Let's start with a few basic terms and concepts, so that everyone is starting out on the same level. The most important is the term cluster, which when mentioned herein refers to a group of individual computers bundled together using hardware and software in order to make them work as a single machine.
Each individual machine of a cluster is referred to as a node. Within the OSCAR cluster to be installed, there are two types of nodes: server and client. A server node is responsible for servicing the requests of client nodes. A client node is dedicated to computation.
An OSCAR cluster consists of one server node and one or more client nodes, where all the client nodes [currently] must have homogeneous hardware. The software contained within OSCAR does support doing multiple cluster installs from the same server, but no documentation is provided on how to do so.