[rrd-users] Merging some graphs

Simon Hobson linux at thehobsons.co.uk
Fri Sep 24 20:20:13 CEST 2010

Sergey wrote:

>I wanted to clarify whether there are ready-made methods for combining.

Not really, RRD Tool is a general purpose tool, and people use it for 
all sorts of things. Apart from packages that use it (like Cacti), 
pretty well most installations are custom built.

So if you are wanting a graph with disparate things plotted on it, 
you'll have to decide what sort of scales each source will need, and 
how to scale each source so they can share a common graph scale.

For things as highly variable as data throughput and error rates (ie 
where it probably isn't practical to decide in advance what an 
appropriate scaling factor would be), another option would be to draw 
two graphs - exactly the same width and time period, leave the legend 
off the first, and display them one under the other. You can either 
add a combined legend to the second graph, or extract the numbers and 
display them as part of the web page.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
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