How can I update data with RRDtool?

perl rrdtool rrd
rss picture rss · Nov 30, 2008 · Viewed 11.2k times · Source

I am using RRDtool for storing data for displaying graphs. I update the RRD by RRDs::update and this fails when trying to rewrite the information, means update data for a time in the past (e.g. someone moved the system timer back). The error I get is: 

ERROR: Cannot update /opt/dashboard/rrd/Disk/192.168.120.168_disk_1.rrd with 
'1228032301:24:24' illegal attempt to update using time 1228032301 when last 
update time is 1228050001 (minimum one second step)

I want to always allow the rewrite, how can I do this?

Answer

Tobi Oetiker picture Tobi Oetiker · Jul 20, 2012

rrdtool does not write your input into the rrd file. It rather samples what you enter and then stores the resulting datapoints. So providing 'old data' to rrdtool update will not work in the same way, as you can not easily skip back in a sound recording to 'fix' a few bad notes.

Obviously there are ways to alter old data, the way todo this in rrdtool, is to 'dump' the rrd file to xml, modify the content and 'restore' it. Not something one would like todo on a regular basis.

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