Extent reservations

Hallam, Ken J Ken.Hallam at unisys.com
Thu May 14 16:12:00 PDT 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* "Hallam, Ken J" <Ken.Hallam at unisys.com>
*
I can't speak for others, but here at Unisys on our mainframes, all file
locking is handled by the ULPs, (Upper Layer Protocols) and not
entrusted to I/O driver software. All our systems with multiple
Initiators that share files, also share communications paths external to
SCSI between Initiators and we've been doing it this way for many years
without ever relying on or using Reserve/Release SCSI commands. In
addition, as far as I am aware, no commercial disk drive vendor supports
the Extents option in Reserve/Release and none plan to offer it in the
new Persistent Reserve/Release commands. So go ahead and remove it Bob,
it won't break our hearts.

Ken Hallam
> ----------
> From: 	Joseph C. Nemeth[SMTP:jnemeth at concentric.net]
> Sent: 	Thursday, May 14, 1998 3:26 PM
> To: 	Bob Snively; t10 at Symbios.COM
> Cc: 	bob.snively at Eng.Sun.COM; lohmeyer at ix.netcom.com
> Subject: 	Re: Extent reservations
> 
> * From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
> * "Joseph C. Nemeth" <jnemeth at concentric.net>
> *
> 
> -----Original Message-----
> From: Bob Snively <Bob.Snively at Eng.Sun.COM>
> To: t10 at Symbios.COM <t10 at Symbios.COM>
> Cc: bob.snively at Eng.Sun.COM <bob.snively at Eng.Sun.COM>;
> lohmeyer at ix.netcom.com <lohmeyer at ix.netcom.com>
> Date: Wednesday, May 13, 1998 5:37 PM
> Subject: Extent reservations
> 
> 
> >* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted
> by:
> >* Bob Snively <Bob.Snively at Eng.Sun.COM>
> >*
> >
> >In accordance with the SCSI working group minutes:
> >
> >------------- Begin Included Message -------------
> >
> >6.14 Command Behavior Under Reservations (98-164r0) [Snively]
> >
> >Bob Snively asked for opinions regarding a proposal with respect to
> extent
> >reservations (in Reserve and Release).  After some discussion, the
> group
> >agreed that extent reservations could be made obsolete for Reserve,
> Release,
> >and Persistent Reservations.  Bob agreed to announce the proposal at
> the
> T10
> >Plenary and on the T10 Reflector.  Ralph Weber agreed to make the
> change in
> >SPC-2 without specific instructions from a written proposal, should
> T10
> decide
> >to make the change at all.
> >
> >------------- End Included Message -------------
> >
> >and in accordance with the SCSI plenary minutes:
> >
> >------------- Begin Included Message -------------
> >
> >10.3   Making Extent Reservations Obsolete [Snively]
> >
> >In the absence of any objections, T10 assigned the Chair an action
> item to
> >notify the T10 Reflector that T10 intends to make extent reservations
> obsolete
> >for both Reserve and Persistent Reserve commands in SPC-2.
> >
> >------------- End Included Message -------------
> >
> >
> >I am sending an announcement on this reflector to propose that extent
> >reservations be removed from the RESERVE, RELEASE, PERSISTENT RESERVE
> IN,
> and
> >PERSISTENT RESERVE OUT commands.
> >
> >Please address any comments on this proposal to the entire reflector,
> copying
> >me and John Lohmeyer directly.
> 
> 
> I'm puzzled. If no one is using this, how to multiple initiators
> currently
> "share" a disk? Do they just grab the entire disk with a LUN reserve,
> do
> their business, and then release it?
> 
> *
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> 
*
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