RRDtool is the Open Source industry standard, high performance data logging and graphing system for time series data. RRD stands for "Round Robin Database". It stores data in a very compact way that will not expand over time.
RRDTool is a really good back-end for storing time-series data. If you are developing tools that need a data repository and graphing capabilities, this provides you both. You create an RRD and then you begin inserting data values at regular intervals. You then call the graphing API to have a graph displayed.
The neat thing about this data storage is its "round robin" nature. You define various time spans, and the granularity at which you want them stored. A fixed binary file is created, which never grows in size over time. As you insert more data, it is inserted into each span. As results are collected, they are averaged and rolled into successive time spans. It makes a much more efficient system than using your own complex data structures, relational database, or file system storage.
For more information on the rrd tool and platform specific binaries of the tool can be found at http://oss.oetiker.ch/rrdtool/. The installation instructions for rrd-rb can be found at wiki.
As of now there is no official release available. But the source code is available in the version control.
