About backing up VSS-aware databases

Article:HOWTO13584  |  Created: 2008-01-05  |  Updated: 2013-10-17  |  Article URL http://www.symantec.com/docs/HOWTO13584
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About backing up VSS-aware databases

Backup Exec System Recovery Manager can co-exist with Microsoft VSS (Volume Shadow Copy Service) to automate the process of backing up VSS-aware databases like production Exchange 2003 and SQL 2005 databases, transaction logs on Windows Server 2003, Active Directory, and the latest versions of Oracle. VSS-aware databases are auto-enabled and cannot be turned off.

Licensing Backup Exec System Recovery on client computers does not give users any rights to use VSS. VSS must be licensed separately from Microsoft, and users must conform to any license agreement or documentation that accompanies VSS.

About backing up non-VSS-aware databases

VSS lets IT administrators create a shadow copy backup of drives on a server. The shadow copy includes all files (including open files).

When a backup job starts, Backup Exec System Recovery alerts the VSS that a recovery point is about to be created. VSS then communicates this information to the VSS-aware databases and puts them into a quiesced (sleep) state. (Backup Exec System Recovery always attempts to communicate with VSS if it is installed on a desktop or server and tries to provide VSS with information to quiesce databases.)

While in this quiesced state, the databases continue to write to transaction logs, and Backup Exec System Recovery takes an instantaneous snapshot that also includes any open files. When the snapshot is complete, VSS is notified, the databases are activated, and the transaction logs continue writing to the database. (To verify that there are no errors and that VSS is running, you should check the Microsoft error logs.)

While the recovery point is being created from the snapshot, the databases and applications return to an active state and continue to write data.

This kind of integration means that you can back up business-critical databases at anytime during the day without affecting productivity.

Additional points for backing up and restoring VSS-aware databases include the following:

  • Backup Exec System Recovery supports VSS Exchange Server 2003, which implements VSS technology. If the database load is heavy, the VSS request might be ignored.

  • Run backups during the lightest load time.

  • Additional backup applications are not needed to run Backup Exec System Recovery with Exchange databases.

  • There are known VSS issues that are resolved in 2003 Service Pack 1, and also the Exchange 2003 Service Pack 1.

  • Backup Exec System Recovery prevents VSS snapshots from occurring during the time the Backup Exec System Recovery is creating a recovery point.

  • If a full system restore is done from a recovery point, individual files can be restored from a VSS snapshot. However, the recommended restore process is to use Backup Exec System Recovery to mount the recovery point file as a virtual drive (using the Recovery Point Browser). Or, if you enabled file indexing when you defined the backup job, you can use Backup Exec Retrieve to quickly restore the files you need.

  • After a full system restore from a Backup Exec System Recovery recovery point, a VSS snapshot that was taken prior to the date and time of the Backup Exec System Recovery snapshot can no longer be used to restore the entire system.

Database corruption may occur if the computer is low on hard disk space when you are rebuilding a database at the same time you are running a backup. To avoid database corruption, you should quiesce the database before backing it up, and you should not rebuild or restore the database at the same time that you are backing it up. Finally, to avoid possible conflict, Backup Exec System Recovery does not let you take VSS snapshots and Backup Exec System Recovery snapshots at the same time.

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