Specifications

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Chapter 16 Using Snapshots
Snapshots and Other Activity in the Virtual Machine
Whenyoutakeasnapshot,beawareofotheractivitygoingoninthevirtualmachine
andthelikelyeffectofrevertingtothatsnapshot.Ingeneral,itisbesttotakeasnapshot
whennoapplicationsinthevirtualmachinearecommunicatingwithothercomputers.
Thepotentialforproblemsis
greatestifthevirtualmachineiscommunicatingwith
anothercomputer,especiallyinaproductionenvironment.
Forexample,ifyoutakeasnapshotwhilethevirtualmachineisdownloadingafile
fromaserveronthenetwork,thevirtualmachinecontinuesdownloadingthefile,
communicatingitsprogresstotheserver.Ifyou
reverttothesnapshot,communications
betweenthevirtualmachineandtheserverareconfusedandthefiletransferfails.
Anotherexampleistakingasnapshotwhileanapplicationinthevirtualmachineis
sendingatransactiontoadatabaseonaseparatemachine.Ifyoureverttothat
snapshot—especiallyif
yourevertafterthetransactionstartsbutbeforeithasbeen
committed—thedatabaseislikelytobeconfused.
Taking a Snapshot
Takingasnapshotisasynchronousoperation.Alluseroperationstothevirtual
machineduringthisperiodareblockedforsnapshotanddataconsistency.Thetime
takentodevelopasnapshotdependsontheamountofdataandtheloadontheserver.
Onaverage,thetimerangesfrom30to
40secondsforminimalsnapshotcreation.
Youcantakeasnapshotwhileavirtualmachineispoweredon,poweredoff,or
suspended.Ifyouaresuspendingavirtualmachine,waituntilthesuspendoperation
hasfinishedbeforetakingasnapshot.
Youmustpoweroffthevirtualmachinebeforetakingasnapshot
ifthevirtualmachine
hasmultipledisksindifferentdiskmodes.Forexample,ifyouhaveaspecialpurpose
configurationthatrequiresyoutouseanindependentdisk,youmustpoweroffthe
virtualmachinebeforetakingasnapshot.
To take a snapshot
1 ChooseInventory>VirtualMachine>Snapshot>TakeSnapshot.
Youcan
alsoclicktheTakeasnapshotofthisvirtualmachinebutton,orright‐click
thevirtualmachineandchooseSnapshot>TakeSnapshot.
TheTakeVirtualMachineSnapshotwindowappears.
2Typeanameforyoursnapshot.