When registering a new Backup Job you can specify retention rules that are applied to all recovery points (learn more here) related to it.
Each Retention Rule takes into account two different concepts: schedule and retention.
Schedule refers to a plan that specifies the instants in which a specific Backup Job should be triggered.
Retention refers to the operation of filtering out, from a list of recovery points, only recovery points contained in a specific time window.
Each retention rule applies to a specific time granularity. Supported time granularities are “hours”, “days”, “weeks” and “months”.
Retention Rules can be created both during Backup Job registration and update.
The maximum number of Retention Rules admitted for each Backup Job is 5.
Suppose you want to create a Backup Job with the following rules:
Every day at 00:00, keep 7 recovery points
Every Monday at 06:00, keep 4 recovery points
The granularity of the first rule is a day. Keeping 7 recovery points means filtering out from a time window of 7 days the recovery points created with the first rule. The same applies to the second rule.
Suppose on October 1st, 2018, you’ve activated the Backup Job with the just defined Retention Rules; on October 29th, at 00:00 am, Noovolari Smart Backup would be managing the following recovery points.
Next recovery points will be taken on October 29th, at 06:00 am, for the Weekly Retention Rule and on October 30th, at 00:00 am, for the Daily Retention Rule.
Thus, on October 30th, at 00:00 am, after the daily recovery point was taken, the scenario would change as described below.
As you can see, as time windows shift, recovery points that are no more included in them will be deleted.
Consistency involves the integrity of the data and should be considered within individual programs, databases, and application systems.
This concept is strongly tied with data usability to enable correct recovery of potential failures.