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Re: nfs is very slow

On Thu, Aug 07, 2003 at 05:39:55PM +0200, Nicos Gollan wrote:
> On Thursday 07 August 2003 14:01, Gregor Stößer wrote:
> > I'm having some trouble with my nfs-server. Performance is very bad, but
> > all ather protocols (ftp, http, scp) are quite fast.
> ftp, http et al. use TCP connections while NFS per default uses UDP packets. 
> More recent kernels have experimental support for NFS over TCP. In your case 
> (fast network where latency is a very limiting factor), there might be a 
> problem with NFS sending small packages and needing confirmation on every 
> one, thus adding a huge overhead, while TCP scales better. If you find a way 
> to increase packet sizes - gigabit ethernet should support around 65kB -, you 
> might actually see a performance increase.

I'm using already read- and write sizes of 64kB, that's not the point.
But NFS over TCP might be worth trying. Nevertheless, my machine worked
without any problem for more than a year, so changing from UDP to TCP
might help, but there must be some other reason.

> And something that got me: be sure you are not running IDS software like 
> snort, or if you need it, make sure it ignores NFS traffic. I had the problem 
> that after some two minutes of nfs use, my root partition was mysteriously 
> full. It turned out that snort wrote a detailed report on each and every 
> packet the server received. I don't know if this had any impact on 
> performance (relatively slow network), but I don't think a thing like this 
> goes unpunished.

There is definitely no firewall, sniffer or anything else running in my
internal network, I have just a firewall on the network card with my
public address.

> -- 
> Got Backup?
Yes, of course !


 Gregor Stößer     email: gregor.stoesser@chemie.uni-karlsruhe.de
 Institut für Anorganische Chemie
 Universität Karlsruhe                          Tel: 0721/608 2988
                                                Fax: 0721/608 4854

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