[rrd-users] Two graphs with the same scale?

[Sam Rowe]

Hi,

I'm trying to create two graphs with exactly the same scale and I'm
having trouble.

I create the first graph like so:

/usr/bin/rrdtool graph ./graphs/sam-0-c.png --only-graph -i -E -N -M -Y \
   -s 1178020825 -e 1178024425 (...)

and I have some PRINT statements that print the max value for each line
in the graph. I then take the highest of those values, multiply it by
1.1 and use it as the upper limit to create my other graph like so:

/usr/bin/rrdtool graph ./graphs/sam-0-l.png --only-graph -i -E -N -M -Y \
   -s 1178017225 -e 1178020825 \  --rigid --upper-limit 8.107 \
   --lower-limit 0 (...)

This seems to work flawlessly unless the upper limit is less than 2. If
the upper limit is less than 2, it seems like some other algorhythm is
used to determine the scale of the graph.

I've looked through rrd_graph.c, but must confess that C is greek to me.

Any help appreciated. Thanks :)

-Sam