Deleting backups automatically

Management of backups using automatic deletion

When you use the SnapManager Backup feature to start or schedule a backup, you can also specify the number of backups of that storage group and backup management group to be retained.

To do so, you use the Delete Oldest Backups In Excess Of field on the Backup and Verification tab or SnapManager Backup Wizard. When you select this option, SnapManager Backup automatically deletes the oldest backups of the same backup management group that exceed the number you specify, after the backup is complete.

Note
This is the recommended method for managing the number of snapshots you store on your system.

For more information about backup management groups, see How backup management groups are used.

What is deleted by automatic deletion

Automatic deletion deletes only backups with the following characteristics:

Its backup management group is the same as the type just created.
It has the prefix "exchsnap" (database backup) or "eloginfo" (transaction logs backup).
It is the oldest backup for this storage group of this type.
If it is not deleted, there would be more backups of this backup retention level than you specified in the Delete Oldest Backups In Excess Of field.

When additional backups could be preserved

SnapManager does not count backups that failed verification when counting the number of stored backups. Therefore, more backups might be preserved than you specify in the Delete Oldest Backups In Excess Of field. This result could occur in cases such as the following example.

Example

In this example, two storage groups with the following database backups compose the storage group set:

Storage Group A:
- exchsnap_orbit3_07-23-2003_16.21.07 (old backup, good)
- exchsnap_orbit3_recent (recent backup, good)
Storage Group B:
- exchsnap_orbit3_07-23-2003_16.21.07 (old backup, good)
- exchsnap_orbit3_recent (recent backup, inconsistent, bad)

The user set the Delete Oldest Backups in Excess Of field to 1 to preserve only one of each backup data set, the most recent one.

To preserve one good backup for Storage Group B, SnapManager's delete process does not delete the snapshot exchsnap_orbit3_07-23-2003_16.21.07. So two backups for Storage group A remain instead of one.