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    Re: iSCSI:Clear Task Set



    John,
    
    That looks more like in  T10 territory.
    T10 defines differently Abort Task Set and Clear Task Set.
    We could either:
    
    decide not to implement clear task set (T10 allows that but "per target" 
    not "per transport")
    enable clear task set - in which case we have to say something about the 
    relative order of the task management request with regard to the  task 
    comming from other initiators - and that is what I attempted to say in 9.4 
    
    
    Julo
    
    
    
    
    
    John Hufferd/San Jose/IBM@IBMUS
    Sent by: owner-ips@ece.cmu.edu
    23-11-01 23:30
    
     
            To:     Julian Satran/Haifa/IBM@IBMIL
            cc:     ips@ece.cmu.edu
            Subject:        Re: iSCSI:Clear Task Set
    
     
    
    
    Julian, and list,
    The question now becomes, if we have all that carefully thought out
    processing that is defined in 9.4 in how to handle the other 
    Tasks/Commands
    that are "In Flight", and not yet given to SCSI, how does that apply to 
    the
    other Sessions with other initiators?
    
    That is, at the iSCSI Target layer we do not have the LU Number to LU
    mapping on any Session with any Initiator, so how do we cause the careful
    processing, which is defined in 9.4, to occur on the other sessions that
    may have and association to the subject LU? Especially since all we know 
    is
    a LU Number on the Clearing Session.
    
    Perhaps we do not care about the 9.4 processing on the other Session and
    Other Initiators and just let SCSI layer do its thing, and at the iSCSI
    layer we pay no attention to the other Sessions.  Do you think this is
    correct?
    
    
    
    
    .
    .
    .
    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
    
    
    Julian Satran/Haifa/IBM@IBMIL@ece.cmu.edu on 11/23/2001 07:56:36 AM
    
    Sent by:  owner-ips@ece.cmu.edu
    
    
    To:   ips@ece.cmu.edu
    cc:
    Subject:  Re: iSCSI:Clear Task Set
    
    
    
    John,
    
    The LUN is just a mistake there - in all three instances it should be LU.
    The definitions are in accordance with SAM . There are two task management
    modes - tasks sets-per-initiator at each LU or common for all initiators.
    The mode is a SCSI issue controlled by a field in the Control-Mode page.
    Clear task set MAY clear all the tasks in the task set - even if common to
    all initiators if that is the way the task set is managed. That is also
    the difference between clear-task-set and abort task set.
    
    Julo
    
    
    
    
    
    
    
    John Hufferd@IBMUS
    23-11-01 11:29
    
    
            To:     Julian Satran/Haifa/IBM@IBMIL@IBMDE
            cc:     ips@ece.cmu.edu
            From:   John Hufferd/San Jose/IBM@IBMUS
            Subject:        iSCSI:Clear Task Set
    
    
    
    Julian, and List  (using v 0.9)
    In point 9.4, just before 9.5  the Table entry associated with Clear Task
    Set applies to:
    
    "All tasks associated with the specified LUN and initiator. For all other
    initiators all tasks at LUN with no regard to order."
    
    Perhaps we mean LU here, but I know that the iSCSI layer does not have
    information about LU, only about the LU Number (LUN) in the command.  We
    can not tell, at the iSCSI layer, if the  LU represented  by a LUN on
    Session 1, has any relationship to any LUN on any other session.
    
    This is because each initiator may have their own numbering for LUs.
    Therefore, do we just pass the Clear Task Set to the SCSI layer and hope
    for the best, or does the iSCSI layer also suppose to apply the Clear Task
    Set to all the sessions that it has coming into the iSCSI (SCSI) Target
    Port?  If the latter, again how will that work when the iSCSI layer has no
    idea what LU an Initiator's LUN will map to?
    .
    .
    .
    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
    
    
    
    
    
    
    
    
    
    
    


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