3.1

View Manager Administration Guide
118 VMware, Inc.
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disk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baselinestatebycarrying
outadesktoprefresh.
Thin Provisioning
Operatingsystemdatadisksanduserdatadisksuseaprocesscalledthinprovisioning
inordertominimizestoragecosts.Disksthatemploythisprocessoccupynomore
spacethanthatrequiredbythedataitcontains,andthisreducestheamountofphysical
diskcapacityinitiallyrequiredwhenadesktop
iscreated.
Storage Overcommit
Whenthedatastoreforanewlinkedclonedesktoppoolisbeingassigned,
administratorscancontrolhowaggressivelythesystemassignsnewvirtualmachines
tothefreespaceavailableonthedatastorebymodifyingthestorageovercommit
property.
Whenthestorageovercommitlevelislow,themajorityoffreespaceis
usedasbuffer
inwhichthedeltadisksforeachclonecanexpand.Astheovercommitlevelincreases,
lessspaceisreservedforindividualdeltadiskgrowthbutmorevirtualmachineswill
fitonthedatastore.
Averyaggressivelevelofstorageovercommitresultsinarelativelysmallamountof
space
beingreservedfordeltadiskexpansion;however,administratorscanaddalotof
extravirtualmachinestothedatastoreiftheypredictthatthedeltadisksofeachvirtual
machinewillnevergrowtotheirmaximumpossiblesize.
Whileahighovercommitlevelmaybeoptimalforcreatingalargenumber
ofvirtual
machines,adesktoppoolofthistypealsodemandsmoreattentionfromthe
administratorinordertoensurethattheremainingdiskspaceisnotcompletely
consumedbyvirtualmachineexpansion.Thisconditioncanbepreventedby
periodicallyrefreshingorrebalancingthedesktoppoolandreducingthesize
ofthe
operatingsystemdatatoitsbaselinelevel.
N
OTEThinlyprovisioneddisksdonotreduceinsizeifdataisremoved.