Roger and Michael,

My memory is that the OIR is set to Guarantee that when the I_T Nexus on which a command is received does not hold a reservation the command receives a CC telling that I_T Nexus that it does not hold a reservation.  There was no other intent here than guaranteeing that the initiator in question holds a reservation before allowing commands to be processed.

If an initiator gets a reservation conflict, he will not be allowed to do I/O and knows that somebody else has the LUN reserved.  If an initiator gets a "not reserved" he knows that he must reserve the LUN.  I guess the question comes down to if the desired behavior of the system is to make the host get "not reserved" then reservation conflict when he tries to reserve.  However, if the device server is supposed to respond with "not reserved" for every reservation conflict eligible command then reserve would also get it and be broken.  I think this dictates that the desired behavior should be:
If a different I_T Nexus has the LUN reserved, return Reservation Conflict, else if the I_T Nexus through which the command is received does not hold a reservation, then return CC with "Not Reserved".

Thanks,

Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/


"Roger Cummings" <roger_cummings@symantec.com>
Sent by: owner-t10@t10.org

04/20/2006 09:47 AM

To
"Banther, Michael" <michael.banther@hp.com>
cc
<t10@t10.org>, "Casado, Reyes" <reyes.casado@hp.com>, "Greg Wheeless" <greg_wheeless@symantec.com>
Subject
RE: Question regarding OIR bit





Michael,
 
I've searched both my memory and my archive, and neither has been very enlightening on this subject.
 
What I can tell you is that the current wording was not in the r0 of the OIR proposal, but appeared in r1 after the initial proposal was presented at the September 2003 CAP meeting. The minutes confirm that changes were requested as that meeting, and my notes from then have reference to needing to include the phrase "an I_T nexus not holding" and define which commands the bit applies to, but that's all. After r1 the text is essentially unchanged until the r4 that was approved for inclusion in SSC-3.
 
I believe that the intent here is that the 2nd and 3rd sentence describe the same situation, namely that if the OIR bit is set to one, and and a command is received for logical unit upon which no reservation or persistent reservation exists, then the response is a CHECK CONDITION with "Not Reserved".
 
I don't believe that your interpretation of the sentences as describing different situations works, because in the first bullet the response would be a Reservation Conflict, and that is not related to what is being addressed in the OIR description.
 
Note that the second sentence only says "no reservation exists", while the 3rd says "no reservation or persistent reservation exists". I wonder if the wording is and attempt to cover the use of the OIR bit with both SPC-2 and SPC-3 compliant devices. Sorry, that's the only constructive suggestion I can make - does anybody else have other ideas or memories?
 
Regards,
 
 
 
 
Roger Cummings
SYMANTEC
 
roger_cummings@symantec.com

From: Banther, Michael [mailto:michael.banther@hp.com]
Sent: Tuesday, April 18, 2006 12:10 PM
To: Roger Cummings
Cc: t10@t10.org; Casado, Reyes
Subject: Question regarding OIR bit
Hi Roger,
 
In SSC-3r02, clause 8.3.3, the definition of the OIR bit has caused some confusion here:
If the only if reserved (OIR) bit is set to one, the device server shall process a command only if a reservation (see SPC-2) or persistent reservation (see SPC-3) exists that allows access via the I_T nexus from which the command was received. If the OIR bit is set to one and a command is received from an I_T nexus for which no reservation exists, the device server shall not process the command. If the OIR bit is set to one and a command is received from an I_T nexus for a logical unit upon which no reservation or persistent reservation exists, the device server shall terminate the command with CHECK CONDITION status. The sense key shall be set to ILLEGAL REQUEST and the additional sense code shall be set to NOT RESERVED.
We're not sure whether you intended the second a third sentences above to describe the same situation or two slightly different situations.  I read it that these two sentences describe two different situations: However it's possible to interpret that second sentence as an introduction to the specifics of the third sentence, in which case they refer to the same situation.  Could you please clarify the intention?
 
Michael Banther
Hewlett-Packard Ltd.
Telephone +44 (117) 312-9503