Question regarding OIR bit

Roger Cummings roger_cummings at symantec.com
Thu Apr 20 09:47:15 PDT 2006


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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 at symantec.com
  _____  
From: Banther, Michael [mailto:michael.banther at hp.com] 
Sent: Tuesday, April 18, 2006 12:10 PM
To: Roger Cummings
Cc: t10 at 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:
	*	
		The first sentence applies to a command received from an
I_T nexus when that I_T nexus does not hold a reservation (including a
persistent reservation) but some other I_T nexus does hold one.
	*	
		The second sentence applies to a command received from
an I_T nexus when neither that I_T nexus nor any other I_T nexus holds a
reservation.
	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



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