RE: iSCSI: v15 R2T and DATA-OUT

[Paul Koning <ni1d@arrl.net>]

Excerpt of message (sent 24 July 2002) by Rod Harrison:
> 
> 	OK, it's been a long day. Let me try this one more time.
> 
> 	I was write (almost) first time but I meant DATA-OUT instead of
> DATA-IN. Here's what I meant to say ...
> 
> 	There is a potential inconsistency in the description of the use of
> the LUN field in DATA-OUT and R2T in the working v15 draft.
> 
> 	9.7.3 Target Transfer Tag, for DATA-OUT last paragraph says ...
> 
> 	"If the Target Transfer Tag is provided, then the LUN field MUST hold
> a valid value and be consistent with whatever was specified with the
> command;"
> 
> 	9.8.5 Target Transfer Tag, for R2T says ...
> 
> 	"The Target Transfer Tag and LUN are copied in the outgoing data PDUs
> and are used by the target only."
> 
> 	Potentially a target could return a different LUN field in the R2T,
> for perhaps some funky LUN mapping or other internal reason expecting
> it to be copied to the DATA-OUT as per the R2T text.

I think that's a very bad idea and should not be permitted.

If someone wants to do LUN mapping, that's fine, so long as it's
transparent to the initiator.  To map a LUN and then let the mapped
number leak out to the initiator is broken.

> 	I think we need to indicate what is expected of the initiator if the
> LUN field in the R2T does not match the LUN in the command PDU.

Given that the subject was brought up I tend to agree that the spec
should say something.  I would prefer it to say that this is a
protocol error.

	 paul