Persistent Reserve register action with common reservation key

Bob Snively Bob.Snively at Eng.Sun.COM
Fri Jan 16 13:31:10 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* Bob Snively <Bob.Snively at Eng.Sun.COM>
*

Gerry,

The use of the same reservation key by two different initiators does
not give two initiators the same access rights.  Access rights are
established by execution of a P R OUT command from a particular initiator ID
and apply to that initiator only (except for the special case of
registrant related reservations).  When a command is executed, only
the reserving initiator gets whatever special rights are granted (again
noting the same special case).  All other initiators, regardless of
reservation key, have the rights that were assigned to them by the
reserving initiator, and no more.

However, when a preempt and clear is performed, it is the reservation key
that indicates which reservations are to be cleared (assuming they also
match in scope and type).  As a result, the granting of the
same reservation key to two initiators does not grant them any shared
reservation power, but does allow them to both have their reservations
cleared with a single preempt and clear.

Hope that clarifies what I believe was intended.  I believe it matches with
Tom's earlier response to you.

Bob

> X-Lotus-FromDomain: SEAGATE at INTERNET
> To: t10 at Symbios.COM
> Date: Wed, 24 Dec 1997 16:59:47 -0600
> Subject: Persistent Reserve register action with common reservation key
> Mime-Version: 1.0
> 
> * 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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