Automatic aggregate Snapshot copy deletion

As more and more data blocks in the aggregate are changed, the aggregate Snapshot reserve gradually becomes full. Because aggregate Snapshot copies usually do not need to be preserved for long periods of time (you usually need only the most recent aggregate Snapshot copy), Data ONTAP automatically deletes the oldest aggregate Snapshot copies to recover space in the aggregate Snapshot reserve.

When an aggregate Snapshot copy is automatically deleted, a message similar to this one is logged: Sun May 23 15:10:16 EST [wafl.snap.autoDelete:info]: Deleting snapshot ‘nightly.0’ in aggregate ‘aggr1’ to recover storage

In most cases you should leave automatic aggregate Snapshot copy deletion enabled. If this option is turned off for a particular aggregate, then every volume in that aggregate requires up to two times its size in order to satisfy a space guarantee of volume.

However, in some specific situations, you may need to disable automatic aggregate Snapshot copy deletion temporarily. For example, if one plex of a RAID SyncMirror aggregate has to be offline for some time, you would want to make sure that the SyncMirror-based Snapshot copy is not automatically deleted.

To disable automatic aggregate Snapshot copy deletion, you use the aggr options command. For example, to turn off automatic aggregate Snapshot copy deletion for the aggregate myAggr, you would use the following command: aggr options myAggr snapshot_autodelete off

Note: If you do not have sufficient free space in your aggregate to satisfy the new space requirements when you turn off automatic aggregate Snapshot copy deletion, then space guarantees will be disabled for one or more of your volumes. For this reason, you should plan to reenable automatic aggregate Snapshot copy deletion as quickly as possible.

Parent topic: Aggregate Snapshot copy management