Re: iSCSI: immediate data

[julian_satran@il.ibm.com]

That is correct. The final bit indicates the end of unsolicited  data.
If all you have is immediate then the final bit is 1in the command.
If you have immediate and other unsolicited (if enabled!) then set F to 0.

2.3.1 has been fixed accordingly.

Regards,
Julo

sandeepj@research.bell-labs.com (Sandeep Joshi) on 09-05-2001 01:56:25

Please respond to sandeepj@research.bell-labs.com (Sandeep Joshi)

To:   matt_wakeley@agilent.com
cc:   ips@ece.cmu.edu
Subject:  Re: iSCSI: immediate data




Umm.....Julian replied to this one and said the final bit on ScsiCmd
would indicate it.   Apparently, a single command can now send
the unsolicited data both with the command and in separate PDUs.

I cant seem to find the email but I believe Sec 2.3.1 was changed
accordingly.  Julian..?

-Sandeep

> The intention is that if an initiator requests to send immediate data
(and is
> granted the request), then it will always send immediate data.
>
> It sounds like you are asking for wishy washy mode... sometimes send
immediate
> data, sometimes not.
>
> -Matt
>
> Sandeep Joshi wrote:
> >
> > Julian,
> >
> > I had a follow-up question on an old thread.
> >   http://ips.pdl.cs.cmu.edu/mail/msg03373.html
> >
> > The initiator is allowed to send firstburst in immediate
> > or in separate PDUs...but can it do neither ?  I dont
> > see any statement to the effect that it MUST send a
> > firstburst.
> >
> > Here's a possible problem :
> > 1) FirstBurst is 4K
> > 2) Expected data length of command is 16K
> > 3) Initiator sends the Scsi command without immediate
> >    data.   (final flag on Scsi command is not set)
> >    And it decides to send no further data PDUs.
> >
> > The target does not know if R2Ts can be sent since it does
> > not know if any unsolicited PDUs are expected.
> >
> > Perhaps the semantics on the final flag on SCSI command
> > need to be changed to indicate that no unsolicited data
> > will be sent with this command.  Currently, the flag implies
> > (Sec 2.3.1) that all the required data has been sent with
> > the command.
> >
> > And here's a typo to fix.  Appendix E (Key=immediateData)
> > The following should say "initialR2T is no".
> > The table has got it right.
> >
> > > If ImmediateData is set to yes and InitialR2T is set
> > > to yes then the initiator MAY send unsolicited immediate
> > > data or one unsolicited burst of Data-OUT PDUs but
> > > MUST NOT send both immediate and a unsolicited burst of
> > > Data-OUT PDUs for any one command.
> >
> > -Sandeep