Using snapshot technology with the SQL Agent

  • Modified Date:
  • Article ID:000076186

Description

Backup Exec uses snapshot technology by default for SQL Server backups. The SQL Agent supports full snapshot backups using Microsoft's Volume Shadow Copy Service (VSS), a snapshot provider service only available on Windows 2003 or later. The use of snapshot technology can reduce both restore time and backup performance on the server.

When you submit a backup job that uses snapshot technology, a snapshot of each volume is created, providing a point-in-time record of the data. Backup Exec uses snapshot technology to momentarily suspend write activity to a volume so that a snapshot of the volume can be created. The data is then backed up from the snapshots, and then the snapshots are deleted.

Note:

Use snapshot technology with jobs that use deduplication devices.

Before you use snapshot technology with the SQL Agent, review the following information:

  • With snapshot technology, a point-in-time view of the SQL database is "snapped" and then backed up, leaving the actual SQL database open and available for users.

  • SQL backups that use snapshot technology are considerably larger than regular SQL backups (also known as streaming backups).

  • Performing consistency checks before backup is strongly recommended.

    See Configuring Backup Exec to run a consistency check before every SQL backup

  • The SQL Agent supports only full snapshot backups; transaction log snapshots and differential snapshots are not supported.

  • With the SQL Agent, snapshot and streaming backups are interoperable when you restore SQL data.

  • Performing database consistency checks both before and after backups affects the time required for the backup jobs.

The following SQL backup options are not supported with snapshot backups:

  • Use checksums on backup (SQL 2005 or later)

    This option is used as a redundancy check, and works with the Run verify only and do not restore data restore option.

  • SQL Server 2008 Enterprise Edition software compression

  • Create on-disk copies of SQL backups to be placed on the SQL Server where the database is located

Note:

Microsoft Virtual Shadow Copy Service (VSS) snapshots are not the same as SQL database snapshots. VSS snapshots enable you to create point-in-time snapshots of disk volumes and shares; database snapshots enable you to create point-in-time copies of SQL databases.

 

See Using database snapshots for SQL Server.

Terms of use for this information are found in Legal Notices.

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