RRDtool is time-series data storage and graphing utility created by the author of MRTG. Using RRDtool, you can write your own MRTG-like tools in a matter minutes with only a few lines of Perl or shell code.

RRDtool is a round-robin database tool by http://people.ee.ethz.ch/oetiker Tobi Oetiker. It is designed to handle time-series data like network bandwidth, temperatures, CPU load etc. The data is stored in round-robin database so that system storage footprint remains constant over time.