(A New) Persistent Reservation Question
Andrew Hisgen
Andrew.Hisgen at Eng.Sun.Com
Fri Oct 27 14:05:52 PDT 2000
* From the T10 Reflector (t10 at t10.org), posted by:
* Andrew Hisgen <Andrew.Hisgen at eng.sun.com>
*
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> From: Roger Cummings <roger.cummings at veritas.com>
> To: "'t10 at t10.org'" <t10 at t10.org>
> Subject: RE: (A New) Persistent Reservation Question
> Date: Fri, 27 Oct 2000 16:30:00 -0400
> MIME-Version: 1.0
> X-Message-Number: 1383
>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Roger Cummings <roger.cummings at veritas.com>
> *
> Gerry,
>
> Thanks for the clarification. In that case, I'd put forward the following
> replacement for the 6th para of 5.5.3.5 which I'd contend is significantly
> clearer (George Penokie helped with this wording in a private thread,
> although I must point out that he doesn't think that the clarification is
> really warranted):
>
> "If the device server receives a PERSISTENT RESERVE OUT command with a
> service action of RESERVE from the Initiator that holds the
> existing reservation, and the Type and Scope in this PERSISTENT RESERVE OUT
> command are identical to the Type and Scope of the existing reservation,
> then the Device Server shall not make any change to the existing reservation
> and shall return a GOOD status."
>
>
> Which leaves me with a clear concern with respect to the situation that I
> identified before. I think it makes no sense to reject a reservation from a
> registered Initiator when that Initiator already has all of the rights to
> the LU that it wants on the basis of an existing Registrants Only
> reservation from some other Initiator.
>
> After all, if you look at Table 9, if another registered Initiator issues a
> release in the presence of an existing reservation, then the existing
> reservation isn't released and a GOOD status is returned. Why then if
> another registered Initiator issues a RO reserve in the presence of an
> existing RO reservation, isn't the existing reservation retained and GOOD
> status returned?
I'ld like to "speak against" what appears to be a proposed change in
the previous two paragraphs. The change is not necessary.
Thanks,
--Andrew Hisgen, PhD
Senior Staff Engineer,
Sun Microsystems
>
> Regards,
>
>
>
>
>
> Roger
>
> -----Original Message-----
> From: Gerry.Houlder at seagate.com [mailto:Gerry.Houlder at seagate.com]
> Sent: Friday, October 27, 2000 3:29 PM
> To: t10 at t10.org
> Subject: Re: (A New) Persistent Reservation Question
>
>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Gerry.Houlder at seagate.com
> *
>
> Roger asked:
>
> >Is the 6th paragraph of 5.5.3.5 intended to refer ONLY to a second reserve
> >that is IDENTICAL in type, scope and source (initiator) to an existing
> >reservation ??
>
> My answer: Yes it is.
>
> You are correct that other initiators can inherit access from a registrants
> only reservation, but they cannot become the owner of that reservation
> unless the original owner (initiator) releases his reservation. This is a
> feature, not a bug. The difference is response you have noted is an easy
> way to tell whether you are the owner of the reservation or if another
> initiator is.
>
>
>
>
>
> Roger Cummings <roger.cummings at veritas.com>@t10.org on 10/27/2000 10:49:23
> AM
>
> Sent by: owner-t10 at t10.org
>
>
> To: "'t10 at t10.org'" <t10 at t10.org>
> cc:
>
> Subject: (A New) Persistent Reservation Question
>
>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Roger Cummings <roger.cummings at veritas.com>
> *
> Folks,
>
> I have a question about the definition of Persistent Reservations in SPC-2
> that I don't believe is covered by anything currently in 00-267r2. The
> question is related to the following:
>
> The 6th paragraph of 5.5.3.5 (with the response to Quantum #402 included)
> says:
>
> "If the device server receives a PERSISTENT RESERVE OUT command with a
> service action of RESERVE where
> the TYPE and SCOPE are the same as the existing TYPE and SCOPE from the
> initiator that created the persistent reservation,
> it shall not make any change to the existing reservation and shall return a
> GOOD status."
>
> I'm not sure that I can parse this sentence correctly, but at face value it
> appears to conflict with Table 9, where any Reserve command received where
> the addressed LU has a reservation from a different initiator gets a
> conflict.
>
> Is the 6th paragraph of 5.5.3.5 intended to refer ONLY to a second reserve
> that is IDENTICAL in type, scope and source (initiator) to an existing
> reservation ??
>
> What I'm worried about is this situation:
>
> 1) There's an existing Registrants Only (RO) LU reservation to LU 1 from
> registered Initiator A.
> 2) An identical RO LU reservation to LU 1 is received from Registered
> Initiator B.
>
> can the reservation in 2) get a Good (allowed) response, per 5.5.3.5 ???
>
> Note the prior reservation doesn't need to change to grant B access
> [because
> the reservation in 1) allows Initiator B full access anyway].
>
> To look at this from another way, does it really make sense that the
> reservation in 2) above gets a conflict when just about any other command
> that Registered Initiator B sends will be allowed ?? Surely it would be
> better, in the case where the rights granted under the new reservation
> would
> be IDENTICAL to the existing reservation, to allow the command and not
> change the existing reservation (i.e. make the response allowed in the 3rd
> column of table 9 and have a note similar to the one for Release).
>
> Regards,
>
>
>
>
>
>
>
> Roger Cummings
> VERITAS Software
>
> roger.cummings at veritas.com
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