collectd is a daemon which collects system performance statistics periodically
and provides mechanisms to store the values in a variety of ways, for example
in RRD files and backends like Graphite.

collectd gathers statistics about the system it is running on and stores this
information. Those statistics can then be used to find current performance
bottlenecks (i.e. performance analysis) and predict future system load (i.e.
capacity planning). Or if you just want pretty graphs of your private server
and are fed up with some homegrown solution you're at the right place, too ;).