Re: SCSI Autoloaders

Jeremy A. Gilbert (
Wed, 9 Jul 1997 09:19:32 -0400 (EDT)

> I have been poking around in the manpages for mt(1) and st(4), and
> linux/drivers/scsi/, and I don't see any ioctl for switching
> tapes in an autoloader. I recently purchased a Seagate 4586NP SCSI-2 DAT
> autoloader recognized as:

A kernel level driver is not technically neccesary. I have written
several user-level drivers (for IRIX mostly, but one for Linux) which
issue the apporpriete SCSI-2 commands to control a magazine changer. As
long as the OS in question supports the generic scsi interface, it is a
relativly simple matter since these are documented commands. At present,
I have source code I've written for IRIX to control a HP DDS-2 Autoloader
and a Quantum DLT/4500. Porting to Linux should be a snap. Once you know
the right incantation for a particular OS to send a n-byte command out on
the bus to a particular ID and whatnot, the rest is relativly trivial. You
may have to figure out exactly what command set your device uses --some
devices, like the HP, don't seem to support the MOVE MEDIUM et. al.
commands, and instead use extra arguments to the LOAD/UNLOAD command.

I can give you references to the SCSI-1/2 specification on the web
as well as the source code collection I mentioned before. Anyone who is
interested, just mail me.

I wouldn't recommend writing a kernel level driver for this. But
you might want to bring it up with the folks on linux-scsi (which I am not
subscribed to) and see what they think.


Jeremy Gilbert +
Webmaster & UNIX Systems Support +
Department of Computer Science +
Brandeis University +