Persistent Reserve register action with common reservation key

Tom Coughlan coughlan at star.zko.dec.com
Mon Jan 5 06:23:59 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* coughlan at star.zko.dec.com (Tom Coughlan)
*
In the attached mail, Gerry writes:

>Persistent reservations have been expanded to explicitly allow different
>initiators to register the same reservation key. This has the effect of
>allowing one initiator to get the same access rights as another initiator.

This is not the way Persistent Reservations are intended to work.  The
access rights of an initiator are determined by the initiator's
transport-specific identifier, not the reservation key.  

This was discussed and agreed upon at the SCSI Working Group in May
1997 (Natick), in preparation for the change to allow non-unique keys.  

I agree that this should be stated more explicitly in the Standard.  At the
moment, the most explicit statements of the requirement are in the table
that described the reservation Type Codes, where it defines the behavior in
terms of "the initiator holding the reservation", not "the initiators with
a key that matches that of the reservation".

Tom

From:	US2RMC::"Gerry_Houlder at notes.seagate.com" "MAIL-11 Daemon" 24-DEC-1997 18:29:14.29
To:	t10 at Symbios.COM
CC:	
Subj:	Persistent Reserve register action with common reservation key

* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* Gerry_Houlder at notes.seagate.com
*
Persistent reservations have been expanded to explicitly allow different
initiators to register the same reservation key. This has the effect of
allowing one initiator to get the same access rights as another initiator.
What should happen when one of the initiators registers a new reservation
key when there is an active reservation for that key?

The existing document wording says that the reservation transfers to the
new key, but this leaves the other initiator that thought it had an active
reservation with RESERVATION CONFLICT. Should this really be allowed?

It also brings up the point of whether an initiator that doesn't have any
reservation should be allowed to register a new reservation key that is the
same as a key that has an active reservation. This effectively allows
anyone to become the reservation owner whenever they want to. Should this
be allowed?

Perhaps the "register" service action should be changed to:
(a) not permit a new initiator to register with a key that currently has an
active reservation,
(b) if an initiator has an active reservation and changes its reservation
key, the reservation doesn't transfer to the new key if another initiator
is registered with the same key.


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