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NetVault Plug-in for SQL Server 12.2 - User Guide

Introducing NetVault Backup Plug-in for SQL Server Planning your SQL Server deployment Installing and removing the plug-in Configuring the plug-in Backing up data
Defining a backup strategy Understanding snapshot-based backups Reviewing the compression features Performing Online VDI backups Performing VSS backups in SQL Server Example of creating a full VDI backup of an AlwaysOn Availability Group on Windows
Restoring data Using the CLI with the plug-in Troubleshooting

Defining a VSS backup strategy and reviewing types

Plug‑in for SQL Server provides the following types of VSS backups:

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Full Database backup: Full Database backups are supported by:
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SQL Server versions: Windows - 2008 and later
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Recovery models: All
A VSS Full Database backup backs up database data and all the log files necessary to bring the database up to a transactionally consistent state at restore time. Full Database backups consume more space and time per backup and are typically supplemented by differential backups, which are created more frequently. With Full Database backups, you can re-create an entire database in one step by restoring the database.
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Differential Database backup: Differential Database backups are supported by:
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SQL Server versions: Windows - 2008 and later
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Recovery model: All
A VSS Differential Database backup backs up only the data that has changed since the most recent base Full Database backup. A Differential Database backup contains only those parts of the database files that have changed. Differential Database backups are smaller and faster to create than the Full Database backups. A Differential Database backup is useful if some of the database’s tables are modified more frequently than others. In this case, Differential Database backups allow you to back up frequently without the overhead of Full Database backups.
 
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IMPORTANT: If a failover occurs in an Active/Passive Failover Cluster and your VSS-based backup strategy includes Differential Database backups, perform a Full Database backup of the modified configuration as soon as possible. When the plug-in detects that a failover occurred and a different node holds the active role, the plug-in automatically runs a full backup for the next scheduled backup. However, if you must perform a restore to the new active node before a new full backup is run, database changes that occurred between the last full backup and the new full backup might be lost.
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Copy-Only backup: Copy-Only backups are supported by:
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SQL Server versions: Windows - 2008 and later
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Recovery models: All
VSS Copy-Only backups are independent of the normal sequence of backups. Unlike a full backup, a Copy-Only backup cannot serve as the base backup for a series of differential backups. Also, performing a Copy-Only backup does not affect what is backed up by the next differential backup. Copy-Only backups are ideal for situations that require special purposes, such as creating test databases.

Examples of VSS backup sequences

Following are few examples of backup sequences that support multiple restore scenarios and that you can implement to meet your SQL Server data protection requirements.

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Full Database backups only: When requirements guarantee data protection up to the previous day, performing Full Database backups nightly should be sufficient when one or more of the following conditions exist:
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Backup windows are large.
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Databases are small.
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Updates are infrequent across entire database.
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Databases are only for testing or development purposes.
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Entire database is read-only.
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Full Database and Differential Database backups: When requirements guarantee data protection up to the previous day and backups must be completed quickly, Full Database backups coupled with Differential Database backups is a valid strategy. For example, Full Database backups are performed every Sunday night at 11:00 P.M., while Differential Database backups are performed Monday through Saturday at 11:00 P.M. Each Differential Database backup includes all the changes since the last Full Database Backup, which is known as the differential base.
No matter when recovery is performed, the same number of restore jobs is required. For example, if recovery is performed on Tuesday, Sunday’s Full Database backup and Monday’s Differential Database backup must be restored. Whereas, if recovery is performed on Thursday, Sunday’s Full Database backup followed by Wednesday’s Differential Database backup must be restored.
Even though Differential Database backups increase not only in size but in duration, restores are quicker due to the fewer number of restore jobs that must be run.
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Copy-Only backups: When requirements demand that a backup be created without interfering with regular scheduled backup sequences, Copy-Only backups is a valid strategy. Often times, you must create a full backup outside of the regular backup schedule, such as when refreshing your test databases. This process could potentially interfere with the regular backup schedule and throw off subsequent differential backups. The Copy-Only backup allows administrators to run non-regular Full Database backups at any time without interfering with scheduled backups.

Understanding snapshot-based backups

If you are using SQL Server 2010 or later, the plug-in can use a hardware or software VSS provider to create persistent or non-persistent VSS-based snapshots. The plug-in uses a VSS provider to create snapshots on the client, and then copies the selected data from the snapshot, or snapshots, to a storage device.

To create and use persistent snapshots, the data that you want to back up must reside on NetVault Backup-supported disk arrays. If you attempt to create persistent snapshots with data residing on an unsupported disk array, or with data residing in local drives (for which snapshots are taken using the Microsoft Software VSS Provider), taking the required hardware snapshots fails, and the plug-in defaults to using software snapshots. When taking software snapshots the data is only backed up to storage (even if the option Backup Files to Storage is not selected), and non-persistent snapshots are created.

The same issue occurs if your backup includes data that resides in different storage that mixes NetVault Backup-supported disk arrays and unsupported disk arrays or local drives.

For more information about NetVault Backup-supported OS versions and disk arrays, see the Quest NetVault Backup Compatibility Guide.

Backing up system databases

The SQL Server system databases are essential for the operation of a server instance. These backups enable recovery of the SQL Server if a system failure occurs, such as loss of a hard disk.

The system databases that you must always back up include msdb, master, and model. The master and msdb databases have a Simple Recovery Model while the model database has a Full Recovery Model. For replicated databases, you should also back up the distribution database.

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master: The master database records system-level information for a SQL Server system. For the master database, SQL Server supports only Full Database backups. Quest recommends that you schedule routine Full Database backups of master.
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msdb and model: SQL Server uses the msdb database to store data. SQL Server uses the model database as a template when you create a user database. Back up the model and msdb databases whenever they are updated. You can back up the model and msdb databases in the same way that you back up user databases. Quest recommends that you create only Full Database backups of the model database. Because it is small and rarely changes, backing up the log is not required.
 
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NOTE: The plug-in cannot back up tempdb or Resourcedb databases.

For more information, see Backing Up and Restoring System Databases in SQL Server Books Online.

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