Volume Shadow Copy Service (VSS) for virtual machines

This option defines whether quiesced snapshots of virtual machines are taken. To take a quiesced snapshot, the backup software applies VSS inside a virtual machine by using VMware Tools or Hyper-V Integration Services.

The preset is: Enabled.

If this option is enabled, transactions of all VSS-aware applications running in a virtual machine are completed before taking snapshot. If a quiesced snapshot fails after the number of re-attempts specified in the "Error handling" option, and application backup is disabled, a non-quiesced snapshot is taken. If application backup is enabled, the backup fails.

If this option is disabled, a non-quiesced snapshot is taken. The virtual machine will be backed up in a crash-consistent state. We recommend that you keep this option enabled at all times, even for virtual machines that do not run VSS-aware applications. Otherwise, even file-system consistency cannot be guaranteed inside the captured backup.