Write buffer command

Elliott, Robert (Server Storage) elliott at hp.com
Mon Oct 25 12:33:18 PDT 2004

* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <elliott at hp.com>

> * From the T10 Reflector (t10 at t10.org), posted by:
> * Burn Alting <burn at goldweb.com.au>
> *
> I believe there is one thing missing from the Write Buffer 
> command when saving microcode - what if the save fails? 

SPC-3 6.33.8 prohibits GOOD status in the case of any errors
in the image, and general SCSI definition of GOOD status
means the command did what was requested, so CHECK CONDITION 
status should be returned if there is an error:

"when the logical unit detects the last ... WRITE BUFFER command,
... the device server shall perform any logical unit required
verification of the complete set of downloaded microcode or
control information prior to returning GOOD status."

> What sort of check condition should be offered and what about the 
> additional sense key qualifiers?
> Basically, how do we tell the initiator that the save failed and
> there could be problems on the next hard reset?

The sense key could be ILLEGAL REQUEST or HARWARE ERROR depending on the
nature of the problem.  ILLEGAL REQUEST is used when there is something
wrong in the image being sent.  HARDWARE ERROR would imply a major
failure (e.g. the ROM is now corrupted).

There are no standardized additional sense codes to pinpoint the reason
for the failure - a vendor-specific value (80h+) might even be used.

Rob Elliott, elliott at hp.com
Hewlett-Packard Industry Standard Server Storage Advanced Technology

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