The main page of Virtualmin website shows a graph of system statistics, but I could not find it. How I can see this graph?
And is it possible to monitor concurrent Apache processes (i.e. visitors)?
Howdy,
There are indeed some nice graphs, but those are part of the Pro version of Virtualmin 
As far as monitoring visitors – Virtualmin (both Pro and GPL) typically sets up Webalizer for each domain that’s setup. You can access the Webalizer statistics by browsing to yourdomain.tld/stats/.
-Eric
Yup, me too
That graph is part of a set of graphing/statistics options that are available in Virtualmin Pro.
If you want to see more, you can always try out the Virtualmin Pro demo, using the “Demo” link at the top of the page.
-Eric