[mrtg] TrafGrapher - interactive multiple MRTG data in one graph

[Steve Shipway]

So, if I understand you correctly, then TrafGrapher is a complete replacement for MRTG (replacing the collector, storage and web frontend), though it does have a built-in migration path (it will migrate an MRTG .log datafile).

So, since it uses its own data storage backend (text files, similar but not identical to Native MRTG files) it will not use RRDTool, and you've addressed the MRG Native-mode IO performance issues with your own collection/storage engine.  Data aggregation is only performed once per day, rather than on each update in a heirarchical mode as MRTG and RRDTool do, by summarising a file that is incrementally appended to.

My first query would be on how the graphing performance handles on the fly graph generation efficiently, since  you'll have to do a lot more on-the-fly aggregation than MRTG/RRD do due to your aggregation being done only once per day.   Also, although you are only appending a single log line, you could find the log file grows rather large by the end of the day as opposed to the static size of MRTG/RRD (which minimise their IO by memory-mapped IO and writing just the updated bytes, not the whole file).

You will also have a larger file, as you're storing in a text format rather than binary; however, that would certainly make the data files more portable between architectures, which is one of the problems with RRD files.

If you want to add support for RRDTool, there are a large number of libraries available to let you access the data with simple function calls.  You can always extract the data locally and still send the data as text to the javascript client, of course.

Best of luck with it all; I would maybe suggest that you concentrate on the UI and collector, and maybe use RRDTool as the storage - since it would be hard to beat the efficiency of the RRD engine, but both MRTG and the currently available web interfaces to it are a bit dated.

Steve

Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
s.shipway at auckland.ac.nz
Ph: +64 9 373 7599 ext 86487