I wrote:
> Can I confirm I have this right ...
>
> If I want to have a DS showing if the measured value was above some threshold
> (in this case, network traffic above say 80%) I can use a compute DS like :
> DS:pc80:COMPUTE:in,,GT
>
> So if the "in" value is greater than the threshold value ( here) then
> pc80 will be 1, and this will get consolidated so that later I'll be able to
> see (for example) a consolidated value that might show (say) 0.2 meaning that
> the "in" value was above the threshold for 20% of the time during that
> consolidated period.
>
> And I can add this with rrdtune with
> rrdtool tune somefile.rrd DS:pc80:COMPUTE:in,,GT
I assume it's right since there's been no corrections. Also, I assume this is
done after computing the value for each PDP - so if I have a step of 300 (5
mins) it'll compute the rate for each 5 min step before applying the RPN
expression to calculate the computed value ?
> What about if (or rather, when) I need to change the thresholds later ?
> Specifically I'm thinking that if we currently have (say) 100Mbps service,
> and we upgrade it to (say) 200Mbps, I'll need to change the threshold (and
> thus the computation for new data) without affecting historical data. I don't
> see an option for rrdtune to do this.
>
>
> Lastly, in what version does rrdtune get to add a DS ? I have 1.4.7 (Debian
> Wheezy) and the man page doesn't mention adding or deleting DSs.
And a quick test shows that "rrdtool tune test.rrd
DS:InPC:COMPUTE:In,1,/" just shows current values for the DSs without
doing anything - the same as just "rrdtool tune test.rrd". Later versions of
rrd in the Debian archives have dependencies not met on Wheezy - unless someone
felt like packaging it up for backports.
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