CAP SPC-3 LB discussion topic - REPORT LUNS and PQ/PDT 7Fh

Ralph Weber roweber at IEEE.org
Thu Jan 13 10:03:56 PST 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <roweber at ieee.org>
*
Seeing no evidence that the topic discussed in the e-mail messages below
has been resolved, I request that John add a new 5.2.x CAP agenda item
titled REPORT LUNS and peripheral qualifier/device type 7Fh

Those with axes to grind on the subject, please warm up your grindstones
before the meeting. Note that if my reading the the tea leaves is right,
this topic cannot be resolved by a reflector discussion prior to the
meeting.

Thanks,

.Ralph


-------- Original Message --------
Subject: 	Re: SPC-3 REPORT LUNS and PQ/PDT 7Fh
Date: 	Wed, 24 Nov 2004 16:00:18 -0600
From: 	Charles Binford <Charles.Binford at Sun.COM>
To: 	Elliott, Robert (Server Storage) <elliott at hp.com>
CC: 	George Penokie (IBM) <gop at us.ibm.com>, Ralph Weber (ENDL) 
<roweber at ieee.org>
References: 
<78AF3C342AEAEF4BA33B35A8A15668C606E39DA8 at cceexc17.americas.cpqcorp.net>



Yep, I think we have a hole.  My initial response would be that Report 
Luns essentially ignores the LUN in the request and always reports the 
LU list for the initiator.  Based on what George was arguing for during 
the CAP meeting I doubt he would like that approach.

So, if I consider his line of thinking on the subject it seems we need 
something along the lines of:

    * if addressed to lun 0, even if lun 0 doesn't exist, Target must
      report the data
          o need this for compatibility
    * if addressed to the Report Luns Well Know Lun, and the target
      doesn't support WKLuns, the target *may* give Illegal Request or
      report the data
    * if addressed to any other LU that doesn't exist, the target *may*
      give Illegal Request, or report the data
    * if addressed to any other LU that does exist- ????  I'd say report
      the data, but if I heard George correctly, he'd argue for an error
      since the a generic LU may not know about all of the other LUs

I doubt this will fly :-), but it gives a straw horse to pick at.
cb


Elliott, Robert (Server Storage) wrote:

>This was touched on in the last meeting.
>
>SAM-3 5.9.4 says:
>"The SCSI target device's response to an incorrect logical unit number is
>described in this subclause. 
>
>In response to a REQUEST SENSE command, a REPORT LUNS command, or an INQUIRY
>command the SCSI target device shall respond as defined in SPC-3.
>
><all other commands return CHECK CONDITION/ILLEGAL REQUEST/LOGICAL UNIT NOT
>SUPPORTED>"
>
>But SPC-3 does not define the response for all three:
>1) REQUEST SENSE is clear: "In response to a REQUEST SENSE command issued to
>a logical unit that the SCSI target device does not support the device
>server shall return GOOD status and parameter data that contains sense data.
>The sense key shall be set to ILLEGAL REQUEST and the additional sense code
>shall be set to LOGICAL UNIT NOT SUPPORTED."  (I have a letter ballot
>comment asking that 011b/1Fh be mentioned there)
>
>2) INQUIRY is clear: "If the SCSI target device is not capable of supporting
>a peripheral device connected to this logical unit, the device server shall
>set these fields to 7Fh (i.e., PERIPHERAL QUALIFIER field set to 011b and
>PERIPHERAL DEVICE TYPE field set to 1Fh)."
>
>3) REPORT LUNS doesn't mention what to do.  Is it required that the command
>be processed or not?
>
>
>  
>

-- 
Charles Binford
Sun Microsystems
Wichita, KS 67226
316.315.0382 x222



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