High Availability NFS Server (Heartbeat/DRBD) long hang on clients when takeover occurs
Solution 1:
If you're running Ubuntu with GUI user logins such as LTSP, it's very possible that the clients are the problem.
The Gnome-Settings-Daemon has a nasty habit of digging around inside the NFS mounts to check the state of any trash folders it finds. This problem exists in Ubuntu 9.10 and likely also in 10.04.
This is hard-coded in the Ubuntu distribution and was erroneously dropped in the 9.x releases. It is reported to be fixed in later Ubuntu releases and a common symptom is high load average while the NFS mounts are unreachable.