Automatic deletion of Exchange backup copies

You can enable automatic deletion of LUN backup copies that store Exchange data. SnapManager checks for the level of overwrite utilization on the volume and triggers automatic deletion of backups if the level of overwrite utilization reaches the threshold.

Automatic deletion of LUN backup copies serves as the Exchange-aware replacement for or adjunct to the feature of Data ONTAP Snapshot copy deletion. SnapManager follows the following sequence of steps:

Deletes the oldest Snapshot copies.
Retains the specified number of total Snapshot copies on the volume.
Retains the most recent backup of any database (if it resides on the volume).
Retains any backup copies of databases no longer in existence.

You must select the backup retention level based on your backup copy creation and verification schedule. It is important that at least one verified backup copy remains on the volume if Snapshot copy deletion is triggered. Due to its Exchange-aware features, the automatic deletion of Snapshot copies does not necessarily prevent an out-of-space condition on the volume.

You must set the same number of backup sets to be deleted on database LUNs and transaction log LUNs. If there is a mismatch in this number, SnapManager attempts to delete backup sets based on the fractional reserve policy settings.

Example: automatic deletion of backup sets that span multiple volumes

If you have a backup copy that spans multiple volumes, with a different automatic deletion threshold configured on each volume, then for a specific volume, SnapManager deletes Snapshot copies based on the policy for that volume.

In this example, the automatic deletion settings for each volume are configured to take the following actions:

Volume 1: Delete all but 2 Snapshot copies if 20 percent overwrite reserve utilization is exceeded.
Volume 2: Delete all but 5 Snapshot copies if 20 percent overwrite reserve utilization is exceeded.
Volume 3: Delete all but 10 Snapshot copies if 20 percent overwrite reserve utilization is exceeded.

If the 20 percent overwrite reserve utilization threshold for Volume 1 is exceeded, SnapManager deletes all but two Snapshot copies, regardless of the policies for Volumes 2 and 3. If the 20 percent overwrite reserve utilization threshold for Volume 2 is exceeded, SnapManager deletes all but five Snapshot copies, regardless of the policies for Volumes 1 and 3.