Re: PostgreSQL, NetBSD and NFS

Tom Lane wrote:
> Greg Copeland <greg(at)copelandconsulting(dot)net> writes:
> > On Wed, 2003-02-05 at 11:18, Tom Lane wrote:
> >> Wild thought here: can you reduce the MTU on the LAN linking the NFS
> >> server to the NetBSD box? If so, does it help?
>
> > I'm curious as to why you think adjusting the MTU may have an effect on
> > this. Lowering the MTU may actually increase fragmentation, lower
> > efficiency, and even exacerbate the situation.
>
> I'm thinking maybe one or both LAN cards have a problem with packets
> exceeding a certain size.

But he's using NFS over TCP, so any traffic that gets truncated or
dropped should simply result in a TCP retransmit (since the packet's
data won't match its checksum anymore, and it'll get dropped on the
floor).

Of course, if the NFS layer is actually transferring data via UDP
despite explicitly being told to mount via TCP, that's something else.
It might be useful to verify via netstat that an actual TCP connection
to the NFS server is being established and used.

Makes me wonder if this might be a problem at the NFS protocol
layer...

--
Kevin Brown kevin(at)sysexperts(dot)com