[rrd-users] water usage

A Darren Dunham ddunham at taos.com
Fri Jul 23 19:17:00 CEST 2010

On Thu, Jul 22, 2010 at 08:19:10PM -0400, Rick Dicaire wrote:
> On Thu, Jul 22, 2010 at 7:51 PM, A Darren Dunham <ddunham at taos.com> wrote:
> > But you haven't said anything about your data or how you're putting it
> > into the RRD.
> I've run into other problems.
> rrdtool create /backup/mrtg-2/mrtg/rrd/water.rrd \
> --step '86400' \


> rrdtool updatev /backup/mrtg-2/mrtg/rrd/water.rrd 1279641600:140
> 1279728000:750 1279814400:190

And this^^^

Are causing most of your problems.  RRD steps are always on even "step"
multiples of "epoch" time.  So in other words, your bins are in GMT/UTC
days, not localtime days.  You can't shift them to line up.

Meanwhile your update is using the start of the localtime day.  That
gets normalized into both bins, not consolidated into one bin.

If you want to go this route, you may have better luck running
everything in TZ=UTC, and putting the updates at the beginning of the
UTC day.

Replace your update line with this:
#rrdtool updatev water.rrd 1279641600:140 1279728000:750 1279814400:190
rrdtool updatev water.rrd 1279670400:140 1279756800:750 1279843200:190

and see how the graph changes.

An alternative is to not use "day" steps, but "hour" steps, and leave
long heartbeats.

'RRA:LAST:0.01:1:900' \
rrdtool updatev water.rrd 1279641600:140 1279728000:750 1279814400:190

Make either of those changes and your graph should improve.


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