NetVault Plug-in for SQL Server 12.0

NetVault Plug-in for SQL Server 12.0 - User Guide

Volume Shadow Copy Service (VSS)

Microsoft supports the ability to create snapshots of SQL Server data using VSS. VSS allows volume backups to be performed while applications on the system continue to write to the volumes. Microsoft provides a SQL Server VSS Writer that permits backup programs such as Plug‑in for SQL Server to copy SQL Server data while SQL Server is running. VSS-based backups do not negatively affect SQL Server’s performance or stability.

In VSS backup method, Plug‑in for SQL Server creates 2*N (where, N represents the number of databases) number of user connections with SQL Server. Maximum N user connections are active at a time.


	IMPORTANT: A disadvantage of VSS backups is that the SQL Server VSS Writer does not support the ability to restore a database to an alternate SQL Server Instance. This disadvantage applies whether that instance is on the same server and host or an alternate server and host.

Using VSS, you can:

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Use snapshots to perform consistent backups to disk- or tape-based storage devices.

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Create and store snapshots as backups on NetVault Backup-supported disk arrays.


	NOTE: The Backup Files to Storage option is supported with any disk-based storage. To use the Retain Snapshot as Persistent and Discard After options, the data that you back up must reside on a NetVault Backup-supported disk array. Also, for persistent snapshots, only the metadata is copied to the target.

Reviewing SQL Server recovery models

When a database is created, a recovery model is enabled. Microsoft defines a recovery model as a “database property that controls the basic behavior of backup and recovery of the database.” The database’s recovery model controls how its transactions are logged, whether the transaction log can be backed up, and which kinds of restores are supported. SQL Server provides three different recovery models: Simple, Full, and Bulk-Logged.

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Simple Recovery Model: With a Simple Recovery Model, log backups are not supported. Therefore, changes since the most recent backup are not protected. In the unfortunate event of failure, these changes must be re-run. PIT recovery is not allowed.

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Full Recovery Model: Full Recovery Model databases require log backups; therefore, no work is lost due to a lost or damaged data file. PIT recovery is supported, assuming backups are complete up to the point-of-failure.

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Bulk-Logged Recovery Model: Bulk-Logged Recovery Model databases require log backups. The Bulk-Logged Recovery Model is a variation of the Full Recovery Model that permits high-performance bulk-copy operations. This model reduces log space usage by bulk-logging most bulk operations. If a log is damaged or bulk-operations have occurred since the most recent Transaction Log backup, these changes must be re-run. PIT recovery is not supported for bulk-logged databases.

Choosing the best recovery model

Consider the following when choosing a recovery model for a database:

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Simple Recovery Model: The Simple Recovery Model should only be enabled for databases that are not updated frequently such as test, development, or databases mostly containing read-only data.

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Full Recovery Model: The Full Recovery Model should be enabled for transactional databases where full recoverability and preventing work loss in a full range of recovery scenarios is required.

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Bulk-Logged Recovery Model: The Bulk-Logged Recovery Model should be used temporarily when bulk operations, such as bulk inserts or index creation, are performed on Full Recovery Model databases. The Bulk-Logged Recovery Model increases performance and reduces log space consumption during these operations; you can switch databases back to full recovery immediately after the bulk operations have completed.

For more information, see Recovery Models and Transaction Log Management in the SQL Server Books Online.