Regarding making the backups read-only after they are made, but still allowing new backups to be made: Why not use the snapshot facility of LVM? Once you are

Regarding making the backups read-only after they are made, but still allowing new backups to be made: Why not use the snapshot facility of LVM? Once you are done with a backup, create a snapshot and make it read-only. You can always mount the snapshot to see your data at that point in time and you dont need to worry about the data being erased in the live partition.