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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
le from a server on the network, the virtual machine continues downloading the le and communicating its
progress to the server. If you revert to the snapshot, communications between the virtual machine and the
server are confused and the le transfer fails. Depending on the task that you are performing, you can create
a memory snapshot or you can quiesce the le system in the virtual machine.
Memory Snapshots
The default selection for taking snapshots. When you capture the virtual
machine's memory state, the snapshot retains the live state of the virtual
machine. Memory snapshots create a snapshot at a precise time, for example,
to upgrade software that is still working. If you take a memory snapshot and
the upgrade does not complete as expected, or the software does not meet
your expectations, you can revert the virtual machine to its previous state.
When you capture the memory state, the virtual machine's les do not
require quiescing. If you do not capture the memory state, the snapshot does
not save the live state of the virtual machine and the disks are crash
consistent unless you quiesce them.
Quiesced Snapshots
When you quiesce a virtual machine, VMware Tools quiesces the le system
of the virtual machine. A quiesce operation ensures that a snapshot disk
represents a consistent state of the guest le systems. Quiesced snapshots are
appropriate for automated or periodic backups. For example, if you are
unaware of the virtual machine's activity, but want several recent backups to
revert to, you can quiesce the les.
If the virtual machine is powered o or VMware Tools is not available, the
Quiesce parameter is not available. You cannot quiesce virtual machines that
have large capacity disks.
I Do not use snapshots as your only backup solution or as a long-term backup solution.
Take a Snapshot in the VMware Host Client
Snapshots capture the entire state of the virtual machine at the time you take the snapshot. You can take a
snapshot when a virtual machine is powered on, powered o, or suspended. To take a snapshot of a
suspended virtual machine, wait until the suspend operation nishes before you take a snapshot.
When you create a memory snapshot, the snapshot captures the state of the virtual machine's memory and
the virtual machine power seings. When you capture the virtual machine's memory state, snapshots that
capture the memory state of a virtual machine take longer to complete. You might also see a momentary
lapse in response over the network.
When you quiesce a virtual machine, VMware Tools quiesces the le system in the virtual machine. The
quiesce operation pauses or alters the state of running processes on the virtual machine, especially processes
that might modify information stores on the disk during a restore operation.
Application-consistent quiescing is not supported for virtual machines with IDE or SATA disks.
N Do not use VMware snapshots to backup dynamic disks on Windows. If you take a snapshot of a
dynamic disks on Windows you cannot revert to the snapshot. Snapshot technology does not have visibility
in dynamic disks and cannot preserve the quiesced state of the disk les.
Prerequisites
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If you are taking a memory snapshot of a virtual machine that has multiple disks in dierent disk
modes, verify that the virtual machine is powered o. For example, if you have a special purpose
conguration that requires you to use an independent disk, you must power o the virtual machine
before taking a snapshot.
vSphere Single Host Management - VMware Host Client
76 VMware, Inc.