[rrd-users] RRD Wrong (Unexpected) Values

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Tue Feb 11 16:04:34 CET 2014

> I've read carefully but didn't link it with "N" in updates. I supposed "N"
> means now and now=time() but in reality there is a difference in how 
> updates
> work between:
> N:U:488:U:U and my $n=time(); $n:U:488:U:U

First you ask for the time with "time()".  Then you start rrdtool and use 
"N". Two problems: "time()" is not accurate enough, and there will lapse 
some time when starting rrdtool.  So e.g. you record timestamp 1392101034 
but when rrdtool is doing its job it is 1392101035.125 and rrdtool is using 
that timestamp to normalize.

When using timestamps (as opposed to using "N") the timestamps are a whole 
number of seconds and in your case this means normalization doesn't make a 


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