You can do this:

select * from volhistory where volume_name='D00190'

to find out how the tape was used last.


Another thing to try:

q actlog begindate=today-10 search=D00190

to see what has happened to that tape in the last 10 days.
What sometimes happens:  If TSM has trouble mounting a scratch tape (due to
problems with the robot or problems with the drive or problems with the tape
itself)  it will automatically mark the tape as PRIVATE so it doesn't go
after the tape again on the next scratch request.  If the actually problem
was caused by the robot or the drive, once that problem is resolved, you
just change the status back to scratch since there never was anything really
wrong with the tape.

If there is no valid data on the tape, and you don't think there is anything
wrong with it, you can change it back to scratch with:

update libv 3494LIB D00190 status=scratch