Description:

RRDtool (Round Robin Database Tool) sets the open source industry standard for high-performance time series data logging and graphing. Known for its ability to quickly generate graphical representations of the data values collected over a definable period of time, RRDtool  can be used to write custom monitoring shell scripts or to create whole applications using its Perl, Python, Ruby, Tcl (Tool Command Language) or PHP (originally Personal Home Page) bindings.

Usage Notes:

Additionally, RRDtool lets you update the logfile at any time. It will automatically interpolate the value of the data source (DS) at the latest official interval, and write this interpolated value to the log.