Ten Fallacies of Availability and Reliability Analysis

As modern society becomes more and more dependent on computers and computer networks, vulnerability and downtime of these systems will significantly impact daily life from both social and economic point of view. Words like reliability and downtime are frequently heard on radio and television and read in newspapers and magazines. Thus reliability and availability have become popular terms. However, even professionals are in the danger of misunderstanding these basic concepts. Such misunderstandings can hinder advances in designing and deploying high-availability and high-reliability systems. This paper delves into ten fallacious yet popular notions in availability and reliability. While the discussions on the first five fallacies clarify some misconceptions among reliability engineers working on modeling and analysis, the remaining five fallacies provide important insights to system engineers and companies focusing on system level integration.