Created Wednesday 03 July 2019
This is probably the easiest concept to understand as that's how we think about the world. Each server operates in it's own private physical server with dedicated hardware and operating system. This is obviously the most physical and probably the greatest cost, but the experience of having a physical device doing one dedicated function is the foundation of computer networks. My preference is to have one server performing one function, although one server would be more than capable of handling concurrent instances of different programs. Physical isolation requires that the servers have to be configured correctly so that they communicate across the network, which is another level of knowledge to be acquired.
If you want to go this route, you will need a physical server for each major function, appropriate networking hardware, network cables, and enough power to run the physical equipment. You will probably need shelving and a space to set up all of the equipment so that it is neat and organized.
The servers, in this instance, don't need to be anything fancy. The same situation exists where there is only one or two users operating the servers, so nothing powerful is required. Any old equipment can perform the role of a server, whether it is a collection of old laptops, discarded desktops, or even several Raspberry Pi.
You will need enough network ports to connect each of the servers, plus some extra room for future expansion. Again, speed isn't that important because you won't be transferring large amounts of data across the network.
In this instance, seven or eight servers plus a small network switch would be more than enough to deal with