[mrtg] Re: changing historical data in an RRD

Mike Mitchell Mike.Mitchell at sas.com
Wed Jul 21 23:12:55 MEST 2004


Swapping the two variables in an RRD is very easy, and doesn't involve creating a new RRD.
The two data sources are named "ds0" and "ds1" inside the RRD, and all we have to do is swap the names, not the values.

Try this:
   rrdtool tune file.rrd -r ds0:tmp
   rrdtool tune file.rrd -r ds1:ds0
   rrdtool tune file.rrd -r tmp:ds1

Replace "file.rrd" with the name of your RRD database.
This sequence renames the "ds0" data source to "tmp", then renames "ds1" to "ds0", and finally, renames "tmp" to "ds1".  Your data will now be swapped.

-----Original Message-----
From: mrtg-bounce at list.ee.ethz.ch [mailto:mrtg-bounce at list.ee.ethz.ch] On Behalf Of Arnold Nipper
Sent: Wednesday, July 21, 2004 4:57 PM
To: Eric Brander
Cc: mrtg at list.ee.ethz.ch
Subject: [mrtg] Re: changing historical data in an RRD

On 21.07.2004 21:22 Eric Brander wrote:

> Also, I know I can do an RRDTool export and get the data in an XML 
> format, but manipulating that data is my weak point. So I'm looking for 
> help on hacking the data in the RRD.
> 

doing an export an swapping the two positions is really easy. You even
don't have to know what XML is. Simply keep all the lines you don't know
what they mean and swap position in the "data" lines. A data line looks
like:

<!-- 2004-07-21 02:00:00 CEST / 1090368000 --> <row><v> 3.0291166667e+02
</v><v> 1.3062150000e+03 </v></row>

if you would like to do it with an awk-script this should do it for a
rrd with in/out:

# begin script
#
# look for data rows, $9 and $11 are the data values. Just swap, the go
to next line.
/<!--.*row/     {

        s=$9; $9=$11; $11=s; print; next;
}

# If not a data line, just print
{       print   }
#
# end script



Arnold

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