Volume Shadow Copy Service (VSS)

This option is effective only for Windows operating systems.

The option defines whether a Volume Shadow Copy Service (VSS) provider has to notify VSS-aware applications that the backup is about to start. This ensures the consistent state of all data used by the applications; in particular, completion of all database transactions at the moment of taking the data snapshot by the backup software. Data consistency, in turn, ensures that the application will be recovered in the correct state and become operational immediately after recovery.

The snapshot is used only during the backup operation, and is automatically deleted when the backup operation completes. No temporary files are kept.

The preset is: Enabled. Automatically select snapshot provider.

You can select one of the following:

  • Automatically select snapshot provider

    Automatically select among the hardware snapshot provider, software snapshot providers, and Microsoft Software Shadow Copy provider.

  • Use Microsoft Software Shadow Copy provider

    We recommend choosing this option when backing up application servers (Microsoft Exchange Server, Microsoft SQL Server, Microsoft SharePoint, or Active Directory).

Disable this option if your database is incompatible with VSS. Snapshots are taken faster, but data consistency of the applications whose transactions are not completed at the time of taking a snapshot cannot be guaranteed. You may use Pre/Post data capture commands to ensure that the data is backed up in a consistent state. For instance, specify pre-data capture commands that will suspend the database and flush all caches to ensure that all transactions are completed; and specify post-data capture commands that will resume the database operations after the snapshot is taken.

If this option is enabled, files and folders that are specified in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BackupRestore\FilesNotToSnapshot registry key are not backed up. In particular, offline Outlook Data Files (.ost) are not backed up because they are specified in the OutlookOST value of this key.

Enable VSS full backup

If this option is enabled, logs of Microsoft Exchange Server and of other VSS-aware applications (except for Microsoft SQL Server) will be truncated after each successful full, incremental or differential disk-level backup.

The preset is: Disabled.

Leave this option disabled in the following cases:

  • If you use Agent for Exchange or third-party software for backing up the Exchange Server data. This is because the log truncation will interfere with the consecutive transaction log backups.
  • If you use third-party software for backing up the SQL Server data. The reason for this is that the third-party software will take the resulting disk-level backup for its "own" full backup. As a result, the next differential backup of the SQL Server data will fail. The backups will continue failing until the third-party software creates the next "own" full backup.
  • If other VSS-aware applications are running on the machine and you need to keep their logs for any reason.

Enabling this option does not result in the truncation of Microsoft SQL Server logs. To truncate the SQL Server log after a backup, enable the Log truncation backup option.