[Gluster-users] Some client problems with TCP-only NFS in Gluster 3.1

Stephan von Krawczynski skraw at ithnet.com
Fri Oct 22 13:47:24 UTC 2010

On Fri, 22 Oct 2010 15:18:09 +0200
Beat Rubischon <beat at 0x1b.ch> wrote:

> Hi Stephan!
> Quoting <skraw at ithnet.com> (22.10.10 15:05):
> > We never experienced any performance problem with NFS over UDP.
> Be careful when using NFSoUDP on recent networking hardware. It's simply too
> fast for the primitive reassembly algorithm in UDP. You will get silent data
> corruption.
> SuSE warns about this fact quite some years in their nfs manpage. You'll
> find a lot of copies when Googleing the title "Using NFS over UDP on
> high-speed links such as Gigabit can cause silent data corruption."
> Beat

Hi Beat,

you are talking of the problem with identification field being only 16 bit,
We experienced this scenario to be far less severe than TCP busted by packet
drops. In fact we were not able to run NFS over TCP for more than 2 days
without a complete service breakdown. Whereas UDP runs for several years now
without seeing the corruption issue.
We were very astonished about the bad tcp performance, but we had to accept it
as a fact.


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