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Original author(s)Tobias Oetiker
Initial releaseJuly 16, 1999; 25 years ago (1999-07-16)
Stable release
1.8.0 / 2022-03-13[1]
Written inC
LicenseGNU General Public License
RRDtool has a graph function, which presents data from an RRD in a customizable graphical format.

RRDtool (round-robin database tool) aims to handle time series data such as network bandwidth, temperatures or CPU load. The data is stored in a circular buffer based database, thus the system storage footprint remains constant over time.

It also includes tools to extract round-robin data in a graphical format, for which it was originally intended. Bindings exist for several programming languages, e.g. Perl, Python, Ruby, Tcl, PHP and Lua. There is an independent full Java implementation called rrd4j.

General data storage


RRDtool assumes time-variable data in intervals of a certain length. This interval, usually named step, is specified upon creation of an RRD file and cannot be changed afterwards. Because data may not always be available at just the right time, RRDtool will automatically interpolate any submitted data to fit its internal time-steps.

The value for a specific step, that has been interpolated, is named a primary data point (PDP). Multiple PDPs may be consolidated according to a consolidation function (CF) to form a consolidated data point (CDP). Typical consolidation functions are average, minimum, maximum.

After the data has been consolidated, the resulting CDP is stored in a round-robin archive (RRA). A round-robin archive stores a fixed number of CDPs and specifies how many PDPs should be consolidated into one CDP and which CF to use. The total time covered by an RRA can be calculated as follows:

time covered = (#CDPs stored) × (#PDPs per CDP) × (step time length)

After this time the archive will "wrap around": the next insertion will overwrite the oldest entry. This behavior in this context is referred to as "round-robin" and is the reason for the program's name. However this is different from the common computer science definition, which is a method of distributing resources among multiple consumers or processes.

To cover several timespans and/or use several consolidation functions, an RRD file may contain multiple RRAs. The data retrieval function of RRDtool automatically selects the archive with the highest resolution that still covers the requested timespan. This mechanism is also used by RRDtool's graphing subsystem.

Release history

Colour Meaning
Red Release no longer supported
Green Release still supported
Blue Future release

The following table contains the release history of RRDtool, showing its major releases.

Version number Date Links Notable changes
1.0 July 16, 1999 Full release notes, Announce First release. Basically MRTG "done right".
1.1 April 25, 2005 Full release notes, Announce libart; output EPS, PDF & SVG; VDEF; trends; percentiles; updatev; Holt-Winters Forecasting; COMPUTE; .rrd format change.
1.3 June 11, 2008 Full release notes, Announce Safer & faster file access; cairo/pango; anti-aliasing; TEXTALIGN; dashed lines; new HWPREDICT; libxml; i18n; XML dump;
1.4 October 27, 2009 Full release notes, Announce Caching daemon; VDEF PERCENTNAN; CDEF PREDICT & PREDICTSIGMA; libDBI; graph legends positioning; Lua bindings; 3D border width; and more ...
1.5 April 16, 2015 Full release notes, Announce Use data from callback functions; Population of new rrd files with data from old ones; .NET bindings
1.6 May 9, 2016 Full release notes, Announce Thread Safety
1.7 May 17, 2017 Full release notes Results of code audit; overhaul of the Python bindings; various other small feature improvements
1.8 March 13, 2022 Full release notes ROUND function for rrd RPN, vcpkg support for MSVC builds, first_weekday for Windows port, x64 platform for win32 build, --add-jsontime for graphv, add --utc to graph, automated testing for win32 builds, support TUNE command in rrdcached

Other tools that use RRDtool as a DBMS and/or graphing subsystem


See also



  1. ^ "Releases · oetiker/Rrdtool-1.x". GitHub.