Nagios monitors your network in real-time, and raises alarms, but if you want an history of the values returned by plug-ins, you have to use an add-on. You can find a few of those on NagiosExchange.

The easiest add-on to install and configure is, as far as I'm concerned, Nagiosgraph. No need for a database, all values are stored in a RRD file, thus making it easy to create graphs. It can extract data either from the plug-ins' perfdata or output.

Its configuration is way easier than NagiosGrapher's. NagiosGrapher has prettier graphs, and can generate automagically the proper configuration of Nagios when new services are added. But it needs a Perl service running permanently in the background, exotic Perl packages, heavier configuration. And automatically changing Nagios' configuration is a risky task.

But if you're not afraid, I guess you will be more satisfied with NagioGrapher. If you're as lazy as I am, keep on reading how to run Nagiosgraph.

This tutorial exposes the method I used to send hardware notification from DELL servers to Nagios.

I rely on the software DELL gives away with its servers, named OpenManage. OpenManage is instructed to run a command whenever a hardware problem happens, and this command sends a passive check to Nagios.

Another way to inform Nagios of hardware events is to have OpenManage send SNMP traps to Nagios.