When a snapshot is created manually, regardless of the resource type, the user can specify No Automatic Deletion or the Retain Until value. The Retain Until value is the integrated retention value for when the snapshot should be automatically deleted by the system. This option does not restrict the user from manually deleting a snapshot at any point-in-time. When No Automatic Deletion is selected, the snapshot is not deleted by the system under any circumstances until the user deletes the snapshot manually. For any snapshots with the Secure Snapshot setting enabled, users cannot set the No Automatic Deletion option. Snapshots are not automatically deleted as the usable capacity becomes depleted on a PowerStore system.
The Retain Until value can be set by the user during manual snapshot creation. The Retain Until value is automatically set when a snapshot is created by a snapshot rule. At any time, the user can update the Retain Until value or edit the snapshot and set it to No Automatic Deletion. When updating the Retain Until value, the user can either shorten or extend the life of the snapshot by setting the value to a chosen date and time.
For snapshots with the Secure Snapshot setting enabled, a user can extend the Retain Until value, but cannot decrease it. When the Retain Until value is reached, the system automatically deletes the snapshot. If a snapshot with the Secure Snapshot setting enabled needs to be deleted before this time, contact your support provider.
The PowerStore system uses a snapshot-aging service which runs every minute in the background. This service is controlled by the system and cannot be modified. When the service runs, it identifies snapshots across the cluster with a Retain Until value which has occurred in the past and marks the snapshot for deletion. Snapshots are then deleted in batches across the appliances to stagger the deletion process. This method not only guards against the chance of impacting host I/O when hundreds to potentially thousands of snapshots must be deleted, but also increases the efficiency of the deletion process.