[rrd-users] Consolidating to a Daily RRA

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Wed Mar 5 18:17:28 CET 2014

The question has come up before, but I have to admit I do not know if there 
is anything implemented right now.  My guess is that it is not as easy to do 
as it sounds, especially because it would probably introduce bugs, some of 
them very obscure.

Every timestamp used everywhere would need this offset applied.  If you can 
spare the hardware, why not run this RRDtool setup on it's own dedicated box 
which happens to have it's internal clock set deliberately wrong. Let the 
machine think it is running on british time (if you want DST corrected) or 
on icelandic time (if you want UTC all the time), adjust the clock so that 
wall clock time matches your local time, and you should be ready.

Time synchronization will be a challenge but still not impossible.

It's just a thought, my 2ct, et cetera.

----- Original Message ----- 
From: <nhoeller at sinet.ca>
To: <rrd-users at lists.oetiker.ch>
Sent: Wednesday, March 05, 2014 5:32 PM
Subject: [rrd-users] Consolidating to a Daily RRA

>I have been using rrdtool to capture and consolidate solar radiance,
> temperature and production from a solar array.  The ability of rrdtool to
> work with large volumes of information at different granularity has been
> very useful.  Perhaps even more important has been gaining an
> understanding of the issues around data quality and the details of
> consolidation.
> One issue has been the daily consolidation.  I understand the benefits of
> working in UTC and using midnight UTC as the daily roll-over time.
> However, it turns out that in my case roll-over occurs at 19:00 EST or
> 20:00 EDT which means early evening data sometimes gets moved to the next
> day.
> I understand the challenges of using local midnight.  I have also reviewed
> some of the workarounds including using a local timestamp (this will cause
> issues if I want to create graphs) and exporting hourly data into another
> 'daily' rrd (significantly larger primary rrd).  Would adding an option
> that allows us to configure an offset from UTC for the typical 'end of
> day' be useful and easily implementable?  For my purposes, I can work in
> EST and ignore Daylight Savings.
>        Thanks, Norbert


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