Data Protection for SQL Server with IBM SAN Volume Controller and IBM Storwize V7000

The way in which you configure the VSS provider for IBM SAN Volume Controller and IBM Storwize® V7000 controls the type of FlashCopy® operation that runs when you create a VSS snapshot.

The VSS provider that you use with IBM SAN Volume Controller and IBM Storwize V7000 must have the following characteristics:

• If the VSS provider is configured to use incremental FlashCopy, you can take only one backup version. Each VSS snapshot request for a source volume causes an incremental refresh of the same target volume.

  When you delete the VSS snapshot, it is removed from the VSS inventory. If you create another VSS snapshot of the same source volume, the process results in an incremental refresh of the target volume.

The following guidelines apply when you use Data Protection for SQL Server with SAN Volume Controller- based storage:

• Do not use a combination of space-efficient and fully allocated target volumes. Choose to use either space-efficient or fully allocated volumes for FlashCopy targets. Provision enough target volumes in the SAN Volume Controller VSS_FREE volume group for the backup versions you require. If you use fully allocated target volumes, the capacity size of those volumes must match the size of the source volumes.
• If space-efficient virtual disks (VDisks) are used for backup targets, set the IBM® VSS provider background copy value to zero by entering the ibmvcfg set backgroundCopy 0 command. To activate the changes, restart the IBM VSS system service after you enter the command.

  You can transition your data from fully allocated targets to space-efficient targets by using fully allocated targets as if those targets are space-efficient when the background copy rate is set to 0.

• To determine how much storage space is required for each local backup, the backup LUNs require the same amount of storage space as the original LUNs. For example, if you have a 100 GB database on a 200 GB LUN, you need a 200 GB LUN for each backup version.
• Do not use a combination of persistent and nonpersistent VSS snapshots.
• Do not mix COPY and NOCOPY FlashCopy relationships from the same source volume or volumes.
• Enable the autoexpand option for the space-efficient target volumes to avoid out-of-space conditions.
• Allocate enough space for space-efficient target volumes to hold 120 % of the data that is expected to change on the source volume in the time between snapshots. For example, if a database changes at a rate of 20 % per day, VSS backups complete every six hours, and a steady rate of change throughout the day is assumed. The expected change rate between snapshots is 5 % of the source volume (20/4). Therefore, the allocated space for the space-efficient target volumes is to be 1.2 times 5 % equal to 6 % of the source volume size. If the rate of change is not consistent throughout the day, allocate enough space to the target volumes to accommodate the highest expected change rate for the period between snapshots.

  You can use VSS instant restore operations with

• Do not delete snapshots manually. Allow Data Protection for SQL Server to delete backup versions that are based on the defined policy to ensure that deletion occurs in the correct order.