[rrd-users] graph step boundary selection algorithm

Simon Hobson linux at thehobsons.co.uk
Mon Jun 18 12:57:58 CEST 2012

Rafal Gwizdala wrote:

>But for step size equal to 6 hours rrdtool makes the step begin at 
>2AM, 8AM, 2PM and 8 PM instead of 12AM, 6AM, 12PM and 6PM - so 
>there's an overlap between days.

You are in +2 timezone, so 0-6 UTC is shown as 2-8 local, 6-12 UTC is 
shown as 8-14 local, and so on.
RRD only works in UTC, and *ALL* steps/consolidations start/end on an 
integer multiple of the period since unix epoch (midnight 1st Jan 

Simon Hobson

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