[1314] in linux-scsi channel archive
Re: Media changer
daemon@ATHENA.MIT.EDU (Andy Poling)
Sun Jan 26 12:26:47 1997
Date: Sun, 26 Jan 1997 12:24:31 -0500 (EST)
From: Andy Poling <andy@realbig.com>
To: Dan Merillat <Dan@Merillat.org>
cc: Linux SCSI List <linux-scsi@vger.rutgers.edu>
In-Reply-To: <Pine.LNX.3.95.970126034721.346A-100000@chaos.ao.net>
On Sun, 26 Jan 1997, Dan Merillat wrote:
> Oh, and in addition to my previous message, I installed scsi generic in my
> kernel and it reports:
>
> Vendor: ARCHIVE Model: Python 28849-XXX Rev: 4.CM
> Type: Sequential-Access ANSI SCSI revision: 02
> Detected scsi tape st0 at scsi0, channel 0, id 5, lun 0
> scsi: unknown type 8
> Vendor: ARCHIVE Model: Python 28849-XXX Rev: 4.CM
> Type: Medium Changer ANSI SCSI revision: 02
> Detected scsi generic sgd at scsi0, channel 0, id 5, lun 1
> scsi : detected 1 SCSI tape 2 SCSI disks total.
> resize_dma_pool: unknown device type 8
>
> Anyone have a Medium Changer program?
There are SCSI commands specifically for changers, but I can say from
experience that the manufacturer has their own interpretation of exactly
what should happen for each of those commands.
I wrote a controller program (it basically moved a tape from here to there
and showed where tapes were) about a year ago for the HP 1533 six-cartridge
internal DAT changer that ran on SGI IRIX systems (their generic SCSI
support is not all that different form Linux's). It's not all that hard,
but you really need the manufacturer's technical documentation (this was
essential in my HP changer effort) and some experimentation with the
specific changer you want to control. For example, I found that the above
mentioned changer would easily get jammed if I didn't wait sufficiently long
between movement commands. Just because it says it's ready doesn't mean it
actually *is* ready. 1/2 :-)
Alas I no longer work where I wrote that software so I no longer have access
to it.
Someone else mentioned this but your best bet is to see if you can put the
changer into "stacker" mode, where every time you eject a tape, it
automatically loads the next tape. That still leaves up to you the headache
of your software knowing when to eject the tape. As I recall, I did this by
piping the output of the backup software to a program that looked to the
backup software like "dd" or "cat" but also changed the tape when it ended.
Note that you'll need an equivalent version for reading.
-Andy
Global Auctions
