[mrtg] Counts disappear after a few months

Steve Shipway s.shipway at auckland.ac.nz
Wed Mar 27 09:46:53 CET 2013

>Apparently, MRTG looses counts. Is this a known bug? We run MRTG 2.17.2.

I've never seen such a bug (so far).  Remember, though, that RRDTool (and MRTG .log files) operate in round-robin mode, automatically expiring old data as they go.

You dont say if you're using MRTG in Native or RRDTool mode.  If in RRDtool mode, have you ever tuned the RRDRowCount variables?  Take a look at the 'rrdtool info' for the relevant RRD file.  It is possible that it is missing the 'Yearly' RRA, causing it to fall back to using the 'monthly' RRA for the yearly graph - and the 'monthly' RRA is about 2 months long, exactly the time period after which you say your data vanishes.

I suspect your yearly graph is using your monthly RRA and so the data is expired after 2 month as intended.  Either the Yearly RRA is missing ,or truncated.  The rrdtool info output will show which, and in either case, fixing shouldnt be too hard using rrdtool tune.


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

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