Re: iSCSI: Check Condition and Residuals

[Luben Tuikov <luben@splentec.com>]

Black_David@emc.com wrote:
> 
> I think Julian's point is that the use of sense data
> vs. transport support to return residual counts for
> CHECK CONDITION is in T10's domain to specify, and
> we ought to leave it to T10, but warn implementers
> that it would be wrong to assume that iSCSI residuals
> will only show up when GOOD status is returned.

And this is EXACTLY WHAT I'm saying.
Quoting myself here for n-th time:

`` I.e. the target SHOULD NOT look inside the sense data
   and retrieve them [residuals] (EXTENDED COPY exception). ''

This has been an absolute non-issue for me right in
the beginning with this:

Santosh Rao wrote (Thu, 01 Aug 2002 10:11:48 -0700):
> Julian & Robert [Russell],
>
> I raised the same query regarding RESID for FCP/FCP-2 this time last
> year. The response I got for FCP/FCP-2 was that RESID information shall
> be valid, regardless of the scsi status returned. The RESID field, can
> be checked by the scsi transport drivers independent of the SCSI STATUS.
THIS-------------------------------------->^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
> I have enclosed the T10 response from Rob Snivelly below on that issue.
> As per FC-PLDA, the RESID information is valid, regardless of the scsi
> status returned by the device. 
>
> An example of this is the case of "NO SENSE" or "RECOVERED ERROR" check
> condition, when the data transfer may have taken place and a CHECK
> CONDITION is returned. Also, for other CHECK CONDITION status', partial
> data transfer may have taken place and hence, resid information should
> be present.

This alone is CLEARLY implying that targets look up the residuals
right in the sense data, which is totally wrong. (Repeating myself
here again.)

I don't know why this was brought up _at__all_.

The iSCSI document is as clear and complete as anything else
regarding residuals and NOTHING should be touched regarding
that matter. <- that's what I'm saying.

-- 
Luben