3.0.1

Table Of Contents
View Manager Administration Guide
96 VMware, Inc.
Thinprovisioneddisks(thindisks)areusedbythelinkedclonestostoreuserdata,and
arenotlinkedtotheParentVM.Thistypeofdiskoccupiesnomorespacethanthat
requiredbythedataitcontainsbutdoesnotreduceinsizeifdataisremoved.These
disksarenotaffectedbyrecompositionorrefreshev
ents.
Storage Overcommit
Whenthedatastoreforanewlinkedclonedesktoppoolisbeingassigned,
administratorscancontrolhowaggressivelythesystemassignsnewvirtualmachines
tothefreespaceavailableonthedatastorebymodifyingthestorageovercommit
property.
Whenthestorageovercommitlevelislow, themajorityoffreespaceisusedasbuffe
r
inwhichthedeltadisksforeachclonecanexpand.Astheovercommitlevelincreases,
lessspaceisreservedforindividualdeltadiskgrowthbutmorevirtualmachineswill
fitonthedatastore.
Averyaggressiv elev elofstorageovercommitresultsinarelativelysmallamountof
spacebeingre
servedfordeltadiskexpansion;however,administratorscanaddalotof
extravirtualmachinestothedatastoreiftheypredictthat thedeltadisksofeachvirtual
machinewillnevergrowtotheirmaximumpossiblesize.
Whileahighovercommitlevelmaybeoptimalforcreatingalargenumberofvi
rtual
machines,adesktoppoolofthistypealsodemandsmoreattentionfromthe
administratorinordertoensurethattheremainingdiskspaceisnotcompletely
consumedbyvirtualmachineexpansion.Thisconditioncanbepreventedby
periodicallyrefreshingorrebalancingthedesktoppoolandreducingthesizeofthe
ope
ratingsystemdatatoitsbaselinelevel.
Storageovercommitlevelscanbevariedbetweendifferenttypesofdatatstoresinorder
toaddressthedifferentlevelsofthroughputoneachdatastore(forexample,NAS
versusSAN).Wherethroughputisrelativelyslow,theovercommitlevelcanbesettoa
lowerleveltoensurethatasmallernu
mberofclonesarecreatedonthedatastore.
Conversely,ahigherlevelofovercommitcouldbeappliedtodatastoresthatexhibita
greaterrateofdatatransfer.
Storageovercommitonlyappliestodeltadisks.Itdoesnotapplytouserdisksor
standard(nonlinked)cloneswhereth
indisksareused.
Desktop Recomposition
InFigure 62anassigneddesktopcloneislinkedtoreplica1,whichitselfisacopyof
ParentVM1.Arecompositionactionisinitiatedwhentheadministratorselectsa
differentsnapshotinthesameParentVMordifferentParentVM(asinthisexample).
Ineithercaseanewre
plicaisprovisioned.