1) How come the character (raw) scsi tape device read and write routines are
 disabled (in the cdev switch)? The block read and write routines work.

2) I am running MRG, and playing with tapes. Doing a dump (or maybe trying
to read the dump tape to make sure it was ok) seems to have wiped out the 
root partition, had to rebuild it. Was using /dev/st0 (see question 1).

Haven't had problems lately running backups under macOS to that tape...so
I don't immediately think of hardware as the culprit. Am I getting out into
uncharted territory here?

Machine is mac IIx. Tape is HP 35450A DAT.

-mark