[collectd] generating composite metrics

Gerardo Herzig gherzig at fmed.uba.ar
Sun Jun 29 02:24:12 CEST 2014

Thank you very very much for your time. Im not a Java guy, but it looks like riemman deserves some reading.


----- Mensaje original -----
> De: "Marc Fournier" <marc.fournier at camptocamp.com>
> Para: "Gerardo Herzig" <gherzig at fmed.uba.ar>
> CC: "collectd" <collectd at verplant.org>
> Enviados: Viernes, 27 de Junio 2014 2:48:32
> Asunto: Re: [collectd] generating composite metrics
> Hello,
> Excerpts from Gerardo Herzig's message of 2014-06-25 18:14:10 +0200:
> > Hi all. Im wondering if it is possible to generate a metric as a
> > calculation between others.
> > 
> > Example I: Know the rate between the "used memory" and the "total
> > memory".  Example II: Know the rate between "In use" apache threads
> > against "total" apache threads.
> As a side note, the master branch has a patch which allows the memory
> plugin to emit percentages instead of absolute values. Maybe this
> could
> solve example 1 in a way ?
> > I know how to make a graph as this sort of calculations, but i also
> > need to generate an alert when, say, 75% of the apache's threads
> > are
> > in use, so the graphical solutions does not cover all my needs.
> > 
> > So i guess the correct solution is to generate my own .rrd files
> > according to existing .rrd files. I just dont have any idea how.
> I like using riemann for this sort of use-cases (http://riemann.io).
> Basically, you just use collectd to collect metrics from your systems
> and send them to a riemann server using the write_riemann plugin.
> Then
> do the calculations/aggregations/correlations (and optionnally, the
> alerting based on the result) in riemann.
> If you're tied to having the resulting values in RRD files (which
> riemann doesn't know about), you can run riemann embedded in collectd
> using the java language binding plugin. This way you can do the
> filering
> and calculations you want using riemann, and have the results passed
> down to collectd's rrdtool/rrdcached plugin. Search for "collmann" on
> github for the details.
> Marc

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