Mutual exclusion in partitioned distributed systems

A network partition can break a distributed computing system into groups of isolated nodes. When this occurs, a mutual exclusion mechanism may be required to ensure that isolated groups do not concurrently perform conflicting operations. We study and formalize these mechanisms in three basic scenarios: where there is a single conflicting type of action; where there are two conflicting types, but operations of the same type do not conflict; and where there are two conflicting types, but operations of one type do not conflict among themselves. For each scenario, we present applications that require mutual exclusion (e.g., name servers, termination protocols, concurrency control). In each case, we also present mutual exclusion mechanisms that are more general and that may provide higher reliability than the voting mechanisms that have been proposed as solutions to this problem. Daniel Barbara is a graduate student in the Computer Science Department at Princeton University and expects to receive his Ph.D. Degree by July 1985. He obtained his BS in Electrical Engineering at the Universidad Metropolitana, Caracas, Venezuela in 1975. His research interests are Distributed Systems, Databases and Computer Networks. He is a member of IEEE and ACM. Hector Garcia-Molina is associate professor in the Department of Computer Science at Princeton University, Princeton, New Jersey. His research interests include distributed computing systems and database systems. He received a BS in electrical engineering from the Instituto Tecnologico de Monterrey. Mexico, in 1974. From Stanford University, Stanford, California, he received in 1975 a MS in electrical engineering and a PhD in computer science in 1979. Garcia-Molina is a member of the ACM and IEEE.