I have two FreeBSD clients NFS mounting a volume from a Filer. The versions are 3.4 and 4.0.
When NFS is being used the memory usage of both machines climbs steadily and a reboot occurs (about 2-3 times per day).
Sounds odd. Are you sure that this has got to do with NFS usage? I haven't used 4.0 in production, but 3.x was pretty solid, and the only times that these boxes are rebooted is for kernel upgrades.
How do you define "out of memory", and what sort of things are these boxes doing?
Nick