Subject: [nfsv4] V4.0 support requirements

From: "Noveck, Dave" <[email-masked]>
Date: Sun, 16 Jul 2006 09:49:37 -0400

I've just created issue 92 for this. Text for the issue description 
follows:
 
Currently, inherited from RFC3530, we have the requirement that a 
v4.1 server MUST support v4.0 and similarly that a v4.1 client MUST 
support v4.0.

There are some good reasons to consider weakening these, to SHOULD 
perhaps.  The basic reason is that we have eliminated a whole bunch 
of complexity with regard to  management of sequence state for owners 
and the associated replay protection.  With the implementation of 
sessions, none of that complexity is required but a MUST would make 
it required, so you would wind up having to implement both sessions 
and the old-style replay protection.

A large part of the purpose of simplifying the protocol is to 
simplify the task of impementation, but a requirement to implement 
both would mean that it was more complicated.  Until v4.1 is ubiquitous,
clients and servers are going to have to support v4.0 anyway so the 
mandate has no purpose at that point.  But once v4.1 is ubiquitous, why 
should we force people to do this extra implementation?  The other thing

here is that we may force people to implement this but we can't force 
them to implement it well.  If we are in the v4.1 world and everybody 
has to say that they support v4.0 then they will, even if the testing 
is quite sketchy.  It would be far better if people could distinguish 
between those that really supported v4.0 and those that didn't and that 
would be easier without the requirement.

I think this issue is tied to the fact that we have made sessions 
mandatory.  If v4.1 simply consisted of optional additions then the 
MUST for supporting previous versions would be quite viable.

I had considered afddressing this issue in v4.2 by which time 
v4.1-ubiquity would be on the horizon.  However, we really can't be 
sure there will be a v4.1 so I think we should address this now.

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From: Spencer Shepler <[email-masked]>
Date: Tue, 25 Jul 2006 04:29:04 -0500

This approach is fine with me.  I might suggest that the issue
be generalized to making changes in the minor versioning rules
since we have broken rule #12 with the sessions decision.  We should
reflect that and any other changes needed.

Spencer