Clearing ACA on CHECK CONDITION

Costa Sapuntzakis csapuntz at cisco.com
Thu Jun 1 10:05:51 PDT 2000


* From the T10 Reflector (t10 at t10.org), posted by:
* Costa Sapuntzakis <csapuntz at cisco.com>
*

In Section 5.6.1.1 of the SAM-2 03/27/00, it states that:

If the logical unit accepts a value of one for the NACA bit and
this bit was set to one in the CONTROL Byte of the faulting comand,
then the SCSI-2 rules for clearing a contignent aleegiance condition
shall not apply, In this case, the ACA condition shall only be cleared
by:
....
d) A command with the ACA attribute terminates with a CHECK CONDITION
status

---------------------

Part d) seems dangerous. For example, if during recovery, the initiator 
sends an unsupported CDB and gets CHECK CONDITION, 
ACA is cleared!

This seriously limits the suitability of ACA as a general error-recovery
mechanism.

-Costa

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