Collectd – Linux System Statistics Collection Daemon

collectd is a small and modular daemon written in C for performance which collects system information periodically and provides means to store the values. Included in the distribution are numerous plug-ins for collecting CPU, disk, and memory usage, network interface and DNS traffic, network latency, database statistics, and much more. Custom statistics can easily be added in a number of ways, including execution of arbitrary programs and plug-ins written in Perl. Advanced features include a powerful network code to collect statistics for entire setups and SNMP integration to query network equipment.

Installation
OpenSuSe user can install collectd using "1-click" installer - here
Debian/Ubuntu user can install collectd using command: apt-get install collectd
For Red Hat, CentOS and Fedora, there are collectd RPM packages in Dag Wieers' repository.

Configuration:
The configuration will lie in /etc/collectd.conf. Open the file and pay particular attention to the LoadPlugin lines : # vi etc/collectd.conf

For each plugin, there is a LoadPlugin line in the configuration. Almost all of those lines are commented out in order to keep the default configuration lean.

There's a wiki page containing a table of all plugins.

The Interval setting controls how often values are read. You should set this once and then never touch it again.

If you're done configuring, you need to (re-)start the daemon. If you installed a binary package there should be an init-script somewhere. Under Debian, the command would be:

# /etc/init.d/collectd restart

You also need to configure your webserver (apache) to display the rrd graph:

<IfModule mod_cgi.c>
    ScriptAlias /collectd /srv/www/collectd/collection.cgi
    <Directory "/srv/www/collectd">
        Order allow,deny
        Allow from 192.168.1
    </Directory>
</IfModule>

Restart your apache server and browse to http://localhost/collectd