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Re: [Question #148743]: intelligent scaling for derivatives

 

This request doesn't make much sense to me.  If you want bytes/sec, why aren't you sending that data to Graphite?

I think a much better solution would be to send the actual data you want to graph to graphite, rather than trying to calculate it after the fact.

-Nick

On Feb 21, 2012, at 3:55 AM, redbaron <question148743@xxxxxxxxxxxxxxxxxxxxx> wrote:

> Question #148743 on Graphite changed:
> https://answers.launchpad.net/graphite/+question/148743
> 
> redbaron posted a new comment:
> Question doesnt look answered to me. Indeed, we need some intellegent
> scaling function which can detect current data resolution.
> 
> Just to make things clearer. Lets say we have 10s resolution for 1 day
> and 1minute resolution for 7 days , and have a gauge metric, lets say
> "net.eth0.tx.host1", same number as you see in ifconfig output.
> 
> Then we want to plot a bytes/second graph. How to do it? FIrst we
> calculate "derivative(net.eth0.tx.hos1)", but it gives us
> bytes/<resolution in seconds> , which is not we want. To gets bytes/sec
> we need to scale derivative by 1/10 (to have 1sec value out of 10 sec),
> so we plot "scale(derivative(net.eth0.tx.hos1),0.1)" and it works
> perfect but have 2 problems:
> 
> - If we decide to change retention params we need to redo all our graphs
> - If we try to display this graph for time period longer than "10s" resolution will drop to 60 seconds, derivative will return value "bytes/60seconds" therefore we need to change scale from 0.1 to 1/60 
> 
> What is needed is an intelligent scale function to be able to define
> graphing options once and get correct values for all resolutions.
> 
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