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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2020-08-05T09:54:50.6137737+00:00 -->
<!-- Version            : 5.0.1.476 -->
<!-- Package ID         : e3e2742be9e24d429083981f15d1ed22 -->
<!-- Copyright (c) 2020 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="psnl_RecognitionPeriodOfIncrementalCosts" name="RecognitionPeriodOfIncrementalCosts" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_AllOtherCustomersMember" name="AllOtherCustomersMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_InventoryAndOtherDeferredCostsAbstract" name="InventoryAndOtherDeferredCostsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_AssetsAmortizedCostBasis" name="AssetsAmortizedCostBasis" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="psnl_AssetsGrossUnrealizedGains" name="AssetsGrossUnrealizedGains" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_AssetsGrossUnrealizedLosses" name="AssetsGrossUnrealizedLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="psnl_LongTermMarketableDebtSecuritiesMaturityPeriod" name="LongTermMarketableDebtSecuritiesMaturityPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_LongTermInvestmentsMember" name="LongTermInvestmentsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ChangeInFairValue" name="ChangeInFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_ReclassificationOfWarrantLiabilityToAdditionalPaidInCapitalOnConversion" name="ReclassificationOfWarrantLiabilityToAdditionalPaidInCapitalOnConversion" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_WarrantLiabilityMember" name="WarrantLiabilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_DebtDisclosureLineItems" name="DebtDisclosureLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_DebtDisclosureTable" name="DebtDisclosureTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_TriplePointCapitalLimitedLiabilityCompanyMember" name="TriplePointCapitalLimitedLiabilityCompanyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_SeriesCRedeemableConvertiblePreferredStockMember" name="SeriesCRedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_LineOfCreditFacilityMaturityDate" name="LineOfCreditFacilityMaturityDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_LineOfCreditFacilityExtendedMaturityDate" name="LineOfCreditFacilityExtendedMaturityDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_ClassOfWarrantOrRightTerm" name="ClassOfWarrantOrRightTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_EstimatedFairValueOfWarrants" name="EstimatedFairValueOfWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_PercentageOfPrepaymentFee" name="PercentageOfPrepaymentFee" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_PercentageOfPrinciplePaymentAmount" name="PercentageOfPrinciplePaymentAmount" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_CoLocatedDataCenterSpaceMember" name="CoLocatedDataCenterSpaceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_SeriesARedeemableConvertiblePreferredStockMember" name="SeriesARedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_SeriesBRedeemableConvertiblePreferredStockMember" name="SeriesBRedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_NumberOfFractionalSharesIssued" name="NumberOfFractionalSharesIssued" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_NumberOfIssuedCommonSharesReducedUponConversion" name="NumberOfIssuedCommonSharesReducedUponConversion" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_TwoThousandElevenEquityIncentivePlanMember" name="TwoThousandElevenEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_TwoThousandNineteenEmployeeStockPurchasePlanMember" name="TwoThousandNineteenEmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_OptionsGrantedAsMeritAwardsMember" name="OptionsGrantedAsMeritAwardsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ShareBasedCompensationByShareBasedPaymentAwardPercentageOfExercisePriceOfOptionsGranted" name="ShareBasedCompensationByShareBasedPaymentAwardPercentageOfExercisePriceOfOptionsGranted" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsAndOtherThanOptionsGrantsInPeriodButNotVested" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsAndOtherThanOptionsGrantsInPeriodButNotVested" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodButNotVested" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodButNotVested" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAndEquityInstrumentsOtherThanOptionsGrantsInPeriodUnvestedAndUnexercisedButReservedSharesYetGranted" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAndEquityInstrumentsOtherThanOptionsGrantsInPeriodUnvestedAndUnexercisedButReservedSharesYetGranted" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_TwoThousandNineteenPlanMember" name="TwoThousandNineteenPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_TwoThousandTwentyInducementPlanMember" name="TwoThousandTwentyInducementPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesIncreaseInAvailableForGrant" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesIncreaseInAvailableForGrant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_TwoThousandElevenAndTwoThousandNineteenEquityIncentivePlanAndTwoThousandTwentyInducementPlanMember" name="TwoThousandElevenAndTwoThousandNineteenEquityIncentivePlanAndTwoThousandTwentyInducementPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ClosingPriceOfCommonStock" name="ClosingPriceOfCommonStock" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentEqualToOrGreaterThanAverageMarketCapital" name="ShareBasedCompensationArrangementByShareBasedPaymentEqualToOrGreaterThanAverageMarketCapital" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_ShareBasedCompensationArrangementByShareBasedPaymentAverageMarketCapitalizationThresholdSatisfactionPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAverageMarketCapitalizationThresholdSatisfactionPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_TwoThousandNineteenEquityIncentivePlanAndTwoThousandTwentyInducementPlanMember" name="TwoThousandNineteenEquityIncentivePlanAndTwoThousandTwentyInducementPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ConvertiblePreferredStockWarrantsLineItems" name="ConvertiblePreferredStockWarrantsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_ConvertiblePreferredStockWarrantsTable" name="ConvertiblePreferredStockWarrantsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_TermLoanMember" name="TermLoanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_AlternativeInvestmentTerm" name="AlternativeInvestmentTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_EstimatedFairValueConvertiblePreferredStockWarrant" name="EstimatedFairValueConvertiblePreferredStockWarrant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_FairValuesOfConvertiblePreferredStockWarrants" name="FairValuesOfConvertiblePreferredStockWarrants" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_ReclassificationOfOutstandingPreferredStockWarrantLiabilityToAdditionalPaidInCapitalFairValue" name="ReclassificationOfOutstandingPreferredStockWarrantLiabilityToAdditionalPaidInCapitalFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="psnl_WarrantExercised" name="WarrantExercised" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_CommonStockIssuedForExerciseOfWarrant" name="CommonStockIssuedForExerciseOfWarrant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="psnl_CommonStockWarrantsLineItems" name="CommonStockWarrantsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_CommonStockWarrantsTable" name="CommonStockWarrantsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_OptionsToPurchaseCommonStockMember" name="OptionsToPurchaseCommonStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_UnvestedRestrictedStockUnitsMember" name="UnvestedRestrictedStockUnitsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="psnl_UnvestedEarlyExercisedCommonStockOptionsMember" name="UnvestedEarlyExercisedCommonStockOptionsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
