Scaling-Zoom

[Sanders]

Please help to change displaying.
For example graph with preset "Last 4 Hours":

That's correct displaying.

But when I just change to preset "Last 6 Hours":

It looks rude.

How can I change this displaying ?
How to make the graph looks normal when the period is extended?

[netniV]

This is normal, by changing the time period you have switched to a more averaged view which uses a slightly different data set. It's the way rrdtool works, you should research that.