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Chapter 6 View Composer
Administratorscanalsoreturntheoperatingsystemdataofeachlinkedclone
desktop—whichmayhaveexpandedthroughongoingusage—toitsoriginalstate
(that of theParentVM)bycarryingoutanactioncalleddesktoprefresh.
ViewAdministratordeliversahigh‐leveloverviewofwhatactionsarebeingcarried
out.Policiescancontrolwhatactio
nsareexecutedandatwhattimeinorderto
minimizedisruptiontotheuserbase.Connecteduserscanbenotifiedwithcustom
messagesifanupdatethatwillaffecttheirsessionisabouttotakeplace.
Linked Clone Desktop Disk Usage
Theinitialdiskusageofalinkedclonevirtualmachineisfarlow erthanthatofafull
clonebecausetheoperatingsystemandclientapplicationsarederivedfromaParent
VM.Thegreatlyreducedstorageoverheadforoperatingsystemanduserdatais
accomplishedthroughtheuseofdeltadisksandthinprovision
ing.
Everynewdesktopcreatedinastandard(non‐linkedclone)automatedpoolisa
duplicateofabasetemplate.Consequently,eachstandardcloneusesthesameamount
ofdiskspaceasthebasetemplatebecausetheoperatingsystemdataanduserdataof
thebasetemplateisreplicatedbyev
eryclonecreatedinthepool.
ViewComposergreatlyreducesthephysicalstorageoverheadoflinkedclonedesktop
poolsthroughuseofdeltadisks:abstractstoragemechanismswhoselogicalsizecanbe
greaterthantheirphysicalsize.Thindiskgrowthdependsonfactorssuchasworkload,
power‐offpolicy,pooltypeandsoforth.
Inali
nkedclonedeployment,deltadisksareusedbythedesktoptostorethedata
differencebetweenitsownoperatingsystemandtheoperatingsystemoftheParent
VMfromwhichitisderived.Immediatelyafterdeployment,thedifferencebetweenthe
ParentVMandeachofit
slinkedclonesisextremelysmall;thus,thedeltadiskisalso
extremelysmall.
Becausethedeltadisksforeachdesktopwillinevitablygrowovertime,duringlinked
clonedeploymentyoucandefinethemaximumallowablesizeofeachvirtualmachine,
uptotheoriginalsizeoftheParentVM.Theamountofdi
skspacerequiredtostorethe
differencebetweenthelinkedcloneoperatingsystemdataandParentVMoperating
systemdatawilltypicallyremainfarsmallerthanthatrequiredbyastandardclone.If
thesizeofthedeltadiskgetstoolargeitcanbereturnedtoitsba
selinestatebycarrying
outadesktoprefresh.
N
OTELinkedclonescanalsobeanchoredtoanewsnapshotofacompletelydifferent
ParentVM.