Proposed Changes to Persistent Reservation

John Meneghini USG johnm at zk3.dec.com
Thu Apr 29 14:47:21 PDT 1999


* From the T10 Reflector (t10 at symbios.com), posted by:
* John Meneghini USG <johnm at zk3.dec.com>
*
Bob,

Thanks so much for your suggestions.

Please see my comments below.

/John

-----------------------------------------------------------------------------
> (on Thu, 29 Apr 1999 10:31:11 -0700 (PDT) ):
> Bob Snively <Bob.Snively at Ebay.Sun.COM> wrote:
> * From the T10 Reflector (t10 at symbios.com), posted by:
> * Bob Snively <Bob.Snively at Ebay.Sun.COM>
> *
> Tom,
> 

[...]

> Approaching the most significant question, item I, I believe your
> argument in favor of the status quo is flawless:
> 
> 	"The argument in favor of the status quo is presumably based
>        on a desire to protect the logical unit from an initiator
>        that is not participating in the proper key assignment algorithm."
>
> This is exactly the type of security that is intended by Persistent
> Reservation.  

Agreed.

Perhaps a more accurate way of stating the the problem with the status
quo argument is: it not only protects the logical unit from other
initiators not holding the Reservation, but it prevents the Initiator
who holds the Reservation from easily managing the it.

> If you don't have the magic key, you are forced to
> perform a special dance, involving either questioning the other
> hosts that share your device about their activities and how they may
> relate to those you would like to perform, or alternatively
> destroying all their activities through an appropriate series of
> self-preemptions followed by subsequent preemptions.  

I believe the scenario you've described here contains several tacit
but very powerful assumptions.  Assumptions about what the abilities
of the Application Client are and about how, exactly, the Application
Client will implement and use Persistent Reservations.  

Is the Application Client assumed to be always: a) distributed and b)
monolithic in its nature ?

Also, could you please explain more about what you mean by: "an
appropriate series of self-preemptions followed by subsequent
preemptions" ?

Thanks,

---
John Meneghini             Contracted to Compaq                  
johnm at zk3.dec.com




*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at symbios.com





More information about the T10 mailing list