[rrd-developers] How to create a new Data Type and Consolidation Function?

Tobias Oetiker tobi at oetiker.ch
Thu Feb 3 22:48:48 CET 2011

Hi Long,

Today long wrote:

> Hi,
> We need to graph a COUNTER (as input) but for output, instead of a rate of
> change, we simply need the difference against the previous reading (instead
> of difference against the previous reading divided by the polling period in
> seconds, as the existing COUNTER data type of RRDTool).
> So, we need to create a new Data Type.
> Also for Consolidation, we would like to simply add all the values, so a new
> Consolidation Function is needed as well (in addition to the existing
> The use case is we would like to have a total of all the count over the
> measurement period (5 mins, 30 mins, 1 hour, ...). So we need a total, not a
> rate for 5 mins, then for 30 mins, 1 hours ... and so on.
> We've been using Cacti, which uses RRDTool so we have a solid understand of
> what RRDTool can do and can not do.
> However, we have never tried to develop code for RRDTool before. Please let
> us know any coding guidelines, patch submission process ... anything to help
> us create a new Data Type and CF, make sure the graph generation is still
> working, being able to patch our current RRDTool, contribute to your code
> repository so the next release of RRDTool will have the new feature
> built-in. Any of these information will be very appreciated.

I have a premotion this might be a long discussion, but maybe we
can cut it short, let me try:

If you want to know the total amount of traffic for a periode of a
day (example), just ask rrdtool for the avarage rate of traffic for
a day and multiply this number with the number of seconds in a day

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900

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