Availability and Consistency of Global Information in Computer Networks

摘要

A principal feature of computer networks is the ability of the various sites of the network to access and update shared information. At the application level, the global information takes the form of shared file systems, databases, etc., and at lower levels, it takes the form of status information used in controlling the network. This research focused techniques for maintaining the availability of global information in the face of various kinds of failures and the consistency of global information in the presence of concurrency. Two failure models were considered: the crash model, in which failures are instantly detected, and the malfunction model, in which an indefinite period of time may lapse before failures are detected. A network status maintenance scheme based on a global clock facility was designed for the crash model. For the malfunction model, an approach to maintaining the correctness of global information and preventing error propagation was developed. Centralized and distributed deadlock detection algorithms were developed for distributed databases. (Author)