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From: olson@anchor.esd.sgi.com (Dave Olson)
Newsgroups: comp.unix.bsd,comp.unix.internals
Subject: Re: Writing a device driver for CDROM [ no subluns ]
Keywords: bsd devicedriver cdrom
Message-ID: <mqm9m68@zuni.esd.sgi.com>
Date: 3 Jul 92 05:55:55 GMT
References: <1992Jun20.152106.159@rai.juice.or.jp> <24289@dog.ee.lbl.gov> <12sps1INNs18@rodan.UU.NET> <24317@dog.ee.lbl.gov>
Sender: news@zuni.esd.sgi.com (Net News)
Organization: Silicon Graphics, Inc. Mountain View, CA
Lines: 27
In <24317@dog.ee.lbl.gov> torek@horse.ee.lbl.gov (Chris Torek) writes:
| In article <24289@dog.ee.lbl.gov> I added, as an aside,
| >>Despite the sub-LUN stuff in the SCSI standards, I have never seen any
| >>SCSI units that in turn drive sub-units. Nonetheless, this particular
| >>scheme should handle them.
|
| In article <12sps1INNs18@rodan.UU.NET> lidl@rodan.UU.NET (Kurt J. Lidl) writes:
| >Well, all those people out there with sun3 shoebox drives have the
| >hardware necessary to do that. The Adaptec board in these boxes [maps] ...
| >scsi id 0, lun 0 -> /dev/rsd0
| >scsi id 0, lun 1 -> /dev/rsd1
| >scsi id 1, lun 0 -> /dev/rsd2
| >scsi id 1, lun 1 -> /dev/rsd3
|
| That is target + LUN, not target + LUN + sub-LUN. The SCSI subunits
| are done with message bytes, so that you get 256 subunits per unit.
| Since there are 8 possible units, this gives you as many as 2048 subunits
| per target (times 7 targets => 14336 total units).
Subluns went away in the final versions of the SCSI 2 spec (they were only
in a few of the intermediate revs), so I doubt you ever will see any devices
that have them...
--
Let no one tell me that silence gives consent, | Dave Olson
because whoever is silent dissents. | Silicon Graphics, Inc.
Maria Isabel Barreno | olson@sgi.com