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, Hyper-V Integration Services, or Virtuozzo Guest Tools.
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.