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    RE: iSCSI: FirstBurstSize and unsolicited data



    The specifications says
     If you send any non-immediate unsolicited data-out PDUs, the total
    unsolicited amount of data should be FirstBurstSize amount of data.
    
    
    Regards
    Sanjay Goyal
    
    
    -----Original Message-----
    From: Nandakumar Ramamurthy [mailto:nramamur@npd.hcltech.com]
    Sent: Friday, June 14, 2002 7:16 AM
    To: ips@ece.cmu.edu
    Subject: iSCSI: FirstBurstSize and unsolicited data
    
    
    Hi All,
    
    Consider the case where InitialR2T=yes and ImmediateData=yes.
    All other values are the defaults.
    
    The expected data transfer length for a SCSI write
    operation is a value exceeding FirstBurstSize (64KB).
    
    In the above case, the initiator will send immediate
    unsolicited data (MaxRecvPDULength=8192 bytes).
    After that it has to wait for an R2T from the target.
    
    In this scenario, FirstBurstSize of data will not be sent
    to the target as unsolicited data-out's cannot be sent here.
    
    My understanding is that the remaining data can be
    sent only through solicited Data-out PDUs,
    and this is the expected way according to the draft.
    
    What does the following statement(in Section 9.4.6.2 Sense Data) mean in
    this context ?
    
    <quote>
    
    The target reports the "Not enough unsolicited data" condition only
    if it does not support output (write) operations in which the total
    
    data length is greater than FirstBurstSize, but the initiator sent
    
    less than FirstBurstSize amount of unsolicited data, and out-of-order
    
    R2Ts cannot be used.
    
    </quote>
    
    If this is specific to the SCSI layer at the target,
    what is the dependency on FirstBurstSize?
    
    Please clarify.
    
    Thanks,
    Nandakumar
    Member Technical Staff
    HCL Technologies, Chennai, INDIA.
    http://san.hcltech.com
    
    


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Last updated: Fri Jun 14 14:18:43 2002
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