Re: ISCSI: Immediate data extending beyond a single PDU

[julian_satran@il.ibm.com]

Pierre,

I am not sure I see where the problem is.

Both today and with Barry's suggested addition you can send EITHER
immediate or a regular unsolicited burst. In case you choose to do the
later the end is marked by the F bit. In case you choose immediate it is
only 1 PDU.  Expected Data Length is for the whole operation (not only the
first burst).

Barry suggested that we restrict also, at target choice, the type of
unsolicited data to immediate
(we either let UseR2T:yes and ImmediateData:yes mean only immediate data or
better UseR2T:no ImmediateData:ONLY) for the convenience of some targets.

In all the cases the target knows when the FirstBurst is over (now and with
Barry's proposed change).

Am I missing something?

Regards,
Julo



Pierre Labat <pierre_labat@hp.com> on 07/02/2001 20:56:57

Please respond to Pierre Labat <pierre_labat@hp.com>

To:   ips@ece.cmu.edu
cc:
Subject:  Re: ISCSI: Immediate data extending beyond a single PDU




julian_satran@il.ibm.com wrote:

> Barry,
>
> I think that the current draft does not allow you to accept immediate but
> not unsolicited.
> You can either allow unsolicited (including immediate) or request always
> R2T.
>
> And yes - if the expected length is larger that what you sent as
> unsolicited (even if the unsolicited was less than the limit) the target
is
> supposed to send R2T (there is only one unsolicited burst per command).

Julian, Barry,

I think there is a problem, as stated Barry, if the initiator decides to
send unsolicited data but less than the Firstburst and
the expected length is greater than the Firstburst. In this case the
initiator

after sending some unsolicited data waits for an R2T to continue
and the target waits for a First burst load of data before sending
an R2T.

Solution
======
To avoid that, it should be explicitely stated (may be it's what
is assumed but i can't read it) that when the initiator sends
unsolicited non immediate data, it must send unsolicited data
up to Firstburst or Expected data length whichever is less.

Regards,

Pierre

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