Review of Persistent Reservation, Problem #3, Reservation key clearing

Bob Snively Bob.Snively at Eng.Sun.COM
Tue Jul 8 15:19:50 PDT 1997


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

PROBLEM #3:

At present, text in 7.13.1.1 says:

	For each initiator that performs a PERSISTENT RESERVE OUT 
	Register service action, the device server shall retain the 
	reservation key until the key is changed by a new PERSISTENT 
	RESERVE OUT command with the Register service action from the 
	same initiator or until the key is reset to the default value 
	of zero by powering down the logical unit, if the last APTPL 
	received by the device server was zero (see 7.13.2) or by 
	performing a Clear, Preempt, or Preempt and Clear service action.
	
Similar text is found in

	7.13.1.3, Release, item a)
	7.13.1.4, Clear, first paragraph
	7.13.1.5, Preempt, 4th paragraph
	7.13.1.6, Preempt and Clear, 7th paragraph
	7.13.2, PERSISTENT RESERVE OUT parameter list, 6th paragraph
	
It is never explicitly indicated what "reset to the default value of zero"
really means.  I believe that it was intended to mean that the 
reservation key is not only set to zero, but unregistered and disassociated
|from any relationship to an initiator port.  That is a necessary behavior
to properly handle the proposed "Write Exclusive, Registrants Only" reservation
type.  If the state of being registered is not cleared by the 
action of resetting the reservation key to the default value of zero, then
an offending initiator cannot be locked out.  In addition, extinct 
initiator tables cannot be recovered, but must remain available for
setting to a non-default value.

FIX?

I suggest that the following changes be installed in the document at
the earliest time allowed by the standardization process.

I suggest that the text be a little more specific in its definition of
resetting the reservation key to the default value of zero, explicitly
indicating that the initiator becomes unregistered and any resources
associated with the initiator be released.  The demonstration paragraph
above (7.13.1.1) would be changed to read:


	For each initiator that performs a PERSISTENT RESERVE OUT 
	Register service action, the device server shall retain the 
	reservation key until the key is changed by a new PERSISTENT 
	RESERVE OUT command with the Register service action from the 
	same initiator or until the initiator registration is removed and the
	key is reset to the default value of zero by one of the following
	actions:
	
	   1)	powering down the logical unit, if the last 
	   	APTPL received by the device server was zero (see 7.13.2) 
	   2)   performing a Clear service action
	   3)	performing a Preempt service action
	   4)   performing a Preempt and Clear service action
	
Similar text indicating that "the initiator registration is removed and the
key is reset to the default value of zero" would be installed in the
following locations:

	7.13.1.3, Release, item a)
	7.13.1.4, Clear, first paragraph
	7.13.1.5, Preempt, 4th paragraph
	7.13.1.6, Preempt and Clear, 7th paragraph
	7.13.2, PERSISTENT RESERVE OUT parameter list, 6th paragraph
	

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