When you run a one-time archive job or create a schedule, you can set a retention period for the archive set. Archive sets cannot be deleted with the purge and overwrite options until they have exceeded their retention periods. (For details, see Purge and Overwrite.) However, if you prepare media that contains existing archive sets, they are deleted regardless of retention settings. For details about preparing media, see Preparing archive media.
Retention settings for archive sets are impacted by backup groups (see Backup groups). Backup groups can be archived across multiple sets, and because backups must be restored as a group, the archived backup with the latest retention date determines the retention date for all sets containing backups belonging to the group. For example, if a set containing a full backup has a later retention date than the sets containing the differentials in the group, the retention setting for the set containing the full backup is applied to the sets containing the differentials. For more details, see Impact of a backup group on archive retention settings.
You can view retention settings using the procedure described in To view archive information. The figure below illustrates how retention settings display in the Administrator Interface of the Unitrends appliance.