Distributed computer systems: Four case studies

Distributed computer applications built from off-the-shelf hard-ware and software are increasingly common. This paper examines four such distributed systems with contrasting degrees of decentralized hardware, control, and redundancy. The first is a one-site system, the second is a node-replicated system at a remote site for disaster backup, the third is a multi-site system with central control, and the fourth is a multi-site system with node autonomy. The application, design rationale, and experience of each of these systems are briefly sketched.