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Date: Tue, 31 May 2005 11:56:12 -0700 (PDT)
From: Jon Dama <jd@ugcs.caltech.edu>
To: Skylar Thompson <skylar@cs.earlham.edu>
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Cc: Don Lewis <truckman@freebsd.org>, freebsd-stable@freebsd.org,
	freebsd-questions@freebsd.org
Subject: Re: Weird NFS problems
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Yes, but surely you weren't bridging gigabit and 100Mbit before?

Did you try my suggestion about binding the IP address of the NFS server
to the 100Mbit side?

-Jon

On Tue, 31 May 2005, Skylar Thompson wrote:

> Jon Dama wrote:
>
> >Try switching to TCP NFS.
> >
> >a 100MBit interface cannot keep up with a 1GBit interface in a bridge
> >configuration.  Therefore, in the long run, at full-bore you'd expect to
> >drop 9 out of every 10 ethernet frames.
> >
> >MTU is 1500 therefore 1K works (it fits in one frame), 2K doesn't (your
> >NFS transactions are split across frames, one of which will almost
> >certainly be dropped, it's UDP so the loss of one frame invalidates the
> >whole transaction).
> >
> >This is the same reason you can't use UDP with a block size greater than
> >MTU to use NFS over your DSL or some such arrangement.
> >
> >Incidentially, this has nothing to do with FreeBSD.  So if using TCP
> >mounts solves your problem, don't expect Solaris NFS to magically make the
> >UDP case work...
> >
> >
>
> The thing is that UDP NFS has been working for us for years. A big part
> of our work is performance analysis, so to change our network
> architecture will invalidate a large part of our data.
>
> --
> -- Skylar Thompson (skylar@cs.earlham.edu)
> -- http://www.cs.earlham.edu/~skylar/
>
>