For everyone:
60 meter tapes are DAT tapes (and not to be confused with DDS tapes) and while they use the same external case and tape size, the media was never designed to store computer data. The very first DDS drives would read and write to anything that would fit into the slot (60 or 90 meters). This was before the days of Media Recognition System where little holes were punched in the leader to identify the type of tape.
The reason for MRS is that DDS technology was emerging rapidly and as tapes got thinner and the stiffness and composition of the magnetic coating changed, it was highly likely that new, high density tapes would jam in the older drives. SO MRS would only allow tapes designed for the drive to be inserted. A DDS-3 tape is popped right back out from a DDS-2 drive as an example.
Since 60 meter tapes may have been used n the past (and DAT tapes have VERY HIGH error rates), firmware in DDS drives was changed to always treat 60 meter (non-MRS) tapes as always write protected. You don't want to EVER use DAT tapes for computer data.
True Digital Audio Tapes have extensive error correction to accomodate the error rate but also include a fill-in the gaps technique which works fine on music (a few milliseconds of lost data is replaced by the same information from a previous record), but is catastrophic for computer data.
So, read all your 60 meter tapes and capture the information onto DDS tapes, then discard them. It is also a good idea to use the term DDS rather than DAT since they are not the same.
Bill Hassell, sysadmin
