I got what you meant by having one hard drive and one SBC used as the "server" or main interfacing computer. But I thought that routers were only used for internet, and what exactly is a switch when it comes to talking about multiple SBCs?
From reading that article I figured out that an single board computer
doesn't involve a motherboard, but that it's typically a smaller more miniature version of one with all the parts, that is then plugged into a backplane, which is from what I can tell basically a powered circuit main board that provides power to all the plugged in "cards" or SBCs, that would be hooked up to it. Do I understand the concept correctly?