[rrd-users] Unexpected decimal values in RRA

Simon Hobson linux at thehobsons.co.uk
Mon Nov 3 11:17:19 CET 2008

jan-terje.larsen at telenor.com wrote:

>  > Data time window normalisation.

>OK. I think I see. I have also "ignored" the importance of the start 
>time of the RRD upon creation I guess.
>Those two samples above have the times 10:30:00 and 11:00:00, but I 
>run the polling scripts at 10:10:00 and 10:40:00.
>Are my asumption correct ? That the start time is crucial and must 
>be taken into account when you set the actual polling times ?

No. The sample periods are ALWAYS an integer multiple of step size 
since unix epoch (midnight, 1st Jan 1970). So if you have a step time 
of 1800 (1/2 hour), then sample periods will always start on the hour 
or half hour irrespective of what you use as the start time.

Try Alex's tutorial at http://oss.oetiker.ch/rrdtool/tut/rrdtutorial.en.html

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
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