Response IU

Bill Galloway BillG at
Wed May 15 13:51:11 PDT 2002

* From the T10 Reflector (t10 at, posted by:
* "Bill Galloway" <BillG at>

If this discussion goes as I expect then I will bring in proposals that
clarify that both bits shall never be set at the same time. My initial
proposal will be for SAS but other protocols will be added at the
appropriate time.

I missed the paragraph you cited in SAM while I was researching this
subject. I think I would like to tighten it up a little to change the
"shall only return" to be "shall return" for CHECK CONDITION and "shall
not return" for others.

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at 

-----Original Message-----
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Simpson,
Sent: Wednesday, May 15, 2002 1:57 PM
To: 'T10 Reflector'
Subject: RE: Response IU

* From the T10 Reflector (t10 at, posted by:
* "Simpson, Cris" <cris.simpson at>

> This is a question about FCP, SPI-4, SRP, and SAS Response IU format.
> Is it ever possible for both the RSP_LEN and SNS_LEN bits to be set.

   For SRP, I'm assuming you mean the SNSVALID and RSPVALID bits.  There
is no statement explicitly prohibiting it(^1), but I can see no cases
where you could do so. 

SRP-r15 (6.9) says: 
   Response data shall not be provided in any SRP_RSP response 
   that returns a non-zero status code in the STATUS field.

 But there is no statement of the converse.

> I do not think it is because if RSP_LEN is set then the
> STATUS field is ignored. If the STATUS is ignored then 
> is it even possible to interpret sense data? 

I think not, since if you got RSP data, the command did not complete.

SAM2r23 ( Autosense)
   If supported by the protocol and logical unit and requested by 
   the Execute Command remote procedure call (see 5.1), the device 
   server shall only return sense data in this manner coincident 
   with the completion of a command with a status of CHECK CONDITION.

> I do not know about the response values associated with FCP_DATA (in 
> FCP) but all other responses either prevent the command from being 
> accepted by the target or are task management responses. None of these

> cases have sense data.

> The second question is for what STATUS codes is auto-sense
> data allowed?
> GOOD = ????
> All Others = disallowed.

  See SAM-2 note above.
> What is the answer for GOOD

  Sounds like No.

> and does anyone know of a reason to send sense data for the
> other status codes? 



I would read "shall only return", in the case of CC, to mean "shall

(1) Should SRP explicitly prohibit SNSVALID and RSPVALID from both being


Cris Simpson                                          503.712.4333

Intel EPG/ACD Architecture                           Hillsboro, OR   
PGP Fingerprint:0DA0 418E A27B 0B76 5F02  3DD4 0546 6D13 F88A 1E60

* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at

* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at

More information about the T10 mailing list