Autonomy and interdependence in the DUNIX system

This paper discusses the balance between autonomy and interdependence in the design of the DUNIX distributed operation system. DUNIX is a UNIX like timesharing system for a moderate community of users who are willing to share resources. The hardware controlled by DUNIX is composed of several computers connected by a packet-switching-network. Each computer has its own peripheral devices. The majority of the disks are dual ported to two computers, but at any instant, only one of these two ports is enabled. DUNIX uses this hardware to create an illusion. It makes the users and their software believe that the system is single large computer running UNIX. The illusion is so complete that the DUNIX kernels are able to migrate any running process from one computer to another without disturbing the behavior of the process.The goals of DUNIX were: ease of use, high availability, smooth, incremental growth, ease of maintenance, and ease of providing new (and yet unseen) services. To clarify, the following were not the goals of DUNIX. It is not a new way to build a supercomputer. It is not a real-time, or data-base, or fault-tolerant system. It is not for personal-computers (or workstations), and it is not scalable. More information on DUNIX may be found in: A. Litman, The D UNIX Distributed Operating System, Operating Systems Review, January 1988.The term 'autonomous' has two aspects: self-contained and self-controlled. The first means: capable to function all by itself. The second means: does not blindly follow external instruction. We will discuss the balance between these two aspects and interdependence separately.