A retention policy defines how long must backups and snapshots be retained by Veeam Backup for Microsoft Azure.
Veeam Backup for Microsoft Azure supports the following retention types:
Snapshot-based retention removes all restore points (snapshots) in the backup chain that exceed the specified retention threshold.
The following is an example of a backup chain consisting of 7 restore points (snapshots) in total. The oldest restore point that was created on Monday is being removed because, as per example, the retention threshold is set to 6 and has been exceeded by one after the 7th restore point (represented as the green block on the right) has been created.
To remove obsolete snapshots, Veeam Backup for Microsoft Azure calculates outdated restore points and deletes them from the Azure resource group during each backup policy session.
A repository-based retention removes all restore points (backups) in the backup chain that are older than the specified retention period.
The following is an example in which you have set to keep restore points only for a year (365 days), and a new restore point is being taken on a day 366 (represented as the green block on the right). In such a scenario, the first restore point that was taken on January 1, 2019 (represented as the gray block on the left) is going to be removed.
Veeam Backup for Microsoft Azure uses an obsolete snapshots retention to remove snapshots that exceed the specified period. For more information, see Configuring Retention Settings.