SORT BY:

LIST ORDER
THREAD
AUTHOR
SUBJECT


SEARCH

IPS HOME


    [Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

    RE: iSCSI: changing MaxPDUDataLength



    Julian,
     
    Another problem here is that the target has to calculate the offset from the DataSN #. And as BegRun can be any value. E.g., BegRun=4 and RunLngth=0 means starting DataSN=4, send all the data for that sequence.
     
    I think it would be a performance hit and waist of memory to keep a tally of all PDU sizes just for an occasional SNACK.
     
    It's not that it can't be done ... it is more that it is messy and I think there is a solution that will satisfy the design requirements but keep the software simpler.
     
    Eddy
    -----Original Message-----
    From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
    Sent: Saturday, June 08, 2002 10:16 PM
    To: Eddy Quicksall
    Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu; pat_thaler@agilent.com
    Subject: RE: iSCSI: changing MaxPDUDataLength


    That is not completely accurate.
    The only problem is when PDU size decreases and then SNACK must be for all data.
    Target can also keep a mapping of numbers/to offsets (the list should be small and if it gets long ask for ack (A-bit).

    Julo


    Eddy Quicksall <eddy_quicksall@ivivity.com>
    Sent by: owner-ips@ece.cmu.edu

    06/08/2002 10:54 PM
    Please respond to Eddy Quicksall

           
            To:        pat_thaler@agilent.com
            cc:        ips@ece.cmu.edu
            Subject:        RE: iSCSI: changing MaxPDUDataLength

           


    Thanks,

    As a target, I won't be able to let it change until all of the outstanding
    commands are finished (running with ErrorRecoveryLevel>=1). This is because
    I must use the PDU size to compute the offset from a SNACK's
    BegRun/RunLength.

    So, I plan to not give the text response for a MaxPDURecvDataLength in FFP
    until I get back an ExpStatSN == next StatSN.

    This will cause a delay of unknown time before the PDU size can actually
    change ... do you see any problem with this?

    Eddy

    -----Original Message-----
    From: pat_thaler@agilent.com [mailto:pat_thaler@agilent.com]
    Sent: Friday, June 07, 2002 1:13 PM
    To: eddy_quicksall@ivivity.com; ips@ece.cmu.edu
    Subject: RE: iSCSI: changing MaxPDUDataLength


    Eddy,

    If one uses a message sync and steering that relys on the transport segments
    carrying a full PDU, e.g. TCP ULP Framing Protocol (TUF), then if the path
    MTU changes one would want to change the PDU data length to fit the new path
    MTU.

    Pat

    -----Original Message-----
    From: Eddy Quicksall [mailto:eddy_quicksall@ivivity.com]
    Sent: Wednesday, June 05, 2002 12:24 PM
    To: ips@ece.cmu.edu
    Subject: iSCSI: changing MaxPDUDataLength


    Does anybody know a case where it is necessary to support a new PDU data
    length during full feature phase?

    Eddy
    mailto: Eddy_Quicksall@iVivity.com





Home

Last updated: Mon Jun 10 20:18:49 2002
10648 messages in chronological order