Question on 9.2.6.3.3.6 ST_TTS5:Receive_Data_Out state in sas1r06

Elliott, Robert (Server Storage) elliott at hp.com
Fri Nov 19 17:39:35 PST 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:
> * "Chang, Neil" <neil.chang at intel.com>
> *
> Specification described the following:
> -----
> 9.2.6.3.3.6 ST_TTS5:Receive_Data_Out state
> 9.2.6.3.3.6.1 State description
> If this state receives a Data-Out Arrived message from the 
> ST_TFR state
> machine, then this state shall verify the DATA frame received with the
> message as follows:
> 1) check the data offset. If the data offset was not expected 
> (i.e., the
> CHANGING DATA POINTER bit is set to one and the value in the 
> DATA OFFSET
> field is not set to a data offset associated with a previous ACK/NAK
> balance, or the CHANGING DATA POINTER bit is set to zero and the value
> in the DATA OFFSET field is not set to the value in the DATA OFFSET
> FIELD in the previous DATA information unit plus the number 
> of bytes in
> that information unit), then this state shall send a 
> Reception Complete
> (Data Offset Error) message to the ST_TFR state machine;
> -----
> The question:
> When target receives the data and the CHANGING DATA POINTER bit is set
> to one, shouldn't the target expect the data offset to be the previous
> XFER_RDY offside, as described in section 9.2.4.5.2 DATA frame with
> transport layer retries?

Yes, that was the intent.  Retries of write DATA frames are supposed to
go back to the XFER_RDY point.  Retries of read DATA frames go back to
an ACK/NAK balance point.  There are several errors in ST_ITS and ST_TTS
concerning this, which will be corrected in sas-r07.

> 
> Thanks,
> Neil Chang

--
Rob Elliott, elliott at hp.com
Hewlett-Packard Industry Standard Server Storage Advanced Technology
https://ecardfile.com/id/RobElliott


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