I know I am coming into this a little late. but here is my 2 cents.
when a tape has too many errors the software will freeze the the tape for you. ( I know also that if you had it write protected and try to write to it, it can also get frozen but we don't leave tapes in the robot over night that were used for restores).
When I check backups in the morning I look for bad tapes (via errors or the Problems report) and we also put a note on the tape when taken out to put it in the "bad box" when it expires.
True we may miss doing this some days.
When we put tapes back into the robot at the end of the two weeks or six months, we know all the tapes we are putting in should be expired.
so all tapes in the robot should be expired.
if we sort media in the gui by assigned time and robot if we see any that are still assigned.....
the first thing we do is compare them to the Tape Summary report.
if the report says it is frozen and past the expire date then we have to assume that the tape may have been bad. At which point we take it out and put it in the bad box.
At some time in the furture, we have Media Recovery clean and recertify the tapes. If they pass we use them again. If they don't pass we have the destroyed.
