Originally Posted by till
If the first server shall provide only the controlpanel and no services, then you you dont have to install all services on it. For a controlpanel only server you need just mysql, php and apache and fail2ban.
Ok, I think I'm getting the basic idea. You install the services and then use ispconfig to configure them. There are 2 options for a server: Being stand-alone and being a slave to some other server.
When a server is a slave it mirrors data from it's master (as in DNS primary/secondary server). A slave webserver can be used to HA using haproxy or some other cache (varnish etc).
When a server is a master, it can be used to install a site for a domain, host a mailserver (postfix+dovecot) and so on.
I have another question regarding DNS service. Looking at a minimal setup of 2 servers (bare metal with no VM installed) I envision the need to run all services on both servers, where one of them will be running also the ispconfig web interface, while DNS will be shared.
I agree that the above setup is less than optimal and that a better setup would be using openvz containers to isolate different services talking to each other on a private network while exposing only the bare services outside on a public network.