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    Re: iSCSI - Immediate Logout Command PDUs



    
    Matthew,
    
    Logout might be used for several reasons and recovery is one of them (but
    also for maintenance).
    It can also be used to logout a connection different than the one it is
    issued on.
    
    Unlike Login in which the the compelling reason for immediate was avoiding
    deadlocks I do not see the same
    compelling reason to mandate immediate always for logout.
    
    Julo
    
    
    
    "BURBRIDGE,MATTHEW (HP-UnitedKingdom,ex2)" <matthew_burbridge@hp.com>
    @ece.cmu.edu on 17-09-2001 11:54:34
    
    Please respond to "BURBRIDGE,MATTHEW (HP-UnitedKingdom,ex2)"
          <matthew_burbridge@hp.com>
    
    Sent by:  owner-ips@ece.cmu.edu
    
    
    To:   "'ips@ece.cmu.edu'" <ips@ece.cmu.edu>
    cc:
    Subject:  Immediate Logout Command PDUs
    
    
    
    My colleagues and I have been discussing the use of the immediate bit in
    the
    Logout Command PDU.  We came to the conclusion that the immediate bit must
    be set in the Logout Command PDU for the following reasons:-
    
    a) Ordering of the logout PDU provides no benefits.  Ordering allows
    commands received prior to be executed (non-SCSI CDBs) or delivered to the
    SCSI layer (SCSI CDBs).  Even if queued the logout will probably occur
    before those CDBs delivered to the SCSI layer have completed (especially,
    it
    the CDB takes along time to execute such as a long erase!). Also, any
    application worth it's salt will wait for all responses to any commands to
    be received before cleanly terminating an iSCSI session.
    
    b) For recovery, the logout needs to be performed immediately.
    
    c) It keeps the login and logout procedures in sync with each other.
    
    Therefore please can you add to section 2.15 a sub section that reads:-
    
    2.14.x I - Immediate
    Logout MUST be issued as an immediate request (I=1)
    
    Matthew Burbridge
    Senior Development Engineer
    NIS-Bristol
    Hewlett Packard
    Telnet: 312 7010
    E-mail: matthewb@bri.hp.com
    
    
    
    
    


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Last updated: Mon Sep 24 04:17:33 2001
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