[collectd] Questions on intervals, aggregate, etc...

Bryan Varner bryan at varnernet.com
Mon Apr 3 22:14:18 CEST 2017

Without getting into too many details, I'm trying to use collectd to collect analog -> digital readings of a sinusoidal analog input.
I'm using the 'sensors' plugin with an interval of 0.01 seconds, and have my normal interval set to 5 seconds.

I'm writing metrics out to write_graphite, I'm skipping RRDs for this one if I can.

Metric gathering & reporting is working exactly as I expected, and performing well.

I'd like to be able to calculate the RMS of the sinusoidal values for every 1 second interval, and send an RMS to graphite.

I don't see anything in the aggregation plugin to do that kind of calculation, which is fine -- I'd be happy to add it, but I have this sneaking suspicion that the aggregation plugin isn't going to do what I really want, which is to operate as a write_plugin, collecting metrics from the sensors plugin, but also acting as a read plugin that emits the RMS for the sensors values since the last read interval.

Is what I'm looking for here even feasible with existing plugins?

I'd rather pay for the calculation cost up-front and only incur it once (while collecting) rather than have to do these calculations every time a client tries to do reporting / rendering of the data.

Any help would be appreciated.


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