Re: iSCSI : On the subject of R2T and Task Tags.

[Santosh Rao <santoshr@cup.hp.com>]

Matt Wakeley wrote:

> The task tags in iSCSI should work the same as they do in FCP:
>
> The target supplies a target task tag per task that it sends to the initiator
> where a response from the initiator is expected.  The target uses the target
> task tag to associate any solicited received messages from the initiator
> (other than the initial command) to that task.
>
> For SCSI WRITE commands, the target MAY assign a target task tag to the I/O
> that it uses when sending R2Ts to the initiator.  The initiator must then echo
> that target task tag in replies it sends to the target.  I strongly object to
> the words in section 2.16 "All outstanding R2T should have different Target
> Transfer Tags".  This specification should not dictate to the target how it
> chooses or uses the Target Task Tags.
>

I agree with Matt on the semantics of "Target Task Tag" for WRITE PDUs and would
also like to request a "Target Task Tag" per task for WRITE PDUs.

In addition, since multiple R2Ts can be outstanding, an additional qualifier is
required to track the R2T (Target R2T Tag) along the lines of a (RX_ID + SEQ_ID)
that Fibre Channel uses.

Thanks,
Santosh
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