[rrd-users] MAXIMUM consolidation over the sum of two counters

Simon Hobson linux at thehobsons.co.uk
Tue Aug 27 10:37:33 CEST 2013

Dick van der Sijs wrote:
> However, the way I understand that rrdtool works is that with rrdgraph I cannot get max(counter1+counter2).

> That is, not unless I set up a third counter from the start in which I put the sum counter1+counter2.
> The question is then if it is possible with rrdgraph alone, so without that third counter that I mentioned?
> Note that I am not looking for max( max(counter1),max(counter2) ), but really for max(counter1+counter2).

You've already answered your own question - it's impossible once you've applied any consoilidation because the values you want simply do not exist.

To get max( counter1 + counter2 ) then you **MUST** store counter1+counter2 prior to applying consolidation.

I have a couple of things I'd like to do which have the same problem. Only I haven't yet figured out the best way to reliably and simply fetch values from multiple remote systems (and allowing for the possibility of one or more being down) so I can store the sum of the values.

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