SCSI-2 Contingent Allegiance handling

Chuck Gibson cgibson at sisa.samsung.com
Wed Sep 27 13:49:00 PDT 1995


What is the proper behavior for a SCSI-2 target when the first command 
received
(from the same initiator) after entering the Contingent Allegiance condition 
is a
tagged command?
The SCSI-2 specification I have (10L) has conflicting information: 
 (uppercase emphasis mine)
In section 7.6 "Contingent allegiance condition", the spec states that
"... The contingent allegiance condition shall be cleared upon .... ANY 
SUBSEQUENT
COMMAND for the I_T_x nexus",  but in section 7.8 "Queued I/O processes", 
the spec states that
"An initiator may not mix the use of tagged and untagged queueing for I/O 
processes to a
logical unit, except during a contingent allegiance or extended contingent 
allegiance
condition, when ONLY UNTAGGED INITIAL CONNECTIONS ARE ALLOWED"
     
After checking a few implementations, there doesn't seem to be a standard 
way to
respond.  In the past, I have cleared CA on the next command from the 
initiator,
regardless of whether it was tagged or untagged.
Any thoughts??

 --------------------------------------------------------------
Chuck Gibson
Samsung Information Systems America  | Phone: (408)232-3613
3655 North First Street                                 | Fax: 
     (408)232-5665
San Jose CA  95134-1713                           | Email: 
cgibson at samsung.com





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