[rrd-users] Bar graph by hour, day, month
Alex van den Bogaerdt
alex at vandenbogaerdt.nl
Tue Sep 30 00:17:20 CEST 2014
----- Original Message -----
From: <bsuarez at free.fr>
To: "Simon Hobson" <linux at thehobsons.co.uk>
Cc: <rrd-users at lists.oetiker.ch>
Sent: Monday, September 29, 2014 4:07 PM
Subject: Re: [rrd-users] Bar graph by hour, day, month
> My water meter delivers one pulse per liter consumed. I have a script that
> counts the pulses (raspberry and piface).
> Periodically I want to store in the RRD database the number of pulses.
> The first solution is to periodically store the number of impusions since
> the last backup.
> The second solution is to periodically store the total impusions since the
> start of counting
There may be another solution:
Don't store and count. Just feed to RRDtool as soon as a pulse comes in.
Your counter type would still be ABSOLUTE, you would feed number 1 (1
liter). No need to remember anything, except that it would be wise to create
an idle timer. If no pulses are generated for 24 hours (or any other
suitable number), then feed number 0 to RRDtool and reset the idle timer.
(and, of course, don't forget to set the timeout value in your database to
an appropriate value, larger than 24 hours or the number you chose).
> For graphs, displaying data on last 5 minutes, last hour, last day, last
> month should be enough.
What Simon tried to explain to you, is that "last month" is tricky. You
probably expect to get columns for each day. If you are aware how RRDtool
works (by design) and if you do not mind seeing days which start at midnight
UTC, then no problem.
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