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Table Of Contents
VMware, Inc. 197
Chapter 9 Preserving the State of a Virtual Machine
Enabling and Disabling Background Snapshots for All Virtual
Machines
Takingasnapshotisnotinstantaneous.Youcaneditahostwidesettingtotake
snapshotsasabackgroundactivity.Thisallowsyoutocontinueworkingwhile
VMwareServerpreservesthestateofthevirtualmachine.However,enabling
backgroundsnapshotsforahostwithslowharddiskscanadverselyaffect
performance.
Ifyouexperiencesignificantperformanceproblemswhentakingor
restoringsnapshots,disablebackgroundsnapshots.
Theproceduretoconfigurethehostwidesettingtoenableanddisablebackground
snapshotsisdescribedin“EnablingandDisablingBackgroundSnapshots”on
page 115.
Snapshots and a Virtual Machine’s Hard Disks
Whenthevirtualmachinewritesnewdatatodiskafterasnapshotiscreated,thatdata
iswrittentoredologfiles.Thesefilescangrowquitelargeasnewlysaveddata
continuestoaccumulateinthem,untilyoutakeanactionthataffectsthesnapshot.Be
awareofhowmuch
diskspacethesefilesconsume.
RemoveasnapshotWhenyouremovethesnapshot,thechangesaccumulated
intheredologfilesarewrittenpermanentlytothebasevirtualdiskfiles.
ReverttoasnapshotWhenyoureverttothesnapshot,thecontentsoftheredo
logfilesarediscarded.
TakeasnapshotIfyoutakeasnapshotwhenthevirtualmachinealreadyhasa
snapshot,thechangesaccumulatedintheredologfilesarewrittenpermanentlyto
thebasevirtualdiskfiles.Anysubsequentchangesaccumulateinnewredologs.
Redologfilesandvirtualdiskfileshavea
.vmdkextensionandarestoredinthevirtual
machineʹsworkingdirectory.Formoreinformationaboutthefilesthatmakeupa
virtualmachine,includingsnapshotfiles,seeAppendix B,“FilesThatMakeUpa
VirtualMachine,”onpage 323.