Section: mrtg (1)
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mrtg-rrd - How to use RRDtool with MRTG
After using MRTG for some time you may find some limitations, mostly in the
areas of performance and graphing flexibility. These are exactly the areas
addressed by RRDtool. To learn more about RRDtool check out its website on
When using mrtg with RRDtool you are replacing rateup with the
RRDtool perl module RRDs.pm. To enable RRDtool support in mrtg
you have to add the line
to your mrtg config file.
MRTG needs access to both the RRDtool perl module RRDs.pm and to the
If these two items are not installed in locations where perl can find them
on its own, then you can use the following two parameters to supply the
For the location of the rrdtool executable you put
For the location of the perl module it would be:
When you have made this modification to the configuration file, several
things will happen when you run mrtg again with the new config file:
mrtg will take all your old ".log" files and convert them to ".rrd"
format. (The ".log" files don't get touched in the process, so if things
don't work out they are still there.)
mrtg will use rrdtool to update its databases. These will have a new format
called rrd which is totally different than the native log format of
the classic mrtg.
mrtg will not create any webpages of graphs anymore.
It will only query the routers for traffic information and update its rrd
The advantage of whole thing is that the mrtg will become much
faster. Expect the runtime to drop to 20% of the previous value. (I would like
to get some feedback on this from folks with large installations.)
Mind you, though, while the logging process of RRDtool is very fast, you
are also gaining some time by neither creating graphs nor updating webpages.
The idea behind this is that it is more efficient to create
graphs and webpages on demand by using a cgi script.
At the moment there is no official script to do this, but two
contributers have created such scripts:
- One4All aka 14all.cgi
This was the first program to take over the webpage creation and graphing task.
It has been developed by Rainer Bawidamann
email@example.com. You can find a copy
on Rainers website: http://my14all.sourceforge.net/
The program comes with its own documentation
- routers.cgi, servers.cgi and generic.cgi
These are other cgi frontends to mrtg running with rrdtool. The main difference
between this and 14all is that the web pages it creates are much more stylish than the
ones from mrtg. These tools have been written by Steve Shipway
firstname.lastname@example.org. You can find a copy in http://www.steveshipway.org/software/
The programs come with their own installation instructions.
The mrtg-rrd script is a CGI/FastCGI application by Jan ``Yenya'' Kasprzak for
displaying MRTG graphs from data in the RRDtool format. It is an intended
replacement for the 14all.cgi script. It can make your monitoring system
faster because MRTG does not have to generate all the PNG files with graphs
every 5 minutes or so. Instead of this the graphs are generated on-demand
when the user wants to see them. http://www.fi.muni.cz/~kas/mrtg-rrd/
Paul C. Williamson has written a more in-depth page on how the whole process
works, including some performance figures. You can find his page on http://www.geocities.com/paulcwilliamson/mrtg/rateup2rrd.html
Just as a side note: MRTG-3 will be based entirely on rrdtool technology.
But don't wait for it ... get going now!
Tobias Oetiker <email@example.com>
- RRDTOOL INTEGRATION
linux.jgfs.net manual pages