REPORT LUNS mandatory SPC-3?

Peter Johansson PJohansson at acm.org
Sun Jul 28 14:26:14 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* Peter Johansson <PJohansson at ACM.org>
*
At 02:01 PM 7/28/2002 -0700, Matthew Jacob wrote:

>Can you say more why you believe REPORT LUNS is inappropriately placed in 
>SPC-3?

i) Why should a device that implements only LU zero be required to support 
REPORT LUNS?

ii) In the SBP-3 working group, we are discussing hybrid devices whose 
medium may be accessible either by consumer electronics command sets (such 
as AV/C, developed by the 1394 Trade Association) or by SCSI commands (such 
as RBC or SBC). So far, we think the simplest way to make medium usually 
under the control of AV/C available for access by RBC commands is to 
temporarily instantiate a LU with an RBC device type and access restricted 
to the relevant portion of the medium. The usefulness of this scheme might 
be defeated if we were required to report these ephemeral LUNs via REPORT 
LUNS, since the initiator's operating system might claim exclusive control 
ahead of the application that desired access to the medium.

I hope that argument i) is sufficiently persuasive on its own; I've 
provided ii) only as an additional example as to why REPORT LUNS is not 
necessarily useful or desired in all environments.


Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

PJohansson at ACM.org

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