Ways to manage the backup and deletion of transaction logs

SnapManager provides advanced options that allow you to manage the transaction logs associated with the backup management group.

For any backup job, you can choose to skip the backup of transaction logs that Exchange will truncate after the SnapManager Backup operation finishes.
See Option to back up transaction logs that Exchange will truncate.
When you delete backup Snapshot copies (whether automatically or explicitly), you can choose to skip the deletion of Snapshot copies of LUNs that contain transaction logs related to the selected backup management group, if deleting those logs would that break the continuity of transaction logs between the previous backup and the present time.
See Option to retain up-to-the-minute restore ability.
When you explicitly delete backup sets (or related SnapInfo Snapshot copies) that contain selected storage groups, you can expand the scope of the deletion to include backups that contain only some of the selected storage groups (in addition to backups that contain all of the selected storage groups).
See Explicitly deleting backups and SnapInfo Snapshot copies.

Option to back up transaction logs that Exchange will truncate

By default, SnapManager Backup jobs back up selected database files and all associated transaction logs. This part of the backup process also entails creating a database Snapshot copy, truncating transaction logs (by removing any entries already committed to the database), and creating a SnapInfo Snapshot copy.

If you do not need to retain up-to-the-minute restore ability from a backup that is not the most recent, you can reduce the amount of disk space that is consumed by transaction log backups by choosing to skip the backup of transaction logs that Exchange will truncate after the SnapManager Backup operation finishes.

This feature is managed using the "Back up transaction logs that will be truncated by Exchange at the end of the backup" option in the Advanced Options dialog box.

The option to back up all transaction logs (including those that Exchange will truncate after the backup operation finishes) is selected by default.
When this option is deselected (so that you do not back up transaction logs that Exchange will truncate after the SnapManager Backup operation finishes), database and transaction log verification cannot be deferred.

This option is automatically selected the next time SnapManager is started.

Option to retain up-to-the-minute restore ability

If you delete backups that are not the oldest backups in your backup list, and the corresponding transaction logs are also deleted, this makes the older remaining backups no longer available for an up-to-the-minute restore. The reason is that the transaction logs are no longer contiguous from the time when the older backup was taken to the present time. This can happen when you are deleting backups of a particular backup management group.

When you automatically or explicitly delete backups for a backup management group (whether based on Snapshot copy age or quantity), you also have the option to ensure that this is done without creating a break in the continuity of transaction logs between the previous backup and the present time. Limiting the backup deletion in this way allows you retain the ability to use the older backups in an up-to-the-minute restore.

To enable this safeguard, use the "Retain up-to-the-minute restore ability for older backups in other backup management groups" option in the Advanced Options dialog box, at the cost of using more space on your storage system for the logs that are not deleted. This option is selected by default.
If you know you will not need to perform an up-to-the-minute restore from the older backups, then you should allow the logs to be deleted in order to free up more space on the storage system holding the backups. This option is automatically selected the next time SnapManager is started.

Example

As an example, suppose that you have the following backups stored:

Now, you perform a Standard backup, and specify that only the four most recent Standard backups be retained. After this backup is complete, the oldest Standard backup is deleted, and the daily backup becomes point-in-time only:

To avoid this situation, you can enable the "Retain up-to-the-minute restore ability for older backups in other backup management groups" option.

About using only one backup management group

If all backups have the same backup management group designation, deselecting this option has no effect. That is, the SnapInfo directories (transaction logs) will be deleted according to the "Delete backups" setting, and the "Retain up-to-the-minute restore ability" option is effectively ignored.

For more information about using backup management groups, see Using backup management groups in backup and verification.