> > These machines get most of their traffic as NFS clients but they also
> > export some local filesystems.
> > 
> > It's unclear what exactly causes systems lockups. So far there is a
> > strong correlation between system getting stuck and compilation on the
> > NFS-mounted filesystem. Lockups do not happen during the night, so it
> > must be related to some user activity. 
> 
> Hm.. it sounds like this is related to a machine being both a client
> and a server, and having traffic for both functions. It's not
> a configuration that is used often. Try pushing a machine using
> it both as a client and a server, I suspect you may see the hangs
> more often.

FWIW, at work we have a whole lot of netbooted i386 machines with
/ and /usr on NFS, and they regularly experience the "lock up for
a second" problem - but it gets far worse if there's extra broadcast
crap on the network. 

(The netboot boxes don't export any filesystems, either.)