[rrd-users] Re: Possible problem with daylight savings.

[Alex van den Bogaerdt]

On Mon, Apr 28, 2003 at 03:13:01PM -0400, Jon Nistor wrote:

> Wondering if anyone else has run into this problem or not, I can't seem to
> find any references to it in the archives either.
> The graph in question is attached (graph.gif).  Its a monthly output of
> some bw usage for a host.  If you notice, the day portions for everything
> after mid-week14 start showing the redline for midnight.
> 
> ref:
> 	CDEF:day00=gfh,POP,LTIME,86400,%,0,EQ,INF,UNKN,IF \
>         AREA:day00#FF0000:"   Midnight / 00\:00 to 00\:05 ( First 300 seconds )\n" \

LTIME is the epoch time corrected for the time zone.  The offset from
utc changed and the behaviour changed.  That's no coincidence.

> If I'm not mistaken mid-week14 is when the timechange for us was (in
> EST5EDT).

You're graphing something from an RRA with a 2-hour resolution, right?

During normal time the intervals are:
01:00 to 03:00, 03:00 to 05:00 ... 21:00 to 23:00, 23:00 to 01:00

During DST the intervals are:
02:00 to 04:00, 04:00 to 06:00 ... 22:00 to 00:00, 00:00 to 02:00

Et voila, there's your midnight occuring.

HTH
Alex
-- 
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