RRDtool

RRDtool is a program that is stored with the time-based measurement data can be summarized and visualized. The program was originally developed by Tobias Oetiker and licensed under the GNU General Public License ( GPL). By publishing as free software now many other authors have contributed new functionality and bug fixes. RRDtool is available as source code and as an executable program for a lot of operating systems.

The abbreviation RRD stands for " Round Robin Database " and refers to the way in which are stored in the data RRDtool. When you create a database, a so-called " RRD file ', enough memory for a specified period of time is created. After this period, the database is not extended (the file is not increased ), but the oldest data is overwritten. This " round robin " method is known in computer science as a ring buffer.

The user interface consists of RRDtool command-line programs. This RRDtool can be used by other programs to store data and create graphs, application programming interfaces ( APIs) for multiple programming languages ​​are available, including C and Perl.

Usually RRDtool is not used directly from the command line, but serve other programs as data storage or source. Examples of FOSS programs that use RRDtool, Cacti are, MRTG and Munin. A longer list of programs that use RRDtool, located on the RRDtool homepage.

Round-robin archives

Depending on the period of time is shown in a graph, the data are needed in different resolutions. Often there is a few periods of time that are of particular interest, for example, "a day ", "a week ", " one month ," and "one year ". RRDtool takes advantage of this in order to compress data automatically ( summarize ).

For any desired length of time a " round robin archive" (RRA ) is applied, which can accommodate a fixed number of data points. This space is then filled with the round-robin method. Each RRA is assumed to reflect a resolution which ( together with the number of data points) determines the amount of time is saved for the data. As more data points are grouped together, defines the "Consolidation Function" ( consolidation function CF) firmly. The most frequently used functions are average, minimum and maximum.

Available versions

Currently (April 2009), there are two stable release branches, version 1.2 and the version number 1.2. * And version 1.3 and the version number 1.3. *. In principle, only flow error fixes in the stable release branches a. New features are developed in the source code management system and be in the next stable release branch, version 1.4, to be included. Occasionally there are exceptions to this rule. Some time ago, the initiator of the project called for the collection of ideas for RRDtool 2.x.

New features in version 1.3

The following features and enhancements found in version 1.3.

• Faster file access through the use of memory mapped I / O.
• Using Cairo and Pango for generating graphs.
• Alternative version of the Holt- Winters algorithm.
• Support for localized help messages was prepared.

Created with version 1.3 RRD files are backward compatible with version 1.2, except when the new version of the Holt- Winters algorithm is used.