[rrd-users] Diurnal average

[Alex van den Bogaerdt]

>> Over how many days ?
>
> Over the entire database (2 years).
> Yes, using time shift may work, but it's not really flexible when I want
> to change parameters.

Not just that. If it's 2 years worth of data, this means 730 or so days
with evenso number of DEFs. You may run into performance problems or even
limits. Perhaps it just won't fit in a script (hint: pipe mode may still
work).

First of all make sure you have those 2 years in the resolution required
("standard" examples speak of 2 years, but only part of it is hi-res).

Then, perhaps you can generate your numbers using rrdtool in pipe mode,
xport each day, and process the results outside rrdtool using e.g. perl?

Another possible unexpected detail: depending on where you live, you may
find that you are adding up different "wall clock" times. Make sure you
understand timezones and daylight saving / summer time.