Re: iSCSI : Command Ordering Proposal.

[Ralph Weber <ralphoweber@compuserve.com>]

One of the masters from whom I learned programming repeatedly advised,
"Never under estimate the creativity of those who use your programs."

In this case, there are two architected capabilities:

  1) At the client-server level, there's Ordered Tags, and
  2) At the transport level, there's CRN ordering.

True, most applications will want to coordinate the usage of the
two.  In my opinion, it is less likely that applications will
want to disable CRN for Simple tags since I perceive the benefits
of transport ordering as having broader link reliability
implications.

I can more readily agree that use of an Ordered tag strongly
suggests use of CRN.  However, I once helped design an application
where only the Ordered Tag guarantee was needed.  Our cluster
application sought only to obtain the following guarantee from the
target: "When status is returned for this (ordered) command, all
commands received prior to this (ordered) command from all initiators
also have been completed."  By design, our application took care of
all the other ordering details and the our application had to do
that because it was dealing with multiple initiators.

Based on my experience, I'd ask you to ensure that the standards
contain all the tools application clients need but to refrain from
dictating how those tools are used.

Thanks.

Ralph...