Well, duh! I didn't know Hobbit/rrdtool did that!

["Haertig, David F (Dave)" <haertig (at) avaya.com>]

After messing around and messing around trying to set graph timeframes
and vertical axis limits, I just had a duh! moment.  You don't need
that.
 
Those little magnifying glass icons?  Yeah, I had clicked on them before
expecting to zoom in on the graph.  But it never zoomed in ... it just
showed the same graph again on a seperate webpage.  I figured it was
some broken feature.  My duh! moment just came when I accidently drug my
mouse cursor over part of the "non zoomed" graph and noticed, "Hey! I
wonder why it highlighted only that small portion of the graph?!"
Release the mouse button and it becomes very evident why.  DUH!!!
 
How is it possible for me to have been so stupid?!    :-o