Volume Shadow Copy Service

These options are effective only for Windows operating systems.

Using Volume Shadow Copy Service

This 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 Acronis Backup. Data consistency, in turn, ensures that the application will be recovered in the correct state and become operational immediately after recovery.

The preset is: Use Volume Shadow Copy Service.

Use VSS

When Use Volume Shadow Copy Service is selected, choose a snapshot provider from the following list:

• Hardware/software - Select automatically

  VSS will use the hardware-based provider that supports the source volume. If one is not found, VSS will try to use a software-based provider, the Microsoft Software Shadow Copy provider, and Acronis VSS Provider in turn.

• Software - Select automatically

  VSS will use any available software-based provider. If one is not found, VSS will try to use the Microsoft Software Shadow Copy provider, and Acronis VSS Provider in turn.

• Software - Acronis VSS Provider

  VSS will use Acronis VSS Provider.

• Software - System provider (selected by default)

  VSS will use the Microsoft Software Shadow Copy provider. We recommend choosing the system provider when backing up application servers (Microsoft Exchange Server, Microsoft SQL Server, Microsoft SharePoint, or Active Directory).

• Software - A software provider

  VSS will use any available software-based provider that supports the source volume.

• Hardware - Select automatically

  VSS will use the hardware-based provider that supports the source volume.

If a snapshot cannot be taken by using any of the specified providers, Acronis Backup will take a snapshot by using its own Snapshot Manager driver (snapman.sys).

Note: Using a hardware snapshot provider may require administrative privileges.

Do not use VSS

If you select Do not use VSS, Acronis Backup will take a snapshot by using its own Snapshot Manager driver.

Choose Do not use VSS 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 being 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.

About volume shadow copy writers

Before backing up the data of VSS-aware applications, make sure that the volume shadow copy writers for those applications are turned on by examining the list of writers that are present in the operating system. To view this list, run the following command:

vssadmin list writers

Note: In Microsoft Windows Small Business Server 2003, the writer for Microsoft Exchange Server 2003 is turned off by default. For instructions on how to turn it on, see the following Microsoft knowledge base article http://support.microsoft.com/kb/838183/.

Enabling VSS Full backup

The preset is: Disabled.

This option can be useful when you protect Microsoft Exchange Server with a disk-level backup.

If 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 backup.

Leave this option disabled in the following cases:

• If you use Acronis Backup 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 single-pass backup, enable the Log truncation setting in the Single-pass disk and application backup section of the Create backup plan or Back up now page.