Berkeley UNIX on 1000 Workstations: Athena Changes to 4.3BSD

4.3BSD UNIX as shipped is designed for use on individually-managed, networked timesharing systems. A large network of individual workstations and server machines, all managed centrally, has many important differences from such a model. This paper discusses some of the changes necessary for 4.3 in this new world, including the file system layout, configuration files, and software. The integration with Athena's authentica-tion system, name service, and service management system are also discussed. 1. Overview ''By 1988, create a new educational computing environment environment at MIT built around high-performance graphics workstations, high-speed networking, and servers of various types.'' This one-sentence statement is a high-level description of the technical goals of Project Athena. While the primary goals are to enhance education, attaining them has required a significant effort to engineer a software environment for use in a large network of workstations and servers. The Athena hardware environment currently consists of approximately 650 workstations and 65 dedicated server machines. There are two kinds of workstations: DEC Micro-VAX systems and IBM RT PC's. The servers are VAX 11/750's or dedicated workstations of either type. The operating system in use now is 4.3BSD UNIX on the VAX machines, and IBM's 4.3/RT UNIX for the RT PC systems. All systems include support for Sun Microsystem's Network File System (NFS). 1 The workstations and servers are connected to local-area Ethernet subnetworks, which are linked by a high-speed fiber optic † UNIX is a Trademark of Bell Laboratories. ''spine.'' At present, there are twelve such sub-networks. The problems of a distributed system are the scale of the operation and the role of the network as a fundamental component. UNIX systems have traditionally been managed on a ''one system , one wizard'' basis, but this is not acceptable at an eventual scale of 1000 workstations, 100 server machines, and 10,000 users. Two questions often asked are: ''Does it scale?'' and ''Is it well-behaved on the network?'' All too often, the answer to one or the other is ''No,'' and part of the system must be reworked to satisfy those constraints. This paper describes the goals and constraints faced by Athena, as well as many of the solutions devised in building such a system. In particular, the next two sections examine the goals and evolution of the computing system side of the Project. Next is a discussion of the base operating systems in use, such as 4.3BSD. This is followed by …