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    Re: Task management questions



    
    I think Gwendal has a point.  This and section 9.4 are very hard sections
    to read and understand.  Perhaps we did not mean all that is said here.
    
    In addition too, or in support of Gwendal, I also found that the paragraph
    that begins  "For all these Functions..." in 3.5.1 needs to be Harmonized
    with the "Abort Task Must..." Paragraph since they are clearly at odds,
    especially since the Abort Task is one of the functions addressed in the
    previous paragraph.  But I simply do not understand how the following
    statement:
    
    "...the target MUST deliver to the initiator good status for all aborted
    task for which no status was delivered yet. The task management response
    MAY be issued by the target immediately after marking all tasks to be
    aborted."
    
    can be made to work with section 9.4 which goes to great pain to "silently
    discard" commands that are covered by the Abort but have not yet been
    executed.  (See the last item b on  page 156.)  I think silently discard
    means do not return Status.
    
    After we sort out the above, we still have to deal with the differences
    right within  9.4.  That is the first item d on page 156 states:
    
    "Note: Any entries that had been marked as a candidate for cleanup have now
    been delivered by the target to its SCSI layer. The SCSI layer will have to
    determine if they are to be aborted."
    
    and the last item b states:
    
    "remove the oldest barrier list item and evaluate all queued entries that
    have a CmdSN field less than ExpCmdSN, removing and silently discarding
    each queued command that meets the criteria for cleanup candidacy (as
    specified by the task management function)"
    
    This means DO NOT SEND THEM TO SCSI !   Therefore, they had not been
    delivered by the target to its SCSI layer as stated above.
    
    So we have one place saying that SCSI layer will determine, and the other
    place finding a method not to send them to SCSI.
    
    I understand what is being attempted here (to meet the requirements of
    SAM-2 (1157-D) section 5.5.2 that states "... no notification that the
    task(s) have been aborted shall be returned to the initiator...."  however,
    our documentation needs some clean-up to make it consistent.
    
    This is NOT a  change to the protocol, just a clean up of our
    documentation, but the way it is now it is hard to perform the protocol and
    follow the documentation in this specific area.
    
    
    
    .
    .
    .
    John L. Hufferd
    Senior Technical Staff Member (STSM)
    IBM/SSG San Jose Ca
    Main Office (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
    Home Office (408) 997-6136, Cell: (408) 499-9702
    Internet address: hufferd@us.ibm.com
    
    
    Gwendal Grignou <ggrignou@silverbacksystems.com>@ece.cmu.edu on 11/23/2001
    02:03:02 PM
    
    Sent by:  owner-ips@ece.cmu.edu
    
    
    To:   "ips" <ips@ece.cmu.edu>
    cc:
    Subject:  Task management questions
    
    
    
    I have a question about the section 3.5.1 page 69.
    The paragrah starting with "ABORT TASK MUST",the last sentene says "The
    task
    management response MUST be issued after the command status (if any) was
    issued." : it means the initiator will receive, on the same connection, a
    status for the aborted task and AFTER, a response for the task management
    function.
    
    In the paragraph before (starting with "For all these functions,",), it is
    specified that the target should send a status for all aborted tasks, but
    the
    task management response can happen at any time after the task management
    request has been received by the target "The task management response MAY
    be
    issued by the target immediately after marking all tasks to be aborted."
    
    Why such a difference between "ABORT TASK" function and other functions ?
    
    About, "LOGICAL UNIT RESET", it is stated "the target MUST behave as
    dictated
    by the Logical Unit Reset function in [SAM2]." However, in SAM2, taks
    should
    be aborted as described in section 5.6 of SAM2, which says , in section
    5.6.2, about initiator aborting their own task "When an initiator causes
    its
    own task(s) to be aborted, no notification that the task(s) have been
    aborted
    shall be returned to the initiator other than the completion response for
    the
    command or task management function action that caused the task(s) to be
    aborted and notification(s) associated with related effects of the action
    (e.g., a target reset unit attention condition)." Does it means the iSCSI
    target may not send a status for the aborted tasks in case of a
    "LOGICAL UNIT RESET" ? (and subsequently for TARGET RESET [WARM or COLD]
    which triggers LOGICAL UNIT RESET for each LUs [SAM2, section 5.8.6]). It
    does not match with the requirement in the paragraph concerning all the
    task
    management functions in general.
    
    Can you elaborate more on those requirements ?
    
    Thanks a lot,
    
    Gwendal.
    
    
    
    
    


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