SPC-3 PR Question

George Penokie gop at us.ibm.com
Mon Nov 17 12:19:37 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* George Penokie <gop at us.ibm.com>
*
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Charles. 

The wording in section 5.6.2.7.4.4 and in the flowchart (as soon as it
is fixed per 03-253) indicates that the registration is removed. This is
no exception stated for the case you describe where the key that is sent
on a preempt is the same as the key for the I_T nexus receiving the PR
command. 

I do agree that this is an interesting anomaly in that, if the
reservation was held by the I_T nexus being preempted both the
reservation and registration remain but if there is no reservation held
by the I_T nexus being preempted then the registration is removed.
However, that's the way it's described and presumably implemented. So a
few words making that clear may be in order.

Bye for now,
George Penokie

Dept 2C6  114-2 N212
E-Mail:    gop at us.ibm.com
Internal:  553-5208
External: 507-253-5208   FAX: 507-253-2880





	Charles Binford <Charles.Binford at Sun.COM> 
Sent by: Charles.Binford at Sun.COM 


11/17/2003 01:25 PM 
        
        To:        "'Ulrich, David'" <dulrich at lsil.com> 
        cc:        George Penokie/Rochester/IBM at IBMUS 
        Subject:        RE: SPC-3 PR Question 





David,  George had sent me direct email asking whether or not I got my
answer.  I'm cc'ing him on this as an example of someone else who finds
this scenario ambiguous in the current spec. 
  
George,  I'm thinking we should add a sentence or two to SPC-3 in this
clause to clarify things.  Your comments on the subject welcome... 
  
  

Charles Binford 
Sun Microsystems 
316.315.0382 x222 


-----Original Message-----
From: Ulrich, David [mailto:dulrich at lsil.com] 
Sent: Monday, November 17, 2003 1:07 PM
To: 'Charles Binford'
Subject: RE: SPC-3 PR Question

Hi Charles, 
  
After further review I think a definitive answer to your question is in
order.  The wording of 5.6.2.7.4.4 as follows: 
  
"If there is a persistent reservation and if the SERVICE ACTION
RESERVATION KEY field does not identify a persistent 
reservation holder the device server shall perform a preempt by doing
the following in an uninterrupted series of 
actions: 
  
a) Remove the registration for the I_T nexus or I_T nexuses identified
by the SERVICE ACTION RESERVATION KEY field; 
b) Ignore the contents of the SCOPE and TYPE fields; 
c) Process tasks as defined in 5.6.1; and 
d) Establish a unit attention condition for any initiator port
associated with an I_T nexus that lost its registration 
other than the initiator port that sent the PERSISTENT RESERVE OUT
command. The sense key 
shall be set to UNIT ATTENTION and the additional sense code shall be
set to REGISTRATIONS 
PREEMPTED." 
  
doesn't say anything about excluding the preempting initiator or
establishing a registration for the preempting initiator after removing
its registration.  The implication of step d could be construed that the
registration was removed and so the specific instruction to exclude it
|from a UA is required. 
  
The flowchart in section 5.7.6.2.4.1 doesn't shed any additional light
on this question either. 
  
As the sections in question stand now, I think they may be construed to
mean that it is possible to remove your own key with a preempt service
action.  If this isn't the intent then I think specific wording should
be introduced for clarification. 
  
Best Regards, 


David Ulrich 
Staff Software Engineer 
LSI Logic Storage Systems 
3718 N. Rock Road 
(316) 636-8871 
david.ulrich at lsil.com 
www.lsilogicstorage.com 


LSI Logic Storage Systems 
AT THE HEART OF INFORMATION 


  
-----Original Message-----
From: Charles Binford [mailto:Charles.Binford at sun.com]
Sent: Friday, November 14, 2003 1:24 PM
To: 'T10 Reflector'
Cc: Henderson, Steve
Subject: SPC-3 PR Question



All, I have a question on whether or not a Registration is removed when
an Initiator uses Preempt on his own Key.  I'm reading SPC-3 Revision
15.  In the section where Preempt Key matches a reservation holder the
text clearly says the registration is not cleared. 


5.6.2.7.4.3 Preempting persistent reservations and registration handling
...
If the SERVICE ACTION RESERVATION KEY identifies a persistent
reservation holder....
...
A PERSISTENT RESERVE OUT with a PREEMPT service action or a PREEMPT AND
ABORT service action with the SERVICE ACTION RESERVATION KEY value equal
to the persistent reservation holder's reservation key is not an error.
In that case the device server shall establish the new persistent
reservation and maintain the registration. 


However, in the next section where the Preempt Key does NOT match the
persistent reservation holder the text merely says "It is not an error".



5.6.2.7.4.4 Removing registrations
...
If there is a persistent reservation and if the SERVICE ACTION
RESERVATION KEY field does not identify a persistent reservation
holder....
...
It is not an error for a PERSISTENT RESERVE OUT with a PREEMPT service
action or a PREEMPT AND ABORT service action to set the RESERVATION KEY
and the SERVICE ACTION RESERVATION KEY to the same value, however, no
unit attention condition is established for the initiator port that sent
the PERSISTENT RESERVE OUT. 


My assumption is that one can never remove your own registration with a
preempt (you register with a zero key), but I'm having trouble finding
words that clearly back up that statement for all cases. 
  
Thanks, 
  
Charles Binford 
Sun Microsystems 
316.315.0382 x222 
  




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<br><font size=2 face="sans-serif">Charles.</font>
<br>
<br><font size=2 face="sans-serif">The wording in section 5.6.2.7.4.4 and in the flowchart (as soon as it is fixed per 03-253) indicates that the registration is removed. This is no exception stated for the case you describe where the key that is sent on a preempt is the same as the key for the I_T nexus receiving the PR command. </font>
<br>
<br><font size=2 face="sans-serif">I do agree that this is an interesting anomaly in that, if the reservation was held by the I_T nexus being preempted both the reservation and registration remain but if there is no reservation held by the I_T nexus being preempted then the registration is removed. However, that's the way it's described and presumably implemented. So a few words making that clear may be in order.<br>
<br>
Bye for now,<br>
George Penokie<br>
<br>
Dept 2C6 &nbsp;114-2 N212<br>
E-Mail: &nbsp; &nbsp;gop at us.ibm.com<br>
Internal: &nbsp;553-5208<br>
External: 507-253-5208 &nbsp; FAX: 507-253-2880<br>
<br>
</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>Charles Binford <Charles.Binford at Sun.COM&gt;</b></font>
<br><font size=1 face="sans-serif">Sent by: Charles.Binford at Sun.COM</font>
<p><font size=1 face="sans-serif">11/17/2003 01:25 PM</font>
<br>
<td><font size=1 face="Arial">&nbsp; &nbsp; &nbsp; &nbsp; </font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; To: &nbsp; &nbsp; &nbsp; &nbsp;"'Ulrich, David'" <dulrich at lsil.com&gt;</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; cc: &nbsp; &nbsp; &nbsp; &nbsp;George Penokie/Rochester/IBM at IBMUS</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; Subject: &nbsp; &nbsp; &nbsp; &nbsp;RE: SPC-3 PR Question</font>
<br></table>
<br>
<br>
<br><font size=2 color=#008000 face="Tahoma">David, &nbsp;George had sent me direct email asking whether or not I got my answer. &nbsp;I'm cc'ing him on this as an example of someone else who finds this scenario ambiguous in the current spec.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=#008000 face="Tahoma">George, &nbsp;I'm thinking we should add a sentence or two to SPC-3 in this clause to clarify things. &nbsp;Your comments on the subject welcome...</font>
<br><font size=3>&nbsp;</font>
<br><font size=3>&nbsp;</font>
<p><font size=2 face="Arial">Charles Binford</font><font size=3> </font><font size=2 face="Arial"><br>
Sun Microsystems</font><font size=3> </font><font size=2 face="Arial"><br>
316.315.0382 x222</font><font size=3> </font>
<p><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> Ulrich, David [mailto:dulrich at lsil.com] <b><br>
Sent:</b> Monday, November 17, 2003 1:07 PM<b><br>
To:</b> 'Charles Binford'<b><br>
Subject:</b> RE: SPC-3 PR Question<br>
</font>
<br><font size=2 color=blue face="Arial">Hi Charles,</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">After further review I think a definitive answer to your question is in order. &nbsp;The wording of 5.6.2.7.4.4 as follows:</font>
<br><font size=3>&nbsp;</font>
<br><font size=2>"If there is a persistent reservation and if the SERVICE ACTION RESERVATION KEY field does not identify a persistent</font>
<br><font size=2>reservation holder the device server shall perform a preempt by doing the following in an uninterrupted series of</font>
<br><font size=2>actions:</font>
<br><font size=3>&nbsp;</font>
<br><font size=2>a) Remove the registration for the I_T nexus or I_T nexuses identified by the SERVICE ACTION RESERVATION KEY field;</font>
<br><font size=2>b) Ignore the contents of the SCOPE and TYPE fields;</font>
<br><font size=2>c) Process tasks as defined in 5.6.1; and</font>
<br><font size=2>d) Establish a unit attention condition for any initiator port associated with an I_T nexus that lost its registration</font>
<br><font size=2>other than the initiator port that sent the PERSISTENT RESERVE OUT command. The sense key</font>
<br><font size=2>shall be set to UNIT ATTENTION and the additional sense code shall be set to REGISTRATIONS</font>
<br><font size=2>PREEMPTED."</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">doesn't say anything about excluding the preempting initiator or establishing a registration for the preempting initiator after removing its registration. &nbsp;The implication of step d could be construed that the registration was removed and so the specific instruction to exclude it from a UA is required.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">The flowchart in section 5.7.6.2.4.1 doesn't shed any additional light on this question either.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">As the sections in question stand now, I think they may be construed to mean that it <u>is</u> possible to remove your own key with a preempt service action. &nbsp;If this isn't the intent then I think specific wording should be introduced for clarification.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">Best Regards, </font>
<p><font size=1 color=#000080 face="Comic Sans MS">David Ulrich</font><font size=2 color=blue face="Arial"> </font><font size=1 color=#000080 face="Comic Sans MS"><br>
Staff Software Engineer</font><font size=2 color=blue face="Arial"> </font><font size=1 color=#000080 face="Comic Sans MS"><br>
LSI Logic Storage Systems</font><font size=2 color=blue face="Arial"> </font><font size=1 color=#000080 face="Comic Sans MS"><br>
3718 N. Rock Road</font><font size=2 color=blue face="Arial"> </font><font size=1 color=#000080 face="Comic Sans MS"><br>
(316) 636-8871</font><font size=2 color=blue face="Arial"> </font><font size=1 color=#000080 face="Comic Sans MS"><br>
david.ulrich at lsil.com</font><font size=2 color=blue face="Arial"> </font><font size=2 color=blue face="Courier New"><br>
www.lsilogicstorage.com</font><font size=2 color=blue face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">LSI Logic Storage Systems</font><font size=2 color=blue face="Arial"> </font><font size=2 color=#000080 face="Arial"><br>
A</font><font size=1 color=#000080 face="Arial">T THE</font><font size=2 color=blue face="Arial"> </font><font size=2 color=#000080 face="Arial">H</font><font size=1 color=#000080 face="Arial">EART OF</font><font size=2 color=blue face="Arial"> </font><font size=2 color=#000080 face="Arial">I</font><font size=1 color=#000080 face="Arial">NFORMATION</font><font size=2 color=blue face="Arial"> </font>
<p><font size=3>&nbsp;</font>
<br><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> Charles Binford [mailto:Charles.Binford at sun.com]<b><br>
Sent:</b> Friday, November 14, 2003 1:24 PM<b><br>
To:</b> 'T10 Reflector'<b><br>
Cc:</b> Henderson, Steve<b><br>
Subject:</b> SPC-3 PR Question<br>
</font>
<p><font size=2 color=blue face="Tahoma">All, I have a question on whether or not a Registration is removed when an Initiator uses Preempt on his own Key. &nbsp;I'm reading SPC-3 Revision 15. &nbsp;In the section where Preempt Key matches a reservation holder the text clearly says the registration is not cleared.</font>
<p><font size=2 face="Times New Roman"><b>5.6.2.7.4.3 Preempting persistent reservations and</b></font><font size=3 face="Times New Roman"><b> registration handling</b><br>
...<br>
If the SERVICE ACTION RESERVATION KEY identifies a persistent reservation holder....<br>
...<br>
A PERSISTENT RESERVE OUT with a PREEMPT service action or a PREEMPT AND ABORT service action with the SERVICE ACTION RESERVATION KEY value equal to the persistent reservation holder's reservation key is not an error. <b>In that case the device server shall</b> establish the new persistent reservation and <b>maintain the registration</b>.</font>
<p><font size=2 color=blue face="Tahoma">However,</font><font size=2 face="Arial"> </font><font size=2 color=blue face="Tahoma">in the next section where the Preempt Key does NOT match the persistent reservation holder the text merely says "It is not an error". &nbsp;</font>
<p><font size=3><b>5.6.2.7.4.4 Removing registrations</b><br>
...<br>
If there is a persistent reservation and if the SERVICE ACTION RESERVATION KEY field does not identify a persistent reservation holder....<br>
...<br>
It is not an error for a PERSISTENT RESERVE OUT with a PREEMPT service action or a PREEMPT AND ABORT service action to set the RESERVATION KEY and the SERVICE ACTION RESERVATION KEY to the same value, however, no unit attention condition is established for the initiator port that sent the PERSISTENT RESERVE OUT.</font>
<p><font size=2 color=blue face="Tahoma">My assumption is that one can never remove your own registration with a preempt (you register with a zero key), but I'm having trouble finding words that clearly back up that statement for all cases.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Tahoma">Thanks,</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 face="Arial">Charles Binford</font><font size=3> </font><font size=2 face="Arial"><br>
Sun Microsystems</font><font size=3> </font><font size=2 face="Arial"><br>
316.315.0382 x222</font><font size=3> </font>
<br><font size=3>&nbsp;</font>
<br>
<br>
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