[rrd-users] Strange behavior when using CDEF to divide twovalues

Tue Feb 19 00:26:41 CET 2013

> I applied that to all three graphs, but unfortunately that didn't change 
> the result. I also changed the CF on de RRA from AVERAGE to MAX but that 
> also didn't change the result.
> The new graphs are now available here: http://ernstagn.home.xs4all.nl/rrd/
>
> Any suggestions ?

Let's zoom in to see what happens.
Please, create an index.html file containing those three images, it's easier 
to see what's going on that way.
html purists won't like it, but it works:
<head><base href="http://ernstagn.home.xs4all.nl/rrd/"></head>
<body>
<img src="length.png"><br>
<img src="number.png"><br>
<img src="avg.png"><br>
</body>

Then graph from mon 06:00 to 10:00. 4 hours, should be 48 times 300 seconds. 
Set the image width to 480 pixels.
I expect to see images that jump from rate to rate every 10 pixels.
Provide the output of an rrdtool dump, but please only the relevant parts 
(again: 06:00 to 10:00)
Add some output to your graphs. min, avg and max.

To make it easier for others to help you debug, you could write a small 
script that:
a) creates a database
b) updates the database with those 48 value/timestamp combinations (no 
"N:50", but e.g. "1361163900:50")
c) creates the graphs

Let's tackle this problem :) 