Response IU

Simpson, Cris cris.simpson at
Wed May 15 11:56:58 PDT 2002

* 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 return".

(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

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