A cluster usually consists of:
-  a group of compute host machines, and
 -  a cluster server used for the following purposes:
- a file server for SCore cluster administration
the Cluster Database Server, scoreboard, and
the Compute Host Lock Server, msgbserv are running
on this computer
 - software development compilation 
 - running cluster maintenance daemons
 
 
For instance, if you want to build a cluster of 8 compute hosts,
you need to buy 9 computers.
Though we recommend having a cluster server,
you may install software for the cluster server onto one of the compute hosts,
so that you don't need to buy a computer for the server.
A router is also necessary if you plan to connect the cluster to a LAN. 
All processor hosts forming a homogeneous cluster should be of the same
architecture and use the same version of the operating system.