RRDtool – is a software tool for data logging and graphing of time series data, such as network bandwidth, temperatures, CPU load, etc.
RRDtool stands for round-robin database tool, because it stores the data in a circular buffer based database that has a fixed size and a fixed time span. This means that the data is automatically aggregated and archived according to different resolutions and consolidation functions, such as average, minimum, maximum, etc.
RRDtool can be easily integrated in shell scripts, perl, python, ruby, lua or tcl applications. It also has a graph function that can present the data in a customizable graphical format, such as PNG, EPS, PDF or SVG.
RRDtool can be used for various purposes, such as monitoring system performance, network traffic, weather data, sensor readings, etc. It can also be used for forecasting and anomaly detection using Holt-Winters algorithm.
You can download RRDtool from its website