Subject: Re: mt driver and 7979A ?
To: Michael Wolfson <>
From: Jarkko Teppo <>
List: port-hp300
Date: 06/01/1999 10:53:10
Michael Wolfson wrote:

>ISTR that zero is normal mode (reads one block at a time), 8 is "streaming"
>(much faster if your tape drive supports this).  Not quite sure about 4 and
>:)I tried almost every combination of mt -f /dev/rmt[insert number here]
>:)but no go. I always get "can't get stat.... bp== NULL" (hazy memory).
>Could be that your tape drive doesn't support the stat command.  >Remember,
>the mt program is also used for much newer tape drives (like DAT) so >some
>features might not be available.

I'm not sure about that, since I have no manual and the only source of
information is dev/mt.c and dev/mtreg.h.

And for the daily dose of unscientific experimental results:
Power on the hard drives (SCSI and HPIB), 9144 ct and 7979A. The 7979A is
all alone in the fast HP-IB bus. After powering up the peripherals I boot
the system (single user) and try:
# dd if=/dev/nrmt8 of=/usr/tmp/testi bs=20b
(some error messages like can't stat bp==NULL)
#dd if=/dev/nrmt8 of=/usr/tmp/testi bs=20b
mt0:not online blablablaa

Then I take the drive offline, unload the tape, cycle the power to the drive
and load the tape:
#dd if=/dev/nrmt8 of=/usr/tmp/testi bs=20b
followed by approx. seven seconds of activity, the tape drive displaying
"reading", a short rewind and tape drive showing "idle" ie. waiting for
Meanwhile dd has gone into lala-land, transforming itself into an immortal
process, unkillable even with -9. No error messages, nothing.

The same thing happens with /dev/nrmt0 and /dev/rmt0. Now I am *absolutely
uncertain* about the parameters to dd, so if anyone wants to help just mail

>:)One problem might be the configuration, because I got the drive from an
>:)HP3000 system and I didn't get any documentation with it.
>Good luck,
>  -- MW

ps. browsing through the mail-index I found that the mt driver was
introduced in NetBSD 1.1 and in the announcement there was a call for
testers. Just curious, am I the first one to try this ?

Jarkko Teppo