[rrd-users] Aggregate/combine several RRDs

[Raimund Berger]

Jesper Skou Jensen <jesper.skou.jensen at uni-c.dk> writes:

> Thank you for your answers guys, now I'll just have to whip up a little 
> script to go through the RRD's.

You may likely not even need a script to "go over". Simon sketched out
an example of how to draw from several RRD sources and apply
aggregatory functions in one single (!) graph call.

More specifically, the source RRDs in those DEFs can be different, so
you can define variables for data pulled from several sources and then
apply computations on them, in a single run. Just read the rrdgraph
man pages, and you'll see it's really not that hard.

The question is still of technical interest though, whether to create
intermediate RRDs for this kind of usage. This basically boils down to
the computing versus storage cost question I guess, plus the issue of
creating an additional point of error/failure.

I'm not currently aware of rrdtool directly supporting this kind of
intermediate RRDs, but would be interested to hear if somebody made
an attempt on this and got it working.