SCSI QIC Tape Woes

[Thomas Benedict]

Here's my problem:

We have a tape that has multiple tar format archives written to it.
The way we did this was to skip to the end of tape, and then write an
archive.  Simple 'nuff.  The problem is that the mt utility in IRIX
seems to have a little glitch.  If you do an mt feom using
/dev/nrtapens it will happily whirrrrr over to the end of tape, then
happily rewind itself, then VERY happily tell you you are at the end
of tape.

So our intrepid researcher skipped to the end (beginning) of tape and
wrote his new backup, handily overwriting the beginning of his tape.
He didn't overwrite a whole lot.  Maybe 20 meg tops.  So there's still
around 80 meg of good data on the tape... only it's past the end of
tape marker.

Does anyone know how to get past the end of tape marker on an SGI QIC
tape drive?  It's the standard SCSI Viper 150 tape that you get with
your machine.

Tom Benedict
benedict at chaos.utexas.edu
Center for Nonlinear Dynamics