NAME
mrtg-rrd - How to use RRDtool with MRTG
SYNOPSIS
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
http://oss.oetiker.ch/rrdtool
RRDTOOL INTEGRATION
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
LogFormat: rrdtool
to your mrtg config file.
MRTG needs access to both the RRDtool perl module RRDs.pm and to the
rrdtool executable.
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 appropriate directories.
For the location of the rrdtool executable you put
PathAdd: /usr/local/rrdtool/bin/
or
PathAdd: c:\rrdtool\bin
For the location of the perl module it would be:
LibAdd: /usr/local/rrdtool/lib/perl/
or
LibAdd: c:\rrdtool\bin\lib\perl
When you have made this modification to the configuration file, several
things will happen when you run mrtg again with the new config file:
1. 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.)
2. 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.
3. mrtg will not create any webpages of graphs anymore. It will only
query the routers for traffic information and update its rrd
databases.
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
rainer.bawidamann@web.de. You can find a copy on Rainers website:
http://my14all.sourceforge.net/ The program comes with its own
documentation
routers2.cgi
This is another CGI frontend for 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, plus they
support User Defined summary graphs and different levels of
Authentication and Authorisation. This has been written by Steve
Shipway (steve@steveshipway.org). You obtain a copy, and find a
forum and demonstration system at
http://www.steveshipway.org/software/ The program comes with its
own installation instructions and install script.
mrtg-rrd
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
FUTURE
Just as a side note: MRTG-3 will be based entirely on rrdtool
technology. But don’t wait for it ... get going now!
AUTHOR
Tobias Oetiker <tobi@oetiker.ch>