Dell PowerFlex 4.5.x Technical Overview

Snapshot policies

Snapshot policies enable you to define policies where you can configure the number of snapshots to take at a given time for one or more volumes.

Snapshots are taken according to the rule defined. You can define the time interval in-between two rounds of snapshots as well as the number of snapshots to retain, in a multi-level structure. For example, take snapshots every x minutes/hours/days/weeks. There are one to six levels, with the first level having the most frequent snapshots.

Example:

Rule: Take snapshots every 60 minutes

Retention Levels:

• 24 snapshots
• 7 snapshots
• 4 snapshots

After defining the parameters, select the source volume to add to the snapshot policy. You can add multiple source volumes to a snapshot policy, but only a single policy per source volume is allowed. Only one volume per vTree may be used as a source volume of a policy (any policy). When you remove the source volume from the policy, you must choose how to handle snapshots. Snapshots created by the policy are referred to as auto snapshots. In PowerFlex Manager, this is indicated if a snapshot policy is displayed for the snapshot.

• If the source volume has no auto snapshots, you cannot unassign the source volume from the snapshot policy. You can remove auto snapshots from Snapshots in PowerFlex Manager.
• If the source volume has auto snapshots but none of them are locked, you are prompted to confirm that you would like to delete all auto snapshots. If any of the auto snapshots are locked, the locked auto snapshots are just detached from the snapshot policy, but not deleted. You need to manually remove auto snapshots. It does not matter if the auto snapshot is locked or not, you can still delete.