[rrd-users] Graph from data with holes.possible?

Simon Hobson linux at thehobsons.co.uk
Wed Jun 1 10:00:03 CEST 2011

pablo wrote:

>I have performance data taken at 15min steps during the whole 24h day. (nmon
>tool for AIX)
>Now,I´d like to graph data for only the day shitf (8AM-8PM), so I'd like to
>say rrdtool "get data just for this hours interval and forget the rest".
>After some testing, i don´t know how to do it.Do you have an idea? If there
>is a 12h gap among my rrd data for each day,will be rrdtool capable of doing
>graphs without holes?

If you mean you want a graph that runs from 8am 
to 8pm, and then without a gap jumps to 8am the 
next day - then no, rrd tool cannot do that.

You could however draw a graph that shows no data 
between 8pm and 8am by using a calculation along 
the lines of :

if time between 8am and 8pm then plot_data=source_data else plot_data=unknown

Calculations such as averages would correctly 
take account of the unknown values (provided you 
use the correct function), but you would have big 
gaps in the grpahs.

If you really want the former, then you would be 
best using rrd to collect the data and store it, 
then export the data and use an external plotting 
program to generate the graphs.
Simon Hobson

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