Ganglia is a monitoring framework for clusters of servers. It records many statistics and can record custom defined ones too. It works in a distributed manner, with each machine you wish to collect statistics for running the Ganglia monitor deamon, gmond. Each monitoring deamon’s statistics are collected by a metadata daemon, gmetad, running on either one of the monitored hosts or a separate machine. Ganglia provides a PHP frontend which displays the data from gmetad in the form of pretty graphs.
The steps required to install Ganglia, as with many pieces of distributed software, are not immediately obvious. This is a guide to getting it up and running on Ubuntu. As I install it from source, it should be portable to other distributions, although the package names for dependencies are Ubuntu specific.
The guide is quite long, so I published it on Google Docs rather than making a huge post here.