[rrd-users] RRDs Coding Question - Dynamic Multiple RRD Data Sources

Simon Hobson linux at thehobsons.co.uk
Mon Sep 24 22:26:24 CEST 2012

Wesley Wyche wrote:
>Yes, I speak Perl.  I was referring to the RRDs perl module (in the subject
>of this thread) with this question.  Was hoping there was a wildcard way to
>do this.

Highly unlikely. If you think about it, it would be to all intents 
impossible to code anything meaningful - meaning something that would 
work for other than a narrow set of conditions.

Just for starters, when the user graphs them, should the different 
sets of data be stacked or overlaid ? What set of colours should be 
used ? What about the situation where one set of data needs to be 
stacked, and then another set done in a separate stack* ?
If the user creates some VDEFs and puts them in the legend, should 
they be summed ? How would that work for anything but average ?
The only sensible way is to let the user sort all that out and tell 
RRD exactly what they want.

* That's one I have. Plot all the inbound traffic as a stack, then 
plot all the outbound traffic as a separate stack (having multiplied 
all the values by -1) - give a graph with inbound traffic by IP above 
the X axis in a stack, and the outbound traffic by IP in a stack 
below the X axis. Gets "quite busy" with lots of IPs - I have one 
with all 254 addresses in a class C ! Still no idea how to handle 
IPv6 :(

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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