With this parameter, the software will clear space for the backup being created by deleting old backups. If the parameter is not specified and the destination is out of space, the backup will fail.
The archive will be cleaned up only during backup and only if there is not enough space to complete the operation. The software will act as follows:
Delete the oldest full backup with all dependent incremental/differential backups
If there is only one full backup left and a full backup is in progress, then delete the last full backup with all dependent incremental/differential backups
If there is only one full backup left, and an incremental or differential backup is in progress, an error occurs saying there is a lack of available space