Specifications

Table Of Contents
VMware, Inc. 129
Chapter 6 View Composer
ViewManageradministratorscansimultaneouslyupdate(orchange)theoperating
systemsofalllinkedclonedesktops,installorupdateclientapplications,ormodifythe
desktophardwaresettingsbycarryingouttheseactivitiesontheParentVMandthen
anchoringthelinkedclonestoanewsnapshotofthisconfiguration.Thisaction
iscalled
desktoprecomposition.
Administratorscanalsoreturntheoperatingsystemdataofeachlinkedclone
desktop—whichmayhaveexpandedthroughongoingusage—toitsoriginalstate
(that oftheParentVM)bycarryingoutanactioncalleddesktoprefresh.
InFigure 61thedesktopuserdataisconfiguredtoresideona
separatedisk,soit
remainsunaffectedbydesktoprecompositionordesktoprefreshactions.Inthisway,
systemmodificationisdecoupledfromuserdatastorage.
ViewAdministratordeliversahighleveloverviewofwhatactionsarebeingcarried
out.Policiescancontrolwhatactionsareexecutedandatwhattimeinorder
to
minimizedisruptiontotheuserbase.Connecteduserscanbenotifiedwithcustom
messagesifanupdatethatwillaffecttheirsessionisabouttotakeplace.
Linked Clone Desktop Disk Usage
Theinitialdiskusageofalinkedclonevirtualmachineisfarlowerthanthatofafull
clonebecausetheoperatingsystemandclientapplicationsarederivedfroma
Parent VM.Thegreatlyreducedstorageoverheadforoperatingsystemanduserdata
isaccomplishedthroughtheuseofdeltadisksand
thinprovisioning.
Everynewdesktopcreatedinastandard(nonlinkedclone)automatedpoolisa
duplicateofabasetemplate.Consequently,eachstandardcloneusesthesameamount
ofdiskspaceasthebasetemplatebecausetheoperatingsystemdataanduserdataof
thebasetemplateisreplicatedby
everyclonecreatedinthepool.
ViewComposergreatlyreducesthephysicalstorageoverheadoflinkedclonedesktop
poolsthroughuseofdeltadisks:abstractstoragemechanismswhoselogicalsizecanbe
greaterthantheirphysicalsize.Thindiskgrowthdependsonfactorsincluding
workload,poweroffpolicy,andpooltype.
Inalinkedclonedeployment,deltadisksareusedbythedesktoptostorethedata
differencebetweenitsownoperatingsystemandtheoperatingsystemofthe
Parent VMfromwhichitisderived.Immediatelyafterdeployment,thedifference
betweentheParentVMandeachofitslinkedclonesisextremely
small;therefore,the
deltadiskisalsoextremelysmall.
NOTELinkedclonescanalsobeanchoredtoanewsnapshotofacompletelydifferent
ParentVM.