SAM-2 status precedence - RESERVATION CONFLICT vs. CHECK CONDITON/UNIT ATTENTION/POWER ON OCCURRED

[Elliott, Robert]

* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert" <Robert.Elliott at COMPAQ.com>
*
SAM-2 requires that RESERVATION CONFLICT status always have priority 
over CHECK CONDITION status:

"5.3.2 Status precedence
 If more than one condition applies to a completed task, the report
 of a BUSY, RESERVATION CONFLICT, ACA ACTIVE or TASK SET FULL 
 status shall take precedence over the return of any other status 
 for that task."

However, after power up, most targets with a persistent reservation 
stored in non-volatile memory return CHECK CONDITION status to report 
a unit attention with an additional sense code of POWER ON OCCURRED 
rather than report the RESERVATION CONFLICT status.

Depending on how you interpret "more than one condition applies"
this violates the SAM-2 precedence rule.

Also, SPC-3 describes how CHECK CONDITION/NOT READY is supposed 
to be returned after power on until the persistent reservation 
information has been loaded.

How should the SAM-2 text change to fix this?
a) change "shall" to "should"
b) add "except for a CHECK CONDITION status reporting a 
UNIT ATTENTION sense key with an additional sense code with
an ASC set to 29h, or a CHECK CONDITION status reporting
a NOT READY sense key"
c) other suggestions

---
Rob Elliott, Compaq? Server Storage
Robert.Elliott at compaq.com


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