Specifications

Table Of Contents
VMware, Inc. 115
Chapter 5 Preserving the State of a Virtual Machine
newly!saved!data!continues!to!accumulate!in!them!until!you!take!an!action!that!affects!
the!snapshot.!Be!aware!of!how!much!disk!space!these!files!consume.
! Remove!the!snapshot!!When!you!remove!the!snapshot,!the!changes!accumulated!
in!the!new!virtual!disk!file!is!written!permanently!to!the!base!disks!(either!the!
virtual!disk!files!or!the!physical!disks,!depending!on!your!virtual!machine’s!hard!
disk!configuration).!
! Revert!to!the!snapshot!!When!you!revert!to!the!snapshot,!the!contents!of!the!
newly!created!virtual!disk!file!is!discarded.!Any!additional!changes!are,!once!
again,!accumulated!in!a!new!virtual!disk!file.!
! Take!a!snapshot!!If!you!take!a!snapshot!when!the!virtual!machine!already!has!a!
snapshot,!changes!stored!in!the!new!virtual!disk!file!are!written!permanently!to!the!
base!disk.!Any!subsequent!changes!again!accumulate!in!a!new!virtual!disk!file.!
Depending!on!how!large!the!virtual!disk!file
!is,!taking!a!new!snapshot!can!take!
some!time
Snapshots and Other Activity in the Virtual Machine
When!you!take!a!snapshot,!be!aware!of!other!activity!occurring!in!the!virtual!machine!
and!the!likely!impact!of!reverting!to!the!snapshot.!In!general,!it!is!best!to!take!the!
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.
Consider!a!case!in!which!you!take!a!snapshot!while!the!virtual!machine!is!downloading!
a!file!from!a!server!on!the!network.!After!you!take!the!snapshot,!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.
Or!consider!a!case!in!which!you!take!a!snapshot!while!an!application!in!the!virtual!
machine!is!sending!a!transaction!to!a!database!on!a
!separate!machine.!If!you!revert!to!
the!snapshot!!especially!if!you!revert!after!the!transaction!starts!but!before!it!has!been!
committed!!the!database!is!likely!to!be!confused.
Settings for Snapshots
You!can!specify!what!VMware!Server!does!with!the!snapshot!whether!the!machine!is!
powered!on!or!powered!off.!