I gave up on tape decades ago. Too many problems. It's slow AF compared to a live backup for restoring. That's if you CAN restore. Worst case scenario is you'll have to restore w/ a different tape drive -- and I've seen this fail right there. The original drive became out of alignment, but could still read/write it's own tapes. Nothing else would read them. I consider this tech useless now because of this.
I backup like this:
Linux server ---> rsync offsite
rsync offsite --- differential rsync of this live set
(ie: no direct access to differential backup set)
I do the same thing onsite, but will assume entire network is compromised and will rely on offsite for a good set of data