Specifications

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VMware GSX Server Virtual Machine Guide
if you want the virtual machine to be powered on or powered off when you launch it,
be sure it is powered on or powered off when you take the snapshot.
Snapshots and a Virtual Machine’s Hard Disks
When a snapshot exists and the virtual machine saves data to disk, that data is written
to a set of redo-log files. These files have .REDO as part of the filename and are stored
in the virtual machine’s working directory.
Redo-log files can grow quite large as 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 logs consume.
• Remove the snapshot — When you remove the snapshot, the changes
accumulated in the redo-log files are written permanently to the base disks
(either the virtual disk files or the physical disks, depending on your virtual
machine’s hard disk configuration). This is similar to committing changes to a
disk in GSX Server 2.
• Revert to the snapshot — When you revert to the snapshot, the contents of the
redo-log files are discarded. Any additional changes are, once again,
accumulated in the redo-log files. This is similar to discarding changes to a disk in
GSX Server 2.
• Take a snapshot — If you take a snapshot when the virtual machine already has
a snapshot, changes stored in the redo-log files are written permanently to the
base disk. Then any subsequent changes are, once again, accumulated in the
redo-log files. Depending upon how large the redo-log 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 going on 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.