[rrd-users] omit invalid values
Alex van den Bogaerdt
alex at vandenbogaerdt.nl
Fri Nov 21 16:47:56 CET 2008
----- Original Message -----
From: "Ulrich Stärk" <uli+lists.rrd at spielviel.de>
To: <rrd-users at lists.oetiker.ch>
Sent: Friday, November 21, 2008 2:14 PM
Subject: [rrd-users] omit invalid values
> I'm new to rrdtool so please be patient with me :-)
> I used ntop to populate some rrds and now want to generate custom graphs
> from those. Unfortunately some really unreasonable values got stored in
> my rrds which I neither want to be printed in my graphs nor be used for
> calculating the min/max/avg values.
> How can I tell rrdtool to just ignore values above some threshhold that
> I specify?
First you need to think about *when* you want to do so:
1: when providing rrdtool with input, thus "rrdtool update"
2: when creating graphs
In case of 1 you need to do some work, but this needs to be done only once:
You should have set appropriate minimum and maximum rates when you created
the database. See http://oss.oetiker.ch/rrdtool/doc/rrdcreate.en.html and
look for min and max.
But you already created one, so you need to "repair" it: see
http://oss.oetiker.ch/rrdtool/doc/rrdtune.en.html on how to set these new
min and max rates.
Use http://oss.oetiker.ch/rrdtool/doc/rrddump.en.html and
http://oss.oetiker.ch/rrdtool/doc/rrdrestore.en.html to make a backup and
restore it again, see 'range check' in restore.
After doing "rrdtool tune", rrdtool will ignore rates when they are outside
the limits you set. After going through "rrdtool dump" and "rrdtool
restore --range-check" rates in your RRD should be within the limits you
In case of 2 you need to do less work but your computer will need to do this
every time you create a graph. See
http://oss.oetiker.ch/rrdtool/doc/rrdgraph_rpn.en.html and look for LIMIT
(under comparing values).
This way you keep those faulty rates, you just ignore them every time you
create a graph.
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