Re: Using tape autochanger?

In article <45b8d5ec$0$67886$dbd45001@xxxxxxxxxxxxxxx>,
Frank Slootweg <this@xxxxxxxxxxxxxxxxx> writes:
Steve Allen <allen@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
0/3/1/0/4/1.0.0 schgr HP MSL6000 Series (Autochanger)
0/3/1/0/4/1.1.0 stape HP Ultrium 3-SCSI (Tape Device)

That says to me that the system is recognizing it as a tape library and a
tape drive.
What SAM *displays* is *not* "recognizing". It just displays what the
device answers when you send it a SCSI describe (or whatever) command.

Huh. I had no idea that the devices were so verbose. But then, when I
use the `mt status` command on IRIX (which is considerably more informative
than its HP counterpart), it tells me, among other things:
Device: QUANTUM: DLT7000 1E48qH
and `hinv` tells me:
Jukebox: unit 4 on SCSI controller 2
Tape drive: unit 5 on SCSI controller 2: DLT

I rather doubt that "Jukebox" and "Autochanger" are part of the device ID
string returned in response to a query. I imagine that the query must
return a code that is then interpreted by the system to determine the
device type. And the code for "changer" doesn't differentiate between
MO and tape type robots.

Not necessarily through the pass-thru device.
Indeed. IIRC, SAM and ioscan(1M) and friends use the diag driver to
get their *hardware* information.

Ah.

It creates a device node for it in /dev/rac (which I take to be for
Raw Auto Changer, along the lines of rdsk, rmt and rscsi).
My memory is becoming a little vague on this, but I'm quite sure that
that is because your kernel contains the schgr driver. The schgr driver
is for a changer, but not for a *tape* changer. It is (mainly was) for a
MO (Magneto-Optical) *disk* changer, which are hardly used anymore.

Yes, I do recall the man page for autochanger talking exclusively about
MO devices. But mc talks about tapes, though it does mention the -p device
option, for pass-though device, and that is where it lost me.

'solution' gets rid of the "UNKNOWN" and "UNCLAIMED", so far so good,
but it also lists "schgr" as the driver associated with the tape
changer, i.e. it lists the *wrong* driver, because schgr is for a *disk*
changer. Catch-22.)

Following some googling, I located and installed an IBM tape library control
program, which replaced the "schgr" driver with "atdd", but I couldn't get
that to work -- probably still needed the pass-through device, or it works
only with IBM changers... But it's no longer on the system.

I just fail to see why mc cannot use the device /dev/rac/c5t0d0, but I
instead have to create a pass-thru device for it... Or to put it
another way, what is /dev/rac/c5t0d0 good for?
See above. Please do a "lssf /dev/rac/c5t0d0" (and post the output).
I'm quite sure that it will list schgr as the driver.

Yes:
# lssf /dev/rac/c5t0d0
schgr card instance 5 SCSI target 0 SCSI LUN 0 control at address 0/3/1/0/4/1.0.0 /dev/rac/c5t0d0

BTW, don't use ls(1), mknod(1M) (except when *specifically* told
so, i.e. in the case of scsi_ctl(7)) and rm(1) for device files. For
device files you use the *sf(1M) commands, i.e. lssf, mksf, insf, rmsf.

Yes, I have noted those commands. Hopefully, the next time I need to use
them, it will be at the direction of some well-documented install procedure.
;-)

I hope this helps.

It does. Thank you very much.

Steve
.

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