RE: locking errors

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From: Boris Z. (boris@conley.com)
Date: 10/07/98-02:12:48 PM Z


Message-ID: <01BDF1EB.CD362C10.boris@conley.com>
From: "Boris Z." <boris@conley.com>
Subject: RE: locking errors
Date: Wed, 7 Oct 1998 12:12:48 -0700



On Tuesday, October 06, 1998 2:57 PM, Mike Eisler [SMTP:mre@Eng.Sun.COM] wrote:
>
> > I believe the protocol should not limit servers to answer these questions as
> > they want. Some of them may want to answer "yes, yes, yes, no" and declare
> > themselves ready for 'mission critical applications'. The protocol just
> 
> Perhaps I should re-cast my 4 questions as the following requirements:
> 
> 	- NFS V4 MUST work through firewalls that block UDP and block
> 		TCP connection requests (SYNs) that originate outside
> 		the firewall.
> 
> 	- NFS V4 servers MUST NOT be required to maintain state through
> 		server reboots.
> 
> 	- The NFS V4 protocol specification
> 		MUST NOT specify a minimum or maximum lease time on the
> 		server.
> 
> 	- Clients MUST NOT expect to retain locks across network partitions
> 		that exceed a lease time.
> 
> 	- The server, and not the client ,ultimately dictates the lease time.
> 
> I think all of the above are requirements. If one thinks one or more of the
> above are not requirements, and/or thinks that the opposite of one or more
> of the above is a requirement, then that dictates a different kind of
> locking paradigm. If I interpret what you are saying, you would agree that
> the latter 4 are requirements, and the 1st one (operation through firewalls)
> is not a requirement. 
> 

I agree almost with all you 'MUST' points, it's a right words for the requirement document.
However, the case of "Clients MUST NOT expect to retain locks across network partitions 
that exceed a lease time" should not mean that client MUST re-establish ALL locks, if by 
some reason it could not renew the lease. We should allow a simple mechanism to check,
if any of the client locks are actually broken or not.

About the firewalls: we should not introduce anything in this place of the protocol
that cannot work through the firewalls. But this does not mean that I am ready to
drop UDP support!


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