[Solution] Ubuntu 12.04 NFS Shares cause high CPU load + dropouts after upgrade from 10.04

After upgrading our Ubuntu Server from 10.04LTS to 12.04LTS, we noticed a severe decrease of Performance of our FOG Server.

Transfer times of the images were drastically higher (few hours instead of +- 20minutes) and very often the transfer would fail after a few GB.

Noticed that during transfer (which uses NFS), the cpu load on the Server is very high (+10)

Found out that this bug is known since 2012.

Some sources tend to blame NFSv4 for this behaviour.

After investigation, it seems that during the upgrade process nfs* packages were not upgraded, even though the server was updated regularly with apt-get-dist-upgrade  :

dpkg -l nfs-kernel-server

ii  nfs-kernel-server       1:1.2.0-4ubuntu4.2           support for NFS kernel server

Force the update :

apt-get install nfs-kernel-server

this will also pull updates for package nfs-common.

So after the update :

dpkg -l nfs-kernel-server

ii  nfs-kernel-server       1:1.2.5-3ubuntu3.1           support for NFS kernel server

With this being done, our FOG Server is now working again, at full Speed without any trouble.