These steps will be performed when cleaning up a source
First, all Backup models that do not have a directory on the filesystem will be deleted.
Next old backups will be deleted. You can read more on we determine that a backup is "old" in this section.
All backups that are mark as failed (their backup process didn't complete fully) and are older than a day will be deleted.
Real backup size will be calculated. Because of the use of hard links in the backup process, the size of a backup will not match the size it actually takes on disk. Here, we are going to calculate what the real disk space usage is for each backup and save it in the real_size_in_kb on each Backup.
When you no longer need to support a source and want to remove all backups, the cleanup command will take care of it.
You can remove the source record in the backup_server_sources table and execute the cleanup job.