RE: iSCSI: Data In PDU with S bit set

[pat_thaler@agilent.com]

Title: RE: iSCSI: Data In PDU with S bit set

Dennis,

 

You appear to have misunderstood the question. Lakshmi wasn't asking about whether a separate SCSI Response PDU could be used instead of setting the S bit. The question was about whether a SCSI Response PDU could be sent fora a command when the S bit had been set in the Data-In PDU.

 

See Eddy's response. Sending the status completes the task. It doesn't matter whether the status was sent with phase collapse by setting the S bit in a Data-In PDU or with separate SCSI Response PDU. iSCSI doesn't need to add anything about this. Processing status belongs to SAM.

 

Pat

 

-----Original Message-----
From: Dennis Young [mailto:DYoung@Brocade.COM]
Sent: Wednesday, February 19, 2003 6:48 PM
To: 'Buck Landry'; Lakshmi Ramasubramanian
Cc: ips@ece.cmu.edu
Subject: RE: iSCSI: Data In PDU with S bit set

In section 10.7 (draft 20):

   Status can accompany the last Data-in PDU if the command did not end
   with an exception (i.e., the status is "good status" - GOOD,
   CONDITION MET or INTERMEDIATE CONDITION MET).  The presence of
   status (and of a residual count) is signaled though the S flag bit.
   Although targets MAY choose to send even non-exception status in
   separate responses, initiators MUST support non-exception status in
   Data-In PDUs.

Based on the last sentence of the above paragraph, the initiator has
to be able to handle both cases, while the target has the option to
not send a separate response if there is no exception.

-Dennis

>-----Original Message-----
>From: Buck Landry [mailto:blandry@crossroads.com]
>Sent: Wednesday, February 19, 2003 5:18 PM
>To: Lakshmi Ramasubramanian
>Cc: ips@ece.cmu.edu; Julian_Satran@il.ibm.com
>Subject: RE: iSCSI: Data In PDU with S bit set
>
>
>Well, I don't see any explicit text (too bad), but..
>
>3.5.1.5 "the last SCSI Data-in PDU passed for a command may
>also contain the status if the status indicates termination
>with no exceptions (no sense or response involved)"
>
>.. implies (maybe just to me) that the SCSI task is terminated
>by a Data-In PDU w/S bit set.  A further response to a
>terminated task would be inappropriate methinks, unless you
>want to start talking about error recovery..
>
>Hope this helps, --buck
>
> -----Original Message-----
>From: Lakshmi Ramasubramanian [mailto:nramas@windows.microsoft.com]
>Sent: Wednesday, February 19, 2003 4:55 PM
>To: ips@ece.cmu.edu
>Subject: iSCSI: Data In PDU with S bit set
>
>
>If the target sends a Data In PDU with S bit set,
>can it also send a SCSI Response PDU for the same command?
>
>If the answer is no, there is no text in the spec that
>says a target should not send scsi response PDU.
>
>thanks!
> -lakshmi
>
>
>
>
>