[mrtg] Strange MRTG problem
Alex van den Bogaerdt
alex at vandenbogaerdt.nl
Wed May 15 11:09:22 CEST 2013
> In Cacti, I get the correct value (approximately 700-800Mbps per second.)
> In MRTG, it is never more than 190-200Mbps.
In addition to what Steve already said:
Monitor your RRD file. Look for the counter values being put in, and the
timestamps this happened (rrdtool lastupdate, or rrdtool info)
Do the timestamps have expected values? If not, your crontab may need to be
Then look at the counter values being collected. Do the computations
yourself (subtract previous counter value from the current counter value,
subtract previous timestamp from the current timestamp, compute
delta(countervalue)/delta(timestamp). Is the result close to what you
expect to get, or is it close to what MRTG reports? This should help you
figure out if it is collecting the counters which fails or if it is
processing them further which fails.
Also check your config file for typos. Use any tool you feel comfortable
with, except your own eyes and brains; let the machine do the work (e.g.
grep). Maybe you find a typo which results in different behaviour than you
expect. That typo could be in another part of your config, overriding what
you think you have set for DAS-c3229.
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