 | | | nfs slowness with ls - but why? | nfs slowness with ls - but why? 2006-02-14 - By Stephen J. Smoogen
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On 2/14/06, David Spidley <david.spidley@(protected)> wrote:
> > -- --Original Message-- --
> > From: jch@(protected)
> > Sent: Tue, 14 Feb 2006 14:42:42 +0000
> > To: taroon-list@(protected)
> > Subject: Re: nfs slowness with ls - but why?
> >
> > David Spidley wrote:
> >
> > >Hello,
> > >I have a client mounting an nfs share.
> >>
> > >A simple "ls" is taking 90 seconds.
> > >If I disable sorting with "ls -f", it takes 3 seconds.
> >>
> >>
> Can I ask why /bin/ls -l remains slow (5.5 minutes), and why a perl 'glob "*"
' (3 minutes) of the directory is also slow?
>
I would look in nfsstat to see how many stats etc are done by the
commands. I am expecting that you are seeing something going on.. also
look for the number of retries etc.
Things that can kill NFS:
1) UDP NFS. Lots of resends especially over routers
2) Router/fragmentation. If the router is badly breaking up the UDP
packets and you are getting them in wrong order.. you will see slow
data.
3) Collisions on the wire. A bad switch or just using hubs will kill
NFS with lots of resends. [We had a problem that was due to a switch
in spanning tree mode. Turning it off increased our NFS from one box
to another by 300%.]
4) Bad ethernet driver options. A card in half-duplex on a switch with
duplex will show slow speeds on things that have lots of RPC calls in
them.
5) Bad cable. Least likely..
Seen all of these at any time, and they all would show where an
/bin/ls -f took no time and /bin/ls -l took forever. The best bets are
to look at ifconfig and nfsstat to see what the error counts and then
discount the above in whatever order is best
--
Stephen J Smoogen.
CSIRT/Linux System Administrator
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