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Total Cost of Ownership Comparison of PCs With Hosted Virtual Desktops, 2011 Update

Gartner RAS Core Research Note G00209403, Federica Troni, Mark A. Margevicius, Michael A. Silver, 14 December 2010, RA12 08132011

Hosted virtual desktops (HVDs) bring the benefits of centralized architecture with improved operational efficiency. Total cost of ownership (TCO) savings exist, but these alone are not sufficient to justify a migration, as a high level of initial capital investments is required to build the back-end infrastructure.

Key Findings

• TheTCOofHVDscanrangefrom2%to13%lowerthancomparabledesktopdeployments.

• HVDimplementationscenariosthatusecurrentimagemanagementtechnologiesforlightdesktopapplicationloadshavelowerorsimilardirectcostsasthoseoftraditionaldesktopPCsdeployments.

• Newserverandimagemanagementtechnologiescanreducedirectcostsupto15%,andcanlowertheoverallTCOofHVDsby9to12%,ascomparedwitholder-generationHVDdeployments.

• Dedicatedandpooledimageimplementationswillincreasinglybereplacedbydynamicimageimplementations.

Recommendations

• UseHVDmigrationsasopportunitiestomovetohigherlevelsofmanagementandgainmoreflexibilityatlowerorsimilardirectcosts.

• EnsurethatallHVDbusinesscasesincludeTCOconsiderations,aswellasbenefitsthataremoredifficulttoquantify,suchastheabilitytogivesecureaccesstoapplicationsanddatatoremoteusers,theabilitytoaccommodateabroaderchoiceofclientdevices,andincreasedsecurityandmanageability.

• Selectdynamicimageimplementationsforlightloadsoverpooledimagedeployment,astheTCOfordynamicimagesisupto11%lower.

• Choosedynamicimagesaugmentedwithpersistentpersonalizationsoftwareinsteadofdedicatedimplementationwhenpersonalizationisrequired,astheTCOofdynamicimagesis9%to12%lowerthanthatofdedicatedimageimplementations.

2ANALYSISAnHVDisafull,thick-clientuserenvironment,whichisrunasavirtualmachine(VM)onaserverandaccessedremotely.HVDimplementationscompriseservervirtualizationsoftwaretohostdesktopsoftware(asaserverworkload),brokering/sessionmanagementsoftwaretoconnectuserstotheirdesktopenvironments,andtoolsformanagingtheprovisioningandmaintenance(e.g.,updatesandpatches)ofthevirtualdesktopsoftwarestack.Theadvantagesofthisclientarchitecturearethatitallowscentralizedmanagementofapplicationsanddata,highersecurityandspeedofprovisioning.Itisalsoaviableoptiontosecurelydeliverapplicationstoremoteusersandavarietyofclientdevices.TheTCObenefitsofHVDs,however,havebeenindoubtinthepast,asreductionsinITlaborandend-usercostswereoftenoffsetbythecapitalcostsrequiredtobuildtherequiredback-endinfrastructure.

SincethepublicationofourfirstresearchontheTCOoffirst-generationHVDsin2008,thetechnologyhasevolvedinmanyrespects.Inthisupdate,wewillaccountforseveraltechnologychangesthathaveresultedinnewimplementationscenariosanddifferentback-endinfrastructurerequirements.

Three Implementation ScenariosHVDscanbedeployedindifferentwaystoaccommodatetherequirementsofdifferentusersandorganizations.ThevariousimplementationoptionshavedifferentTCOimplications.SomeofthescenariosdescribedbelowemploythelatestgenerationofHVDsoftware;othersarelegacyscenariosthatarestilldeployedbysomeorganizations.Goingforward,thededicatedandpooledimagescenarioswillgraduallybereplacedbynewer,dynamicimage scenarios:

• Implementation of dynamically built images:Inthisscenario,onecopyoftheOSisstoredinthedatacenterandwillservemultipleuserimages.Imagesarecomposeddynamicallywhenuserslogon,bycombiningtheOSwiththeappropriatesetofapplications.ThisisachievedwithdifferenttechnologiesbydifferentHVDsoftwarevendors,butleadstosimilarresults.ThemainadvantageofthisimplementationscenarioovertheothertwoisthatitsubstantiallyreducesstoragerequirementsandsimplifiesmanagementoftheOS.Differentdegreesofpersonalizationofthedesktopareavailableforthesescenariostoday;however,foradvancedfeatures,third-partytoolsarerequired.Third-partytoolsmayberequiredtogobeyondbasicsettingsandfolder/fileredirection.

• Implementationofpooledimages:Inthisscenario,wesimulateadeploymentofgeneric,fullylocked-downimages,wherenodeduplicationtechnologyisused.Noimagededuplicationtechnologyisused.UserswillconnecttothefirstavailableVMastheylogon,andtheimageistakenbacktoitspristinestatewhentheuserhasfinishedusingit.Thisscenarioislesscomplex,fromamanagementperspective,thantheoneabove,butitissuitableonlyfornichegroupsofusers.

• Implementation of dedicated images:Inthisscenario,usersareassociatedwiththeirown,uniqueHVDimage.NoimagededuplicationtechnologyisusedandtheuserimageisexactlyasitwasonphysicalPC,butitisnowplacedinaVMandrunsonaserverinthedatacenter.EachimageincludesafullcopyoftheOS,applicationsanduser’spersonaldata.DedicatedimagesrepresentedoneofthefirstHVDdeploymentmethods.Theadvantageofthisoptionisthatitcanaccommodateusersthatrequirefullpersonalizationofthedesktop.Thedisadvantageisthatitistypicallyalsothemostexpensivescenario,asitrequiresalargeinfrastructurebuildout;and,unlikeotherscenarios,itdoesnothelporganizationsintroducehigherlevelsofmanageabilityfortheirclient-computingdeployments.

Heavy Versus Light LoadsWehavecalculatedtheTCOfortheseimplementationscenarioscomparingdifferentinfrastructuresetupsservingdifferentclient-computingworkloads.HeavyloadscenariosrepresentHVDdeploymentsfordemandingorsophisticatedusers,whichwillrequirehighnumbersofapplicationsandlargeamountsofdata.Lightloadscenarios,conversely,representimplementationsforusersrequiringfewerapplicationstodotheirjobandstorelimiteddata.Thedistinctionbetweenheavyandlightloadsimpactstheinfrastructurerequirements,asitaffectsmemoryandstoragerequirements,aswellastheuser-to-serverratio.

What’s NewSeveralitemshavechangedfromthe2008update:

• Hardware, software and facilities:Inthisupdate,wehaveincludedalowerthin-clientcost.Theper-servercostshavemorethandoubled,ascomparedwiththe2008numberssincewenowincludedual-CPU,quad-coreanddual-CPU,six-coreserverswith96GBand128GBofmemory,respectively.Thiscostispartlycompensatedforbythehigherdensityofusersperserverthatiscurrentlyachievable.Wehaveloweredtheper-usersoftwarecosts,whicharenowsetat$750,

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3includingannualmaintenance,butwehaveincludedahigher,more-realisticcostfortheHVDsoftware.Inthefirstscenario,wepresentcostsforaWindowsXPandaWindows7HVDdeployment;otherscenariosareWindows7-based.Wenowincludeelectricitycostsforthinclientsandservers.

• IT operations:Wehaveincreasedsalariesby6%.Formanagedscenarios,wenowincludethelaborcostsforthepersonnelrequiredtooperatemanagementtools.

• Administration:Underadministration,weaccountforstorageallocation,anelementthatwehaverevisedandincreasedsubstantially,perGartner’sclientfeedback.Wenowalsoaccountforstoragemanagement,acostitemthatwasnotincludedinourpreviousanalysis.

• End-user costs:Wehaveincreasedend-usersalariesby6%.

ManyofthechangeswehaveimplementedinthisupdatearethedirectconsequenceofthefeedbackofGarnerclientsengagedinpilotsandlivedeployments,andgointhedirectionofincreasingTCO.IndisputableTCObenefits,duetonewimagemanagementandservertechnologies,arepartlyoffsetbythechangeswehaveimplementedinthisupdate.

Assumptions Common to All ScenariosWebuildscenariosfora2,500-userdeployment,wheretheendpointdeviceisathinclientpricedat$350,withoutconsideringvolumediscounts(seeNote1).Thinclientshavealifecycleofsixyearsandfouryearsforservers.Forthepurposeofthisresearch,weassumeamixof50%dataentryusers(usingoneortwoapplicationstodotheirjob)and50%task-orientedworkers(usingasmallsetofapplicationsandoperatingwithinaknownsetoffunctions).Theusermiximpactsmostlyend-usercosts,as these are determined using the average salaries, but also the applicationmixandthehelpdeskfigures.Networkingcostsarenotincludedinourmodel,astheyvarytoowidelyfromorganizationtoorganization.Ourmodelorganizationhasonlyonelargecentrallocation,andtheHVDsareallhostedinonedatacenter.More-

dispersedorganizationsmayhavesignificantlydifferentcostsforimprovednetworkcommunications.Costsarepresentedperuser,peryear.

Eachuserhasacostallocationforsoftwarethatincludesanofficesuite,e-mailandcalendaring,andbusinessapplications.Ontopofthis,weallocate$180peruserfortheperpetuallicenseofHVDsoftware,plus$30peruser,peryearformaintenance.WeassumenoSoftwareAssurance,sowehaveincludedaMicrosoftVirtualDesktopAccess(VDA)licenseat$100peruser,peryear.

Whenappropriatethesecosts,wepresentTCOnumbersforthefollowingfourscenarios,whichassumedifferentlevelsofmanageability:

• Unmanaged:Userscaninstallapplicationsandchangesettings;littletonomanagementtoolsarebeingused.

• Moderately managed:Therearetoolsandgoodprocessesandpoliciesinplace;userscaninstallsoftwareandchangeatleast some settings.

• Locked and well-managed:Therearetools,processesandpoliciesinplace;userscannotinstallsoftwareorchangecriticalsettings.

Inmanagedscenarios,weincludethecostofserverstorunthemanagementtoolsandlaborcostsforthetechniciansrequiredtouse the tools.

Scenario 1: Dynamic Images, Light LoadsInthisscenario,wesimulatetheuseofcurrent-generationHVDsoftwarethatdynamicallyassemblestheimageforusers.InColumns2and3,weassumethat35-bladedual-CPUquad-coreXeonX5550serverswith96GBofmemorypricedat$13,350eachandtwochassisthatcanaccommodate16bladeseach,pricedat$2,700each,willbeusedtoaccommodateourmodeldeploymentof2,500users.Novolumediscountistakenintoconsideration.Weassumethevirtualizationofnineuserspercore,i.e.,upto80usersperserver.

IntheColumns4and5,weassumetheuseof24-blade,dual-CPUsix-coreXeonE7540serverswith128GBmemorypricedat$15,100eachandtwochassis.Again,weassumethevirtualizationofnineuserspercore;i.e.,upto108perserver.Weallocate1GBofstoragefordataperuserforWindowsXPscenarios,and1.5GBperuserinWindows7scenarios(forstoragecosts,seeNote2).Thisscenarioisadefactolocked-downscenario.Figure1illustratestheTCOforthisscenario,andcomparesittoatraditionallockedandwell-manageddesktopdeployment(forotherdesktopTCOscenarios,seeNote3).

Note 1. Thin-Client Versus Repurposed PCs for HVD Deployments

SeveralorganizationsuserepurposedPCsfortheirHVDdeployments;bydoing,sotheylowerinitialcapitalinvestments,However,theysufferhigherenergycostsandpotentiallyhigherIToperationscosts,asPCshaveafullOStomanageandsecure,andmorepartsthatcanpotentiallyfail.

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Inthisscenario,theTCOofHVDsis9%to10%lowerthanthoseofwell-managedandlocked-downPCs.Directcostsare4%to6%lowerthanthoseoftraditionaldesktops.SavingsareintheareaofIToperationsadministrationandend-usercosts.ComparedwiththepooledimagescenariodescribedinScenario3,adynamicimagescenariowithlightloadsis11%to12%lessexpensivetorunoverall,andhas13%to15%lowerdirectcosts.Capitalcostsare7%to9%lowerthanthoseofapooledimagescenario.

Figure 1. Dynamic HVD Deployment, Light Load

Source:Gartner(December2010)

Scenario 2: Dynamic Images, Heavy LoadsInthisscenario,weagainassumetheuseofcurrent-generationHVDsoftwarethatdynamicallyassemblestheimageforusers;thistime,however,wearehostingheavydesktopapplicationloads.InColumns2,4and6,weassumethat45-blade,dual-CPUquad-coreXeonX5550serverswith96GBmemorypricedat$13,350each,fittedinthreechassispricedat$2,700each,willbeusedtoaccommodatethe2,500users.Again,novolumediscountistakeninto consideration.

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InColumns3,4and7,weassumetheuseof30-blade,dual-CPUsix-coreXeonE7540serverswith128GBmemorypricedat$15,100eachandfourchassis.Again,weassumethevirtualizationofsevenuserspercore.Weallocate14.85GBofstoragefordata peruserforaWindows7scenario.

Inthisscenario,wesimulatesomedegreesofdesktoppersonalization,soweaddtosoftwarecostsanamountforpersistentpersonalizationsoftware($25foraperpetuallicense)andforanannualmaintenancefee($5).Figure2illustratestheTCOforthis scenario.

Figure 2. Dynamic HVD Deployment, Heavy Load

6Inthisscenario,theTCOofHVDsis15%to6%lowerthanthatofwell-managedandlocked-downPCs.Directcostsarelowerorcomparabletothoseofthetraditionaldesktopdeploymentinallscenarios.Itshouldbenoted,however,thataHVDscenariothatalsousespersistentpersonalizationsoftwareismoreflexiblethanawell-managedandlocked-downPC,asitallowsforsomedegreesofdesktopcustomization.

Forthisscenario,wehavepresentedaWindows7deployment.ForaWindowsXPdeployment,wewoulddefine13.2GBasthestorageallocationforeachuser.Thiswouldreflectinan11%lowerstoragecostanda0.4%decreaseindirect costs.

Scenario 3: Pooled Images, Light LoadsFigure3presentstheTCOforapooledimageimplementationforlightloads.Thistime,weassumethat35-blade,dual-CPUquad-coreXeonX5550serverswith96GBmemorypricedat$13,350each,fittedintwochassispricedat$2,700eachwillbeusedtoaccommodate2,500users.Again,novolumediscountistakenintoconsideration.Weassumethevirtualizationofnineuserspercore;i.e.,upto72usersperserver.AllocatedtoeachuserforaWindows7deploymentis15GBofstorage.

Inthisscenario,theTCOforHVDsiscomparabletothatofawell-managedandlocked-downdesktopscenario.ThedirectcostsandcapitalcostsforHVDsare,however,11%and16%higher,respectively.AnequivalentHVDdeploymentwithWindowsXPinsteadofWindows7wouldhave34%lowerstoragecostsand1%loweroveralldirectcosts.

Scenario 4: Dedicated Images, Heavy LoadsFigure4presentstheTCOforadedicatedimageimplementationforheavyloads.Specificassumptionsforthisscenarioinclude45-blade,dual-CPUquad-coreXeonX5550serverswith96GBmemorypricedat$13,350eachandthreechassisthatcanaccommodate16bladeseach,pricedat$2,700each.Weassumethevirtualizationofsevenuserspercore;i.e.,56usersperserver.Eachuserwillhave45GBofstorageforaWindows7deployment.

Comparedwithatraditionaldistributeddesktopscenario,theHVDimplementationwithdedicatedimagesforheavyloadsstillhasdirectcoststhatare8%to13%higher.TheoverallTCOofHVDsislowerinunmanagedandmoderatelymanagedscenarios,duetosignificantlylowerend-usercostsinallHVDscenarios.

AnequivalentHVDdeploymentwithWindowsXPinsteadofWindows7wouldhave11%lowerstoragecostsand1%loweroverall direct costs.


Figure 3. HVDs Pooled Images, Light Loads

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Figure 4. HVDs Dedicated Image Implementation, Heavy Loads

8Figure 5. Costs and Volume Discounts for Storage

Note 2. Storage Costs

Figure5summarizesthecostsandvolumediscountsforstorage.

Note 3. Desktop PC TCO

Figure6representsthedesktopTCOusedforcomparisonwiththeHVDTCOscenario.Thesedifferfromthefigurespublishedin“ResearchDesktopTotalCostofOwnership:2011Update”astheyarecalculatedusingthesameusermixastheoneusedintheHVDscenariosinthisresearch;i.e.,50%dataentryand50%task-orientedworkers.


Figure 6. Desktop PCs TCO
