iSCSI: Task Management

["Prasenjit Sarkar/Almaden/IBM" <psarkar@almaden.ibm.com>]

I dont know whether this has been raised before.

With reference to the Task Management section of the document, it is my
opinion
that the target reset function from an initiator should be limited to the
LUNS
exposed to that initiator, and the connections to only that initiator be
closed.
The motivation is that an initiator with access to a single LUN should not
be
able to bring down an entire target device with 1000s of LUs. From my
experience,
there are enough buggy initiators which can generate target resets at the
first chance.

Implementors may control Target Reset behavior with Jim Hafner's access
control
stuff in T10.

Sincerely,
Prasenjit


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<!--StartFragment-->3.7.1.  Function

     The Task Management functions provide an initiator with a way to
     explicitly control the execution of one or more Tasks. The Task
     Management functions are summarized as follows (for a more detailed
     description see the [SAM2] document):
          1    Abort Task---aborts the task identified by the Referenced
               Task Tag field.
          2    Abort Task Set---aborts all Tasks issued by this initia-
               tor on the Logical Unit.
          3    Clear ACA---clears the Auto Contingent Allegiance condi-
               tion.
          4    Clear Task Set---Aborts all Tasks (from all initiators)
               for the Logical Unit.
          5    Logical Unit Reset.
          6    Target Reset.
     For the functions above except <Target Reset>, a SCSI Task Manage-
     ment Response is returned, using the Initiator Task Tag to identify
     the operation for which it is responding.  For the <Target Reset>



Satran, Smith, Sapuntzakis, Meth                               [Page 23]

iSCSI                         June 2000


     function, the target cancels all pending operations. The target may
     send an Asynchronous Event to all attached initiators notifying
     them that the target is being reset.  The target then closes all of
     its TCP connections to all initiators (all sessions are ter-
     minated).


<!--EndFragment-->





   Prasenjit Sarkar
   Research Staff Member
   IBM Almaden Research
   San Jose