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_612DA5FF243743AC76D42AF3C2A5032D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_612DA5FF243743AC76D42AF3C2A5032D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_415A98B15C6AE76BCCDC2AF3C2A58679" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_612DA5FF243743AC76D42AF3C2A5032D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_9DBEAD9D29921CB404292AF3C2A5D4C0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_612DA5FF243743AC76D42AF3C2A5032D" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_9DBEAD9D29921CB404292AF3C2A5D4C0" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_AcceleratedDepreciation" xlink:label="loc_cvlt_AcceleratedDepreciation_2BFAF50383884B06C5C32AF3C2A5BC4D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42D00E9004621D05DE372AF3C2A572A9" xlink:to="loc_cvlt_AcceleratedDepreciation_2BFAF50383884B06C5C32AF3C2A5BC4D" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_LIabilityforContractTerminationn" xlink:label="loc_cvlt_LIabilityforContractTerminationn_CA92BA1D60CFE15B22C32AF3C2A5AB3F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42D00E9004621D05DE372AF3C2A572A9" xlink:to="loc_cvlt_LIabilityforContractTerminationn_CA92BA1D60CFE15B22C32AF3C2A5AB3F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_23095B71E71A73D5882C2AF3C5EBEC17" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_42D00E9004621D05DE372AF3C2A572A9" xlink:to="loc_us-gaap_Depreciation_23095B71E71A73D5882C2AF3C5EBEC17" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/PropertyAndEquipmentDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_624F0E63464E10FB2950C9BB739E4AB1" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3624AAA325B6D5A00FAEC9BB739D427B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_624F0E63464E10FB2950C9BB739E4AB1" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3624AAA325B6D5A00FAEC9BB739D427B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_43422F1ABF29492321A7C9BB739D0317" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3624AAA325B6D5A00FAEC9BB739D427B" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_43422F1ABF29492321A7C9BB739D0317" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_43422F1ABF29492321A7C9BB739D0317" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_43422F1ABF29492321A7C9BB739D0317" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LandMember" xlink:label="loc_us-gaap_LandMember_CD2CAF25BC7B90E860EBC9BB739DC2A2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_LandMember_CD2CAF25BC7B90E860EBC9BB739DC2A2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BuildingMember" xlink:label="loc_us-gaap_BuildingMember_3EB799B20FA8E949E385C9BB739D30EC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_BuildingMember_3EB799B20FA8E949E385C9BB739D30EC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember_B4734D9BD3A25A12C4D3C9BB739DF532" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_ComputerEquipmentMember_B4734D9BD3A25A12C4D3C9BB739DF532" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_405509258922298E05AAC9BB739DDC47" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_405509258922298E05AAC9BB739DDC47" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_657E77E032C65D70854AC9BB739D2A2A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_657E77E032C65D70854AC9BB739D2A2A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_29E71AAFED7D0AB94E0FC9BB739EA841" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_29E71AAFED7D0AB94E0FC9BB739EA841" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember_9247E64991700F69E70BC9BB739E4D7F" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_3C13487C15FA6F5B74A6C9BB739DACB9" xlink:to="loc_us-gaap_ConstructionInProgressMember_9247E64991700F69E70BC9BB739E4D7F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_600D92282424EC85F4E1C9BB739ED570" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_624F0E63464E10FB2950C9BB739E4AB1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_600D92282424EC85F4E1C9BB739ED570" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_BC1738BADF68F51BE0E0C9BB739ED8A4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_624F0E63464E10FB2950C9BB739E4AB1" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_BC1738BADF68F51BE0E0C9BB739ED8A4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_31CB5C092B7FBE8E5C22C9BB739EEBC7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_624F0E63464E10FB2950C9BB739E4AB1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_31CB5C092B7FBE8E5C22C9BB739EEBC7" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/RestrictedStockUnitActivityDetail" xlink:type="extended">
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsLineItems" xlink:label="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsLineItems_CF96134954D2C4107A22C400AC38AD07" xlink:type="locator" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsTable" xlink:label="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsTable_939D0B2B5CCB1F074F7CC400AC384E14" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsLineItems_CF96134954D2C4107A22C400AC38AD07" xlink:to="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsTable_939D0B2B5CCB1F074F7CC400AC384E14" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_74B1879C6D4E5CE95E68C400AC385235" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsTable_939D0B2B5CCB1F074F7CC400AC384E14" xlink:to="loc_us-gaap_AwardTypeAxis_74B1879C6D4E5CE95E68C400AC385235" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0357C84EC3E372FA7339C400AC38E5FB_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_74B1879C6D4E5CE95E68C400AC385235" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0357C84EC3E372FA7339C400AC38E5FB_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0357C84EC3E372FA7339C400AC38E5FB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_74B1879C6D4E5CE95E68C400AC385235" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0357C84EC3E372FA7339C400AC38E5FB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_01B7CA69564B4C1CD0D2C400AC38956C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0357C84EC3E372FA7339C400AC38E5FB" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_01B7CA69564B4C1CD0D2C400AC38956C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsLineItems_CF96134954D2C4107A22C400AC38AD07" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_01818D9E9EB115A7AC48C400AC383E1D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_01818D9E9EB115A7AC48C400AC383E1D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_4FC30F622FD045566741C400AC39FCDB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_4FC30F622FD045566741C400AC39FCDB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_DC51B891EC680622A3C2C400AC396534" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_DC51B891EC680622A3C2C400AC396534" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_76B22CD2508BA34CB4DBC400AC39A93B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_2CBBE2CF698C464D2E8AC400AC3892FA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_76B22CD2508BA34CB4DBC400AC39A93B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRestrictedStockUnitsLineItems_CF96134954D2C4107A22C400AC38AD07" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_52F8D601E3E9AF64E713C400AC396BFC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_52F8D601E3E9AF64E713C400AC396BFC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4E02CAAF15C241DC0E50C400AC39E496" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_4E02CAAF15C241DC0E50C400AC39E496" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_6711D5166674F4F40166C400AC3915DA" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_6711D5166674F4F40166C400AC3915DA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5F2CB9D66844B266EC67C400AC3976C1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_695F9F28203AD408E7F4C400AC395F81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5F2CB9D66844B266EC67C400AC3976C1" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/RevolvingCreditFacility" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/RevolvingCreditFacilityDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_AFE7BE83AE47C8AE73582F055EF596B3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_AFE7BE83AE47C8AE73582F055EF596B3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_4FA9466DCEA3BEFF6D292F055EF5ACF2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_AFE7BE83AE47C8AE73582F055EF596B3" xlink:to="loc_us-gaap_CreditFacilityAxis_4FA9466DCEA3BEFF6D292F055EF5ACF2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_FA0E7D2490AB69D72A652F055EF5503B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_4FA9466DCEA3BEFF6D292F055EF5ACF2" xlink:to="loc_us-gaap_CreditFacilityDomain_FA0E7D2490AB69D72A652F055EF5503B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_FA0E7D2490AB69D72A652F055EF5503B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_4FA9466DCEA3BEFF6D292F055EF5ACF2" xlink:to="loc_us-gaap_CreditFacilityDomain_FA0E7D2490AB69D72A652F055EF5503B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_4CC28A066681C72D033D2F055EF54A37" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_FA0E7D2490AB69D72A652F055EF5503B" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_4CC28A066681C72D033D2F055EF54A37" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_288B57F4B5679878ED482F055EF55574" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_AFE7BE83AE47C8AE73582F055EF596B3" xlink:to="loc_us-gaap_VariableRateAxis_288B57F4B5679878ED482F055EF55574" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_226832BF795F27CC9E7F2F055EF6FF18_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_288B57F4B5679878ED482F055EF55574" xlink:to="loc_us-gaap_VariableRateDomain_226832BF795F27CC9E7F2F055EF6FF18_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_226832BF795F27CC9E7F2F055EF6FF18" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_288B57F4B5679878ED482F055EF55574" xlink:to="loc_us-gaap_VariableRateDomain_226832BF795F27CC9E7F2F055EF6FF18" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_C08B60B1170A0B53191A2F055EF65EE4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_226832BF795F27CC9E7F2F055EF6FF18" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_C08B60B1170A0B53191A2F055EF65EE4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_1192A01C4BCEC1E000B52F055EF606D1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_DebtInstrumentTerm_1192A01C4BCEC1E000B52F055EF606D1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6D1CF84136C1C72BD32B2F055EF6DB35" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6D1CF84136C1C72BD32B2F055EF6DB35" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_9068BB5B713874A859882F055EF6C847" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_9068BB5B713874A859882F055EF6C847" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_752D3B230B0992C4354C2F055EF65491" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_752D3B230B0992C4354C2F055EF65491" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_FA07FBB7A3B6D1FBBD592F055EF694E0" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_FA07FBB7A3B6D1FBBD592F055EF694E0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_1514CDD26170C88565092F055EF615E3" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_91D9D3566A9FB1D48ED62F055EF62F56" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_1514CDD26170C88565092F055EF615E3" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/ScheduleIiValuationAndQualifyingAccountsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_988753149D9B7874444E217AE935B7C5" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsDisclosureTable" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CFC8C93460D8BCCE1251217AE9351D07" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_988753149D9B7874444E217AE935B7C5" xlink:to="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CFC8C93460D8BCCE1251217AE9351D07" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_E0477D84B584AFE19465217AE935731D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureTable_CFC8C93460D8BCCE1251217AE9351D07" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_E0477D84B584AFE19465217AE935731D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_E0477D84B584AFE19465217AE935731D" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_E0477D84B584AFE19465217AE935731D" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsMember" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsMember_61C5967A6E1EA2B37583217AE935461E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsMember_61C5967A6E1EA2B37583217AE935461E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_0A9176737950DB1A8740217AE9352D72" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_3FE46495F62BEAE3143A217AE935126D" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_0A9176737950DB1A8740217AE9352D72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_114BAE69318E26A9E93A217AE93520A9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAndQualifyingAccountsDisclosureLineItems_988753149D9B7874444E217AE935B7C5" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_114BAE69318E26A9E93A217AE93520A9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_C399A5A4E3447367219F217AE936A84F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_114BAE69318E26A9E93A217AE93520A9" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_C399A5A4E3447367219F217AE936A84F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_0B8FBBED8F35B6E110E3217AE9360D5F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_114BAE69318E26A9E93A217AE93520A9" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_0B8FBBED8F35B6E110E3217AE9360D5F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_3D6AB347658F1864C2A0217AE9372EFD" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_114BAE69318E26A9E93A217AE93520A9" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_3D6AB347658F1864C2A0217AE9372EFD" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SegmentInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SegmentInformationAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_6C771B74AE2CE416C7AB309408C250BE" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_858834D970D203A442BA309408C26A7A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6C771B74AE2CE416C7AB309408C250BE" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_858834D970D203A442BA309408C26A7A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_C5E11D21637C59D1BB11309408C2DD64" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_858834D970D203A442BA309408C26A7A" xlink:to="loc_us-gaap_StatementGeographicalAxis_C5E11D21637C59D1BB11309408C2DD64" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_9750082B57E1763FDE32309408C2C88C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_C5E11D21637C59D1BB11309408C2DD64" xlink:to="loc_us-gaap_SegmentGeographicalDomain_9750082B57E1763FDE32309408C2C88C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_9750082B57E1763FDE32309408C2C88C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_C5E11D21637C59D1BB11309408C2DD64" xlink:to="loc_us-gaap_SegmentGeographicalDomain_9750082B57E1763FDE32309408C2C88C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_EB4A26AEA5AD1F9B7AC6309408C246CF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_9750082B57E1763FDE32309408C2C88C" xlink:to="loc_country_US_EB4A26AEA5AD1F9B7AC6309408C246CF" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_EntityWideRevenueCriteriaForMajorCustomerPercentageOfRevenue" xlink:label="loc_cvlt_EntityWideRevenueCriteriaForMajorCustomerPercentageOfRevenue_1EC9A7EBDDA65E956FB3309408C28A6F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6C771B74AE2CE416C7AB309408C250BE" xlink:to="loc_cvlt_EntityWideRevenueCriteriaForMajorCustomerPercentageOfRevenue_1EC9A7EBDDA65E956FB3309408C28A6F" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_EntityWideLongLivedAssetsCriteriaForMajorCustomerPercentageOfLongLivedAssets" xlink:label="loc_cvlt_EntityWideLongLivedAssetsCriteriaForMajorCustomerPercentageOfLongLivedAssets_A553BB3F405768F7828D309408C2E698" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6C771B74AE2CE416C7AB309408C250BE" xlink:to="loc_cvlt_EntityWideLongLivedAssetsCriteriaForMajorCustomerPercentageOfLongLivedAssets_A553BB3F405768F7828D309408C2E698" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SegmentInformationScheduleOfLongLivedAssetsByGeographicAreaDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems" xlink:label="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_D09DE33E02863C41C51E30942985CFFD" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_E6ADFB4FE4307F6455E0309429857806" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_D09DE33E02863C41C51E30942985CFFD" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_E6ADFB4FE4307F6455E0309429857806" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_F360A246CD121C7BDDD23094298584ED" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_E6ADFB4FE4307F6455E0309429857806" xlink:to="loc_us-gaap_StatementGeographicalAxis_F360A246CD121C7BDDD23094298584ED" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_F360A246CD121C7BDDD23094298584ED" xlink:to="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_F360A246CD121C7BDDD23094298584ED" xlink:to="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_34B982AFDAF3A943D022309429859751" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F" xlink:to="loc_country_US_34B982AFDAF3A943D022309429859751" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_OtherForeignCountriesMember" xlink:label="loc_cvlt_OtherForeignCountriesMember_B4BBD7FDE6F9FE2CDDFF30942985D439" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_0F736DFBA6B1EDE475DB30942985274F" xlink:to="loc_cvlt_OtherForeignCountriesMember_B4BBD7FDE6F9FE2CDDFF30942985D439" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NoncurrentAssets" xlink:label="loc_us-gaap_NoncurrentAssets_E41BCD855E665AA6BA9C309429850085" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_D09DE33E02863C41C51E30942985CFFD" xlink:to="loc_us-gaap_NoncurrentAssets_E41BCD855E665AA6BA9C309429850085" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SegmentInformationScheduleOfRevenueByGeographicAreaDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_A934C736B5A68AEAF88E30941666FB6E" xlink:type="locator" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfLongLivedAssetsByGeographicalAreasTable" xlink:label="loc_cvlt_ScheduleOfLongLivedAssetsByGeographicalAreasTable_79DF0F27DC21F484CFF7309416667CA3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_A934C736B5A68AEAF88E30941666FB6E" xlink:to="loc_cvlt_ScheduleOfLongLivedAssetsByGeographicalAreasTable_79DF0F27DC21F484CFF7309416667CA3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_D36CD1DBF6C2F695FE45309416666B0F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_ScheduleOfLongLivedAssetsByGeographicalAreasTable_79DF0F27DC21F484CFF7309416667CA3" xlink:to="loc_us-gaap_StatementGeographicalAxis_D36CD1DBF6C2F695FE45309416666B0F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_D36CD1DBF6C2F695FE45309416666B0F" xlink:to="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_D36CD1DBF6C2F695FE45309416666B0F" xlink:to="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_869717FDFD10F39D6D6630941666BEBD" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04" xlink:to="loc_country_US_869717FDFD10F39D6D6630941666BEBD" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_OtherForeignCountriesMember" xlink:label="loc_cvlt_OtherForeignCountriesMember_58C0F123519119AAF087309416662BA7" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_F838725B59E7F079F59130941666CF04" xlink:to="loc_cvlt_OtherForeignCountriesMember_58C0F123519119AAF087309416662BA7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_09B9FE0F1922A6987BA930941666B894" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_A934C736B5A68AEAF88E30941666FB6E" xlink:to="loc_us-gaap_Revenues_09B9FE0F1922A6987BA930941666B894" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SegmentInformationTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnaudited" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnauditedDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SelectedQuarterlyFinancialDataUnauditedTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/StockBasedCompensationExpenseDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_DC3C06C0156388FA1A6EC9BB73620F62" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_B790DD02891B5991E200C9BB7362BB3C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_DC3C06C0156388FA1A6EC9BB73620F62" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_B790DD02891B5991E200C9BB7362BB3C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_5669851A610A874EB3C9C9BB7362EE16" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_B790DD02891B5991E200C9BB7362BB3C" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_5669851A610A874EB3C9C9BB7362EE16" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5669851A610A874EB3C9C9BB7362EE16" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5669851A610A874EB3C9C9BB7362EE16" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_CostOfServicesRevenueMember" xlink:label="loc_cvlt_CostOfServicesRevenueMember_CA73CC7A75B5608A1B34C9BB7362DF28" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:to="loc_cvlt_CostOfServicesRevenueMember_CA73CC7A75B5608A1B34C9BB7362DF28" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_FD5A47889BB0FB6C3BBEC9BB73627D38" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_FD5A47889BB0FB6C3BBEC9BB73627D38" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_48032D21BDFDC267608EC9BB7362117C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_48032D21BDFDC267608EC9BB7362117C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_34F60754767FD1D01C7EC9BB73624C24" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_F2FEFA1AA4E598BC47D7C9BB7362C48A" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_34F60754767FD1D01C7EC9BB73624C24" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_4E24EC8DAE6DCE14676DC9BB73624176" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_DC3C06C0156388FA1A6EC9BB73620F62" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_4E24EC8DAE6DCE14676DC9BB73624176" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/StockPlans" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/StockPlansAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateAxis" xlink:label="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateAxis_81EA0A6239A9CE025BDF217AE9D1F444" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:to="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateAxis_81EA0A6239A9CE025BDF217AE9D1F444" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain" xlink:label="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateAxis_81EA0A6239A9CE025BDF217AE9D1F444" xlink:to="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C_default" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain" xlink:label="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateAxis_81EA0A6239A9CE025BDF217AE9D1F444" xlink:to="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_NineteenNinetySixStockOptionPlanMember" xlink:label="loc_cvlt_NineteenNinetySixStockOptionPlanMember_5F85FF614B9E7EC2F162217AE9D1DC23" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C" xlink:to="loc_cvlt_NineteenNinetySixStockOptionPlanMember_5F85FF614B9E7EC2F162217AE9D1DC23" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_TwoThousandSixLongTermStockIncentivePlanMember" xlink:label="loc_cvlt_TwoThousandSixLongTermStockIncentivePlanMember_D275E0CA7DEF8E8B4A3B217AE9D109BC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardByGrantDateDomain_9792437E19252C8BF5C8217AE9D1666C" xlink:to="loc_cvlt_TwoThousandSixLongTermStockIncentivePlanMember_D275E0CA7DEF8E8B4A3B217AE9D109BC" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNamesAxis" xlink:label="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNamesAxis_FDEB23547E5D8C9F78F0217AE9D1CAB9" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:to="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNamesAxis_FDEB23547E5D8C9F78F0217AE9D1CAB9" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain" xlink:label="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNamesAxis_FDEB23547E5D8C9F78F0217AE9D1CAB9" xlink:to="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929_default" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain" xlink:label="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNamesAxis_FDEB23547E5D8C9F78F0217AE9D1CAB9" xlink:to="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_StockIncentivePlanMember" xlink:label="loc_cvlt_StockIncentivePlanMember_C9F7110E65A440552392217AE9D1EB50" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929" xlink:to="loc_cvlt_StockIncentivePlanMember_C9F7110E65A440552392217AE9D1EB50" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_EquityAwardsMember" xlink:label="loc_cvlt_EquityAwardsMember_5FA6EB98BBAF84235043217AE9D11077" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlansNameDomain_250AACE64C30BDD7778E217AE9D10929" xlink:to="loc_cvlt_EquityAwardsMember_5FA6EB98BBAF84235043217AE9D11077" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_30F9A329F00886F05ACC217AE9D1C540" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:to="loc_us-gaap_RangeAxis_30F9A329F00886F05ACC217AE9D1C540" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_30F9A329F00886F05ACC217AE9D1C540" xlink:to="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_30F9A329F00886F05ACC217AE9D1C540" xlink:to="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_4D97D536EC577B069E94217AE9D13BBA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D" xlink:to="loc_us-gaap_MinimumMember_4D97D536EC577B069E94217AE9D13BBA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_7C3CC8375C38641D4F3D217AE9D1A317" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_54F79505C3DEAE57CFCC217AE9D1910D" xlink:to="loc_us-gaap_MaximumMember_7C3CC8375C38641D4F3D217AE9D1A317" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_B7C9F6CB71C53E434CF0217AE9D143E7" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0F7416F7012F474C68F1217AE9D143CC" xlink:to="loc_us-gaap_AwardTypeAxis_B7C9F6CB71C53E434CF0217AE9D143E7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_B7C9F6CB71C53E434CF0217AE9D143E7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_B7C9F6CB71C53E434CF0217AE9D143E7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_PerformanceStockOptionsMember" xlink:label="loc_cvlt_PerformanceStockOptionsMember_0203290820B728D4DBA62194B03F01BC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451" xlink:to="loc_cvlt_PerformanceStockOptionsMember_0203290820B728D4DBA62194B03F01BC" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_PerformanceRestrictedStockUnitsMember" xlink:label="loc_cvlt_PerformanceRestrictedStockUnitsMember_1BBA1DFBF61158C711462195590AE2A1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451" xlink:to="loc_cvlt_PerformanceRestrictedStockUnitsMember_1BBA1DFBF61158C711462195590AE2A1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeStockMember" xlink:label="loc_us-gaap_EmployeeStockMember_926D252B6D1BAC1CF9A2217AE9D2668E" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6E1E3766794DDD8C7BA4217AE9D17451" xlink:to="loc_us-gaap_EmployeeStockMember_926D252B6D1BAC1CF9A2217AE9D2668E" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardStockIncentivePlans" xlink:label="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardStockIncentivePlans_CDD89C8FC521005F942D217AE9D2BF90" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardStockIncentivePlans_CDD89C8FC521005F942D217AE9D2BF90" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7ED409FB3EA481DAC4B9217AE9D2D0BA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_7ED409FB3EA481DAC4B9217AE9D2D0BA" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationTerm" xlink:label="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationTerm_A1197EC9546D8A6D0C40217AE9D2714B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationTerm_A1197EC9546D8A6D0C40217AE9D2714B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_72DFB48C406731E01B8B217AE9D2F4E6" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_72DFB48C406731E01B8B217AE9D2F4E6" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantIsIncreasedIfApplicable" xlink:label="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantIsIncreasedIfApplicable_4445B53C5080FBE96938217AE9D27CDF" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantIsIncreasedIfApplicable_4445B53C5080FBE96938217AE9D27CDF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_A86F8BE4D8CA9B2CA0B2217AE9D22E7F" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_A86F8BE4D8CA9B2CA0B2217AE9D22E7F" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue" xlink:label="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue_15064B14167D9FF4C38B217AE9D201DB" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue_15064B14167D9FF4C38B217AE9D201DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1EACF2887C10E1D9F6D9217AE9D21580" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1EACF2887C10E1D9F6D9217AE9D21580" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1C94B93FB51412B1547A217AE9D2C892" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_1C94B93FB51412B1547A217AE9D2C892" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_100953CC29C1AAEF55BD217AE9D2489F" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_100953CC29C1AAEF55BD217AE9D2489F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_29257FEDA727A12F9AAA217AE9D2E480" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_29257FEDA727A12F9AAA217AE9D2E480" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_FairValueOfRestrictedStockUnitsVestedTotal" xlink:label="loc_cvlt_FairValueOfRestrictedStockUnitsVestedTotal_CED027B7E24F99FD0A56217AE9D2043A" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_FairValueOfRestrictedStockUnitsVestedTotal_CED027B7E24F99FD0A56217AE9D2043A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_F971FD1D9031B5FF4873217AE9D2A69E" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_F971FD1D9031B5FF4873217AE9D2A69E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_65C0D565C1243AE6A711217AE9D2CD44" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_65C0D565C1243AE6A711217AE9D2CD44" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_FCD9CA09344398849854217AE9D26A89" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_FCD9CA09344398849854217AE9D26A89" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardOfferingPeriod" xlink:label="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardOfferingPeriod_922350E38D1E165DE07D217AE9D24631" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardOfferingPeriod_922350E38D1E165DE07D217AE9D24631" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_4C53C5E21D159D93E17F217AE9D33C20" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_4C53C5E21D159D93E17F217AE9D33C20" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumAnnualPurchasesPerEmployeeAmount" xlink:label="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumAnnualPurchasesPerEmployeeAmount_7A91E376208919588967217AE9D35BF7" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardMaximumAnnualPurchasesPerEmployeeAmount_7A91E376208919588967217AE9D35BF7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_E212073B061330BBA8D4217AE9D355A3" xlink:type="locator" />
    <definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_E212073B061330BBA8D4217AE9D355A3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="loc_us-gaap_ProceedsFromStockPlans_99DB8305CF759B72BA7E217AE9D3AE5A" xlink:type="locator" />
    <definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_ProceedsFromStockPlans_99DB8305CF759B72BA7E217AE9D3AE5A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_E1E00180C2AA9D683760217AE9D38179" xlink:type="locator" />
    <definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_E1E00180C2AA9D683760217AE9D38179" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardExpenseRecognitionPeriod" xlink:label="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardExpenseRecognitionPeriod_E97D55C57E10A1AB97B2217AE9D3069D" xlink:type="locator" />
    <definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_D4DCDC8C81B94CDD8919217AE9D299FD" xlink:to="loc_cvlt_SharebasedCompensationArrangementbySharebasedPaymentAwardExpenseRecognitionPeriod_E97D55C57E10A1AB97B2217AE9D3069D" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/StockPlansTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesAdditionalInformationDetail" xlink:type="extended">
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SummaryOfSignificantAccountingPoliciesLineItems" xlink:label="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:type="locator" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SummaryOfSignificantAccountingPoliciesTable" xlink:label="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_10AD2B30F56F6A15F1B62EE352C583C5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:to="loc_dei_LegalEntityAxis_10AD2B30F56F6A15F1B62EE352C583C5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_10AD2B30F56F6A15F1B62EE352C583C5" xlink:to="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_10AD2B30F56F6A15F1B62EE352C583C5" xlink:to="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ArrowMember" xlink:label="loc_cvlt_ArrowMember_922598CFF920F42727242EE352C596E4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7" xlink:to="loc_cvlt_ArrowMember_922598CFF920F42727242EE352C596E4" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_HitachiDataSystemsHDSMember" xlink:label="loc_cvlt_HitachiDataSystemsHDSMember_EBA7F88C6D036450FAB32EE352C546C0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_E27D872A7F875C6F01E32EE352C5CDF7" xlink:to="loc_cvlt_HitachiDataSystemsHDSMember_EBA7F88C6D036450FAB32EE352C546C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9BAD82CCEB142A93F5FC2EE352C5AC17" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9BAD82CCEB142A93F5FC2EE352C5AC17" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9BAD82CCEB142A93F5FC2EE352C5AC17" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9BAD82CCEB142A93F5FC2EE352C5AC17" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_075046F2D991D1ADD6572EE352C5FD11" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350" xlink:to="loc_us-gaap_SalesRevenueNetMember_075046F2D991D1ADD6572EE352C5FD11" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_AAF664AC0A4DDFA9637F2EE352C50A3E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_20CADF9A37AF42BC29C32EE352C59350" xlink:to="loc_us-gaap_AccountsReceivableMember_AAF664AC0A4DDFA9637F2EE352C50A3E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_BFC035F4E7A85F81FE4A2EE352C5936C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_BFC035F4E7A85F81FE4A2EE352C5936C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_BFC035F4E7A85F81FE4A2EE352C5936C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_BFC035F4E7A85F81FE4A2EE352C5936C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember_FEB4C68F277DAB38D6B12EE352C69296" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6" xlink:to="loc_us-gaap_ComputerEquipmentMember_FEB4C68F277DAB38D6B12EE352C69296" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_3DDA1417F7B9FA2604A32EE352C61EDA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4F166A77E46ED0F532812EE352C6F7F6" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_3DDA1417F7B9FA2604A32EE352C61EDA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_C63AB1FFDD296FC37B352EE352C63C78" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesTable_41E8A05C48DC16D9D2A92EE352C44AAE" xlink:to="loc_us-gaap_RangeAxis_C63AB1FFDD296FC37B352EE352C63C78" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_C63AB1FFDD296FC37B352EE352C63C78" xlink:to="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_C63AB1FFDD296FC37B352EE352C63C78" xlink:to="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_FA8D5B289DAED37B59E62EE352C6CF5A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C" xlink:to="loc_us-gaap_MinimumMember_FA8D5B289DAED37B59E62EE352C6CF5A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_0597E05182FCA08E6AC62EE352C6E773" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_6884C5F2FC6721348F772EE352C6E61C" xlink:to="loc_us-gaap_MaximumMember_0597E05182FCA08E6AC62EE352C6E773" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_SourcesOfPrimaryRevenue" xlink:label="loc_cvlt_SourcesOfPrimaryRevenue_1AF83DA766CA09705EBF2EE352C60F53" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_SourcesOfPrimaryRevenue_1AF83DA766CA09705EBF2EE352C60F53" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_CustomerSupportAgreement" xlink:label="loc_cvlt_CustomerSupportAgreement_E797160A6B8041E4941F2EE352C6A60D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_CustomerSupportAgreement_E797160A6B8041E4941F2EE352C6A60D" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_TimeframeOtherProfessionalServicesArePerformedAfterEnteringIntoAgreement" xlink:label="loc_cvlt_TimeframeOtherProfessionalServicesArePerformedAfterEnteringIntoAgreement_C599D431FFC9A62A37912EE352C6B552" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_TimeframeOtherProfessionalServicesArePerformedAfterEnteringIntoAgreement_C599D431FFC9A62A37912EE352C6B552" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_0E158A75B07C853E209A2EE352C6098B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_0E158A75B07C853E209A2EE352C6098B" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_DeferredTaxValuationAllowanceComprisedResearchTaxCredit" xlink:label="loc_cvlt_DeferredTaxValuationAllowanceComprisedResearchTaxCredit_73BE9F16934C3AD6B2472EE352C6592D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_DeferredTaxValuationAllowanceComprisedResearchTaxCredit_73BE9F16934C3AD6B2472EE352C6592D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_ED337B1C0FAF10C65DCE2EE352C69305" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_ED337B1C0FAF10C65DCE2EE352C69305" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_2A33AE003C7CEB859F382EE352C6CC6E" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_2A33AE003C7CEB859F382EE352C6CC6E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_33005BD4E1977EC5E9902EE352C6F68E" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_33005BD4E1977EC5E9902EE352C6F68E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_8270FD02D8B9114509752EE352C65054" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_8270FD02D8B9114509752EE352C65054" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetRetirementObligation" xlink:label="loc_us-gaap_AssetRetirementObligation_95745F142C481F6D9DEC2EE352C7A509" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_AssetRetirementObligation_95745F142C481F6D9DEC2EE352C7A509" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_1A2A34FEF8111771265B2EE352C7F0BA" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_AssetImpairmentCharges_1A2A34FEF8111771265B2EE352C7F0BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_AF85CE56B3A469AAD1FF2EE352C72674" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_AF85CE56B3A469AAD1FF2EE352C72674" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ReductionOfCommonStockAndAdditionalPaidInCapitalAsResultOfCommonStockRepurchases" xlink:label="loc_cvlt_ReductionOfCommonStockAndAdditionalPaidInCapitalAsResultOfCommonStockRepurchases_65B18AA6AE335E9034062EE352C7090C" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_ReductionOfCommonStockAndAdditionalPaidInCapitalAsResultOfCommonStockRepurchases_65B18AA6AE335E9034062EE352C7090C" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_IncreaseOfAccumulatedDeficitAsResultOfCommonStockRepurchases" xlink:label="loc_cvlt_IncreaseOfAccumulatedDeficitAsResultOfCommonStockRepurchases_81BCEFCC9B4CB08301942EE352C792CD" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_IncreaseOfAccumulatedDeficitAsResultOfCommonStockRepurchases_81BCEFCC9B4CB08301942EE352C792CD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdvertisingExpense" xlink:label="loc_us-gaap_AdvertisingExpense_67DEDAF6B3EBD05C78B32EE352C787E4" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_AdvertisingExpense_67DEDAF6B3EBD05C78B32EE352C787E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_0870DEF38A4334C1B88A2EE352C766E2" xlink:type="locator" />
    <definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_0870DEF38A4334C1B88A2EE352C766E2" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_MinimumTermPeriodForwardsContractsUtilizedForHedgingInMonths" xlink:label="loc_cvlt_MinimumTermPeriodForwardsContractsUtilizedForHedgingInMonths_9125541A3449479FC7532EE352C781A4" xlink:type="locator" />
    <definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_MinimumTermPeriodForwardsContractsUtilizedForHedgingInMonths_9125541A3449479FC7532EE352C781A4" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_MaximumTermPeriodForwardsContractsUtilizedForHedgingInMonths" xlink:label="loc_cvlt_MaximumTermPeriodForwardsContractsUtilizedForHedgingInMonths_F748A25F7A0FC6DBBE1E2EE352C731A3" xlink:type="locator" />
    <definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_cvlt_MaximumTermPeriodForwardsContractsUtilizedForHedgingInMonths_F748A25F7A0FC6DBBE1E2EE352C731A3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_09348A9F87D6E902D1972EE352C7D3C2" xlink:type="locator" />
    <definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cvlt_SummaryOfSignificantAccountingPoliciesLineItems_4247457D51D3A1403CB12EE352C6FD5A" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_09348A9F87D6E902D1972EE352C7D3C2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesComputationOfBasicAndDilutedNetIncomePerCommonShareDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesDeferredRevenueDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueArrangementLineItems" xlink:label="loc_us-gaap_DeferredRevenueArrangementLineItems_157025F555B0160BDE42217AEA041AB9" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueArrangementByTypeTable" xlink:label="loc_us-gaap_DeferredRevenueArrangementByTypeTable_9C9B264E9D63CC96F4C5217AEA042CB0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_157025F555B0160BDE42217AEA041AB9" xlink:to="loc_us-gaap_DeferredRevenueArrangementByTypeTable_9C9B264E9D63CC96F4C5217AEA042CB0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeAxis_CFD03BC2DC4945A63E84217AEA04E18C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DeferredRevenueArrangementByTypeTable_9C9B264E9D63CC96F4C5217AEA042CB0" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeAxis_CFD03BC2DC4945A63E84217AEA04E18C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeAxis_CFD03BC2DC4945A63E84217AEA04E18C" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:label="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeAxis_CFD03BC2DC4945A63E84217AEA04E18C" xlink:to="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SoftwareLicenseArrangementMember" xlink:label="loc_us-gaap_SoftwareLicenseArrangementMember_5834559B1012F5D10474217AEA04F930" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458" xlink:to="loc_us-gaap_SoftwareLicenseArrangementMember_5834559B1012F5D10474217AEA04F930" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_DeferredServicesRevenueMember" xlink:label="loc_cvlt_DeferredServicesRevenueMember_F7EF6D45585A734D5AA7217AEA04806D" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementTypeDomain_01EE5C02CCE82018A2B4217AEA041458" xlink:to="loc_cvlt_DeferredServicesRevenueMember_F7EF6D45585A734D5AA7217AEA04806D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent_4C248F4D25E21CBAAF74217AEA0413F2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_157025F555B0160BDE42217AEA041AB9" xlink:to="loc_us-gaap_DeferredRevenueCurrent_4C248F4D25E21CBAAF74217AEA0413F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueNoncurrent" xlink:label="loc_us-gaap_DeferredRevenueNoncurrent_C77D1CA907AA854506BB217AEA046F60" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_157025F555B0160BDE42217AEA041AB9" xlink:to="loc_us-gaap_DeferredRevenueNoncurrent_C77D1CA907AA854506BB217AEA046F60" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenue" xlink:label="loc_us-gaap_DeferredRevenue_E65593760B387004A4EB217AEA04C067" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueArrangementLineItems_157025F555B0160BDE42217AEA041AB9" xlink:to="loc_us-gaap_DeferredRevenue_E65593760B387004A4EB217AEA04C067" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesSummaryOfFairValueOfFinancialAssetsDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_48F8F4203BDAB0260BEF217AEA072D77" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DB1FB5EEBCFF9765E7D8217AEA060D2C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_48F8F4203BDAB0260BEF217AEA072D77" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DB1FB5EEBCFF9765E7D8217AEA060D2C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5C03B716D5D5D0BC9A04217AEA062BF3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_DB1FB5EEBCFF9765E7D8217AEA060D2C" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5C03B716D5D5D0BC9A04217AEA062BF3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5C03B716D5D5D0BC9A04217AEA062BF3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5C03B716D5D5D0BC9A04217AEA062BF3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_C88EDAD7E71FABE56796217AEA06B32C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_C88EDAD7E71FABE56796217AEA06B32C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_7322522263BA82023162217AEA07DFC2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_7322522263BA82023162217AEA07DFC2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5F639CF4A18209C423C1217AEA0711DB" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_88D4CB7678122C8CC2B7217AEA069A2F" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5F639CF4A18209C423C1217AEA0711DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_55963A19C3FA69B4EF9C217AEA0791E1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_48F8F4203BDAB0260BEF217AEA072D77" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_55963A19C3FA69B4EF9C217AEA0791E1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_HeldToMaturitySecuritiesFairValue" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_610712CE6ADCEB012672217AEA07F7E2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_48F8F4203BDAB0260BEF217AEA072D77" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_610712CE6ADCEB012672217AEA07F7E2" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesSummaryOfPotentialOutstandingCommonStockEquivalentsDetail" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.commvault.com/role/SummaryOfStockOptionsOutstandingUnderPlanAndLtipDetail" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_8275E0A9E213F644947AC400AC3F22DF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_8275E0A9E213F644947AC400AC3F22DF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_3C45716A3158D116232AC400AC3FFEE2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_8275E0A9E213F644947AC400AC3F22DF" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_3C45716A3158D116232AC400AC3FFEE2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_3C45716A3158D116232AC400AC3FFEE2" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_3C45716A3158D116232AC400AC3FFEE2" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeOneMember" xlink:label="loc_cvlt_ExercisePriceRangeOneMember_324C0058E3EF7041FC92C400AC3F437D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeOneMember_324C0058E3EF7041FC92C400AC3F437D" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeTwoMember" xlink:label="loc_cvlt_ExercisePriceRangeTwoMember_1E60F6F0B75DCD139D3DC400AC3F76C8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeTwoMember_1E60F6F0B75DCD139D3DC400AC3F76C8" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeThreeMember" xlink:label="loc_cvlt_ExercisePriceRangeThreeMember_E8E0DAC0A9BB718ABD9AC400AC40C131" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeThreeMember_E8E0DAC0A9BB718ABD9AC400AC40C131" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeFourMember" xlink:label="loc_cvlt_ExercisePriceRangeFourMember_6435C6EA05CD3B83407EC400AC40D594" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeFourMember_6435C6EA05CD3B83407EC400AC40D594" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeFiveMember" xlink:label="loc_cvlt_ExercisePriceRangeFiveMember_507D21FD5B0E95AB6076C400AC40B5C4" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeFiveMember_507D21FD5B0E95AB6076C400AC40B5C4" xlink:type="arc" />
    <loc xlink:href="cvlt-20150331.xsd#cvlt_ExercisePriceRangeSixMember" xlink:label="loc_cvlt_ExercisePriceRangeSixMember_2D52AB5ECC8C46F28CC5C400AC4010EF" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_E93160D11725FEFD67F3C400AC3F26AF" xlink:to="loc_cvlt_ExercisePriceRangeSixMember_2D52AB5ECC8C46F28CC5C400AC4010EF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_5375904B7C011CEBC0F7C400AC40331C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_5375904B7C011CEBC0F7C400AC40331C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_37AD0446F376F116AF82C400AC40B9A0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_37AD0446F376F116AF82C400AC40B9A0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_DEA0B34A21196F066A35C400AC4059F7" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_DEA0B34A21196F066A35C400AC4059F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_85A48CBB2A0A5AC8ABDDC400AC415A2D" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_85A48CBB2A0A5AC8ABDDC400AC415A2D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_6F9CDF9B016410E0477BC400AC41F7F2" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_6F9CDF9B016410E0477BC400AC41F7F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_D2D27A92E01EFEA8AB5FC400AC4128BA" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_D2D27A92E01EFEA8AB5FC400AC4128BA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_300A85FBAF7890319AA1C400AC41CC39" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_99A1591C40A4DE037371C400AC40AEF8" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_300A85FBAF7890319AA1C400AC41CC39" xlink:type="arc" />
  </definitionLink>
</linkbase>
