How to bring up an hourly graph for a specified period (rather than only "Last Hour") in Ganglia
The Ganglia web version that ships with your distribution doesn't have this feature. You have to show the graphs in last day and zoom in to an area of interest.
However, you can do it by using the ganglia-web version from the homepage:
Also, don't miss some important other features like: Aggregate graphs, Compare Host, ... See document fore more details.