RE: Several iSCSI protocol questions

[Black_David@emc.com]

> > > Since the Task Management Function itself has a CmdSN and
> > > valid LUN, can one
> > > Task Management Function affect (abort) another?
> >
> > No, SCSI task management functions operate on *SCSI* tasks, not *iSCSI*
> > tasks, and a task management function is not a *SCSI* task - see SAM-2.
> 
> This contradicts the text in Section 9.5.1: "The Task Management functions
> provide an initiator with a way to explicitly control the execution of one
> or more Tasks (SCSI and iSCSI tasks)."  Your interpretation makes more
sense
> to me, however.

And there's more text further down in 9.5.1 that seems to imply that
one ought to be able to abort a Task Management Function.

  All these functions apply to the referenced tasks regard-
  less of whether they are proper SCSI tasks or tagged iSCSI opera-
  tions.

I think you've caught something we need to fix ...

> > > If not, then what is the
> > > appropriate Task Management Function Response for an ABORT TASK that
> > > attempts to operate on another Task Management Function?
> >
> > That can't happen.  The only task management function that could
possibly
> > attempt "to operate on another Task Management Function" is ABORT TASK,
but
> > it identifies the task to be aborted by an Initiator Task Tag, something
> > that Task Management Functions *do not* have - see Section
> > 9.5 of the iSCSI draft.
> 
> I am looking at Section 9.5.  I see "Initiator Task Tag" in the table
> showing the PDU format, although it is not mentioned in the 
> text.  Another typo?

My mistake - I think we have some text cleanup to do, as SAM-2 definitely
considers task management functions not to be tasks, thus avoiding issues
of what happens when a task management function is applied to a task
management function - I believe iSCSI needs to follow this route.  Julian?

Thanks,
--David
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David L. Black, Senior Technologist
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