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    Re: iSCSI: immediate data



    
    
    Matt,
    
    F is the end of the sequence. If you don't have immediate data but have
    some unsolicited data PDU
    the keep F at 0 until the last unsolicited PDU (presence or absence of
    immediate is indicated by length).
    
    If you have immediate but no other unsolicited or no immediate and no other
    unsolicited F will be 1.
    
    Julo
    
    "Matt Wakeley" <matt_wakeley@agilent.com> on 09-05-2001 19:29:05
    
    Please respond to Matt Wakeley <matt_wakeley@agilent.com>
    
    To:   ips@ece.cmu.edu
    cc:
    Subject:  Re: iSCSI: immediate data
    
    
    
    
    The way I interpret the question is, what if you negotiated immediate data,
    but have no intention on sending immediate data for this command?  Is
    setting
    the F bit, without sending any immediate data valid? (once again, more
    options....)
    
    -Matt
    
    julian_satran@il.ibm.com wrote:
    >
    > 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
    
    
    
    


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Last updated: Tue Sep 04 01:04:44 2001
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