Understanding Snapshot Retention Policies

You can configure a snapshot retention policy for all NEXT3-snapshot-enabled volumes. A retention policy specifies the following:

• The number daily snapshots to retain

  For example, if daily snapshots are set to 10, then the last 10 daily snapshots will be retained. If daily snapshots are set to 0, then the current daily snapshot will be deleted when the next day starts.

• The number of weekly snapshots to retain

  A weekly snapshot is the latest snapshot taken during the week.

  	Tip
  	A week is defined as starting on Monday and ending on Sunday.

  Example 1:

  Let's say snapshots were successfully taken every day until the current day, which is Sunday. The weekly snapshot is the one taken on Sunday, as it is the latest snapshot taken this week.

  Example 2:

  Snapshots were successfully taken every day until the current day, except the Saturday and Sunday snapshots, which were not taken because the appliance was turned off. The weekly snapshot is the one taken on Friday, as it is the latest snapshot taken this week.

• The number of monthly snapshots to retain

  A monthly snapshot is the latest snapshot taken during the month.

  Example 1:

  Let's say snapshots were successfully taken every day until the current date, which is April 30th. The monthly snapshot is the one taken on the 30th, as it is the latest snapshot taken this month.

  Example 2:

  Snapshots were successfully taken every day until the current date, except snapshots for the 25th through the 30th, which were not taken because the appliance was turned off. The monthly snapshot is the one taken on 24th, as it is the latest snapshot taken this month.

• The number of yearly snapshots to retain

  A yearly snapshot is the latest snapshot taken during the year.

  Example 1:

  Let's say snapshots were successfully taken every day until the current date, which is the December 31st. The yearly snapshot is the one taken on the 31st, as it is the latest snapshot taken this year.

  Example 2:

  Snapshots were successfully taken every day until the current date, except snapshots for the 25nd through the 31st were not taken because the appliance was turned off. The yearly snapshot is the one taken on 24th, as it is the latest snapshot taken this year.

• The minimum amount of time that snapshots should be retained

  You can protect recent snapshots from deletion, by specifying the minimum number of hours that snapshots of any type should be retained. After this amount of time has elapsed, the snapshots will be deleted according to the retention policy.

  The default value is 24 hours, meaning that snapshots created less than 24 hours ago will not be deleted.

Predefined Snapshot Retention Policies

The appliance offers the following pre-defined retention policies:

If desired, you can configure a custom retention policy.