The computer-related risk of the year: distributed control

Abstract

The risks inherent in distributed systems with respect to requirements such as security, reliability, availability, real-time performance, and safety are discussed. The risks are seen to be generally no less than, and in many cases greater than, comparable risks in systems with centralized control. The October 27, 1980, Arpanet collapse and the January 15, 1990, AT&T slowdown are presented in order to illustrate some of the serious risks in distributed control. A multiple-copy problem in sendmail is also presented to demonstrate further difficulties in enforcing global consistency. The relative effectiveness of various measures for countering these risks is discussed.<>