A persistent reservation question

George Penokie gop at us.ibm.com
Tue Jun 29 07:01:34 PDT 2004


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

If a persistent reservation has been established and the RESERVE command
(there is no such thing as a key on a RESERVE command) comes from either

a) An I_T nexus that is a persistent reservation holder; or 
b) An I_T nexus that is registered if a registrants only or all
registrants type persistent reservation is present. 
the response from the logical unit depends on what option the logical
unit has implemented. 

If the logical unit that has the persistent reservation has the CRH
(Compatible Reservation Handling) bit from the REPORT CAPABILITIES
service action set to zero then the response to the RESERVE command is
RESERVATION CONFLICT no matter who sent it or how it got there. 

If the logical unit that has the persistent reservation has the CRH
(Compatible Reservation Handling) bit from the REPORT CAPABILITIES
service action set to one then the response to the RESERVE command from:


a) An I_T nexus that is a persistent reservation holder; or 
b) An I_T nexus that is registered if a registrants only or all
registrants type persistent reservation is present 

is that the RESERVE(6) or RESERVE(10) command shall complete with GOOD
status, but no reservation shall be established and the persistent
reservation shall not be changed. That means that as far as the
initiator port that sent the RESERVE command is concerned it has a
reservation with that logical unit. So it can issue commands to it and
they will not be rejected with a RESERVATION CONFLICT. However, the real
reservation is still the original  registrants only or all registrants
type persistent reservation. So from the point of view of the logical
unit there has been not change to the persistent reservation (i.e., the
RESERVE command is essentially a no-op).  If the RESERVE is received
under conditions other than those listed in items a) or b) above, even
if the CRH bit is set to one, that RESERVE command will get a
RESERVATION CONFLICT. 

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





"MEHROTRA, VIVEK (STSD)" <vivek.mehrotra at hp.com> 
Sent by: owner-t10 at t10.org 


06/28/2004 04:03 PM 

To
<t10 at t10.org> 

cc

Subject
RE: A persistent reservation question

	





Hi Rob, 
  
After I look in the SPC-3 section 5.6.2, it still does not answer my
question. Actually I wanted to know, if a host has registered
persistently by sending SPC-3 PERSISTENT RESERVE OUT command with
REGISTER or REGISTER AND IGNORE EXISTING KEY service action, and then
the device device receives SPC-2 RESERVE command (with the same key)
|from this host, what should the device do in this case ? 
  
SPC-3r19 section 5.6.2 says "A RESERVE(6) or RESERVE(10) command shall
complete with GOOD status, but no reservation shall be established and
the persistent reservation shall not be changed ...". I am not clear
about what does the part "... and the persistent reservation shall not
be changed" means. Does this mean that we get a RESERVE (SPC-2) command
after the host is PERSISTENTLY RESERVED (using SPC-3 style reservation).
If this is true, then my question is different. 
  
Please advice, on what I am thinking is correct or incorrect. 
  
Thanks in advance 
  
Vivek Mehrotra 
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Elliott,
Robert (Server Storage)
Sent: Thursday, June 24, 2004 7:04 PM
To: t10 at t10.org
Subject: RE: A persistent reservation question

SPC-2, which defined both commands, requires that RESERVATION CONFLICT
status be returned. 
  
SPC-3, which considers RESERVE/RELEASE obsolete, allows them to be
treated as NOOPs in certain cases (see section 5.6.2 of revision 19, all
the revisions of 03-232, 02-483, and 02-231). 
  
-- 
Rob Elliott, elliott at hp.com 
Hewlett-Packard Industry Standard Server Storage Advanced Technology 
 <https://ecardfile.com/id/RobElliott>
https://ecardfile.com/id/RobElliott 

-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of
MEHROTRA, VIVEK (STSD)
Sent: Thursday, June 24, 2004 3:23 PM
To: t10 at t10.org
Subject: A persistent reservation question


Hi Folks, 


What is the best approach to handle the scenario, when a device is
registered for persistent reservation using SCSI 3 style PERSISTENT
RESERVE OUT command (expecting a same style command with RESERVE service
action), but receives a old style RESERVE command from the initiator. 


I didn't see SCSI specs talking about this anywhere ! 


Thanks in Advance 


Vivek Mehrotra 




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<br><font size=2 face="sans-serif">Vivek,</font>
<br>
<br><font size=2 face="sans-serif">If a persistent reservation has been
established and the RESERVE command (there is no such thing as a key on
a RESERVE command) comes from either </font>
<br><font size=2 face="sans-serif">a) An I_T nexus that is a persistent
reservation holder; or</font>
<br><font size=2 face="sans-serif">b) An I_T nexus that is registered if
a registrants only or all registrants type persistent reservation is present.</font>
<br><font size=2 face="sans-serif">the response from the logical unit depends
on what option the logical unit has implemented. </font>
<br>
<br><font size=2 face="sans-serif">If the logical unit that has the persistent
reservation has the CRH (Compatible Reservation Handling) bit from the
REPORT CAPABILITIES service action set to zero then the response to the
RESERVE command is RESERVATION CONFLICT no matter who sent it or how it
got there.</font>
<br>
<br><font size=2 face="sans-serif">If the logical unit that has the persistent
reservation has the CRH (Compatible Reservation Handling) bit from the
REPORT CAPABILITIES service action set to one then the response to the
RESERVE command from:</font>
<br>
<br><font size=2 face="sans-serif">a) An I_T nexus that is a persistent
reservation holder; or</font>
<br><font size=2 face="sans-serif">b) An I_T nexus that is registered if
a registrants only or all registrants type persistent reservation is present</font>
<br>
<br><font size=2 face="sans-serif">is that the RESERVE(6) or RESERVE(10)
command shall complete with GOOD status, but no reservation shall be established
and the persistent reservation shall not be changed. That means that as
far as the initiator port that sent the RESERVE command is concerned it
has a reservation with that logical unit. So it can issue commands to it
and they will not be rejected with a RESERVATION CONFLICT. However, the
real reservation is still the original &nbsp;registrants only or all registrants
type persistent reservation. So from the point of view of the logical unit
there has been not change to the persistent reservation (i.e., the RESERVE
command is essentially a no-op). &nbsp;If the RESERVE is received under
conditions other than those listed in items a) or b) above, even if the
CRH bit is set to one, that RESERVE command will get a RESERVATION CONFLICT.</font>
<br><font size=2 face="sans-serif"><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 width=40%><font size=1 face="sans-serif"><b>"MEHROTRA, VIVEK (STSD)"
<vivek.mehrotra at hp.com&gt;</b> </font>
<br><font size=1 face="sans-serif">Sent by: owner-t10 at t10.org</font>
<p><font size=1 face="sans-serif">06/28/2004 04:03 PM</font>
<td width=59%>
<table width=100%>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top><font size=1 face="sans-serif"><t10 at t10.org&gt;</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">RE: A persistent reservation
question</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=2 color=blue face="Arial">Hi Rob,</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">After I look in the SPC-3 section
5.6.2, it still does not answer my question. Actually I wanted to know,
if a host has registered persistently by sending SPC-3 PERSISTENT RESERVE
OUT command with REGISTER or REGISTER AND IGNORE EXISTING KEY service action,
and then the device device receives SPC-2 RESERVE command (with the same
key) from this host, what should the device do in this case ?</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">SPC-3r19 section 5.6.2 says "</font><font size=2 color=blue face="Helvetica">A
RESERVE(6) or RESERVE(10) command shall complete with GOOD status, but
no reservation shall be established and the persistent reservation shall
not be changed ...". I am not clear about what does the part "...
and the persistent reservation shall not be changed" means. Does this
mean that we get a RESERVE (SPC-2) command after the host is PERSISTENTLY
RESERVED (using SPC-3 style reservation). If this is true, then my question
is different.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Helvetica">Please advice, on what I am
thinking is correct or incorrect.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Helvetica">Thanks in advance</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Helvetica">Vivek Mehrotra</font>
<br><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> owner-t10 at t10.org [mailto:owner-t10 at t10.org] <b>On Behalf Of
</b>Elliott, Robert (Server Storage)<b><br>
Sent:</b> Thursday, June 24, 2004 7:04 PM<b><br>
To:</b> t10 at t10.org<b><br>
Subject:</b> RE: A persistent reservation question<br>
</font>
<br><font size=2 color=blue face="Arial">SPC-2, which defined both commands,
requires that RESERVATION CONFLICT status be returned.</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 color=blue face="Arial">SPC-3, which considers RESERVE/RELEASE
obsolete, allows them to be treated as NOOPs in certain cases (see section
5.6.2 of revision 19, all the revisions of 03-232, 02-483, and 02-231).</font>
<br><font size=3>&nbsp;</font>
<br><font size=2 face="Arial">--</font><font size=3> </font><font size=2 face="Arial"><br>
Rob Elliott, elliott at hp.com</font><font size=3> </font><font size=2 face="Arial"><br>
Hewlett-Packard Industry Standard Server Storage Advanced Technology</font><font size=3>
</font><font size=2 color=blue face="Arial"><u><br>
</u></font><font size=2 color=blue face="Arial"><u>https://ecardfile.com/id/RobElliott</u></font><font size=3>
</font>
<br>
<br><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> owner-t10 at t10.org [mailto:owner-t10 at t10.org] <b>On Behalf Of
</b>MEHROTRA, VIVEK (STSD)<b><br>
Sent:</b> Thursday, June 24, 2004 3:23 PM<b><br>
To:</b> t10 at t10.org<b><br>
Subject:</b> A persistent reservation question<br>
</font>
<p><font size=2 face="Arial">Hi Folks,</font><font size=3> </font>
<p><font size=2 face="Arial">What is the best approach to handle the scenario,
when a device is registered for persistent reservation using SCSI 3 style
PERSISTENT RESERVE OUT command (expecting a same style command with RESERVE
service action), but receives a old style RESERVE command from the initiator.</font>
<p><font size=2 face="Arial">I didn't see SCSI specs talking about this
anywhere !</font><font size=3> </font>
<p><font size=2 face="Arial">Thanks in Advance</font><font size=3> </font>
<p><font size=2 face="Arial">Vivek Mehrotra</font><font size=3> </font>
<p>
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