[3519] in linux-scsi channel archive
Re: HP DAT autochanger
daemon@ATHENA.MIT.EDU (Andy Poling)
Fri Mar 13 13:36:26 1998
Date: Fri, 13 Mar 1998 12:48:28 -0500 (EST)
From: Andy Poling <andy@globalauctions.com>
To: "Gerald J. Puhl" <garyp@jppattern.com>
cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <Pine.LNX.3.96.980313090048.9962A-100000@garyp.jppattern.com>
On Fri, 13 Mar 1998, Gerald J. Puhl wrote:
> According to the HP manual the SCSI command LOAD/UNLOAD
> (opcode 0x1b) is used to load or unload a specified cartridge from the
> drive mech. After reviewing the SCSI-Programming howto and downloading
> some the SPECS on SCSI-2 that doesn't appear to be correct. If fact the
> MOVE MEDIUM command should be used and that the LOAD command merely
> enables the drive. Does anyone know the proper command sequence to do
> this?
I wrote driver software for an HP DAT changer (1535 maybe?) in a former
life, so I'll try to remember how it worked...
As I recall, the MOVE MEDIUM command moves a cart from here to there, but if
"here" is the drive then it must be UNLOADed first. The UNLOAD spits the
tape out of the drive so that the changer can snag it. As I recall the LOAD
command was harmlessly redundant, as the move would load the drive.
HP provides two command sets to do this sort of thing. One is custom stuff
that lets you combine some operations, while the other is pretty standard
changer ops.
A word of warning. I found that MOVE MEDIUM commands would return before
the changer had actually completed them. And if I tried another command
right away, the changer would get out of synch and just return NOT READY to
any command until you ejected the whole damn magazine and re-inserted it to
start over again. I eventually laced the damn driver with generous sleep()s
to avoid trips to the remote machine room...
Good luck!
-Andy
Global Auctions
http://www.globalauctions.com
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