SORT BY:

LIST ORDER
THREAD
AUTHOR
SUBJECT


SEARCH

IPS HOME


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

    RE: iSCSI: padding on intermediate sequences



    It is the sequences I am speaking of, not the segments. The current wording
    of the spec would allow you to send sequences with padding in each sequence
    (the segments within the sequence are ok because they can't have padding).
    But if a transfer is made up of several sequences then it is more work for
    the hardware if intermediate sequences were allowed to have arbitrary pad
    bytes.
    
    And there is no good reason (that I am aware of) that intermediate sequences
    could not just be pure data.
    
    Now, if there is a reason, then we should come up with a scheme that allows
    one party to "just say no". One possibility is that if DataInOrder=yes, then
    padding would not be allowed except in the sequence that represents the last
    portion of the transfer. 
    
    If that is objectionable, then we should have a new key
    (PaddingOnlyInLastSequenceOfTotalTransfer=yes). :-)
    
    Eddy
    
    -----Original Message-----
    From: Robert D. Russell [mailto:rdr@io.iol.unh.edu]
    Sent: Tuesday, March 26, 2002 2:48 PM
    To: Eddy Quicksall
    Cc: ips@ece. cmu. edu (E-mail)
    Subject: Re: iSCSI: padding on intermediate sequences
    
    
    Eddy:
    
    I may not be understanding you correctly, but the
    words in section 9.7.7 I believe mean that these data
    segments should contain an integer number of 4 byte words
    of data, not arbitrary "pad" bytes.  If the data segment
    length is a multiple of 4 then there will be NO pad bytes.
    
    There seems to be confusion over your use of "pad"
    and the standard's use of "pad".  Would you please clarify?
    
    Thanks,
    Bob
    
    
    On Tue, 26 Mar 2002, Eddy Quicksall wrote:
    
    > Section 9.7.7 says:
    >
    > The Data Segments of Data-in and Data-out PDUs SHOULD be filled to the
    > integer number of 4 byte words (real payload) unless the F bit is set
    > to 1.
    >
    > This allows one to pad intermediate sequences of a transfer. But, there
    are
    > reasons why padding on intermediate sequences within a transfer can make
    > life difficult.
    >
    > Can we forbid padding on all but the last PDU for the transfer? If that is
    > objectionable, could we forbid padding on all but the last PDU of a
    transfer
    > if DataInOrder=yes.
    >
    > Eddy
    >
    


Home

Last updated: Wed Mar 27 03:18:38 2002
9334 messages in chronological order