[rrd-users] Re: Daily statistics - midnight local vs UTC

[Alex van den Bogaerdt]

On Sat, Nov 11, 2006 at 09:28:45AM -0600, Larkin Lowrey wrote:

> Hello, I am trying to record daily averages and am running into a
> problem where rrdtool thinks that the day begins at midnight UTC instead
> of midnight localtime (CST). I remember encountering this problem
> several years ago but can't remember the solution.

> I'm a bit surprised this is still an open issue.

There isn't an issue.  It is documented behaviour and rrdtool is doing
what you ask it to do.

> What is the magic trick?

If you want data to start and end on something else than n*86400,
you need RRAs covering something else than 86400 seconds per row.

> Here's what I used to create the database.
> 
> rrdtool create mailstats.rrd \
>         --step 3600 \
>         DS:rejected:COUNTER:7200:U:U \
>         DS:spam:COUNTER:7200:U:U \
>         DS:passed:COUNTER:7200:U:U \
>         RRA:AVERAGE:0.5:1:744 \

{n-1}*3600 to {n}*3600, for example n==322926:
a slot starting at 1162530000 and ending at 1162533600
(23:00 to 24:00 your local time I believe)

This means you can do:  start=end-24h end=1162533600
RRDtool should select the 24 hours making up your local day,
provided of course that the data is available.


>         RRA:AVERAGE:0.5:24:730 \

{n-1}*24*3600 to {n}*24*3600, for example n==13456:
a slot starting at 1162512000 and ending at 1162598400

This RRA does not have a timeslot ending at 1162533600
because 1162533600 is not n*86400 (n is an integer number).

-- 
Alex van den Bogaerdt
http://www.vandenbogaerdt.nl/rrdtool/

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