Several properties, such as safety, reliability, and availability, are commonly desired of large contemporary systems. Safety, “the condition of being protected from or unlikely to cause danger, risk, or injury,” is related to the property of reliability, “the characteristic of an item expressed by the probability that it will perform its required function in the specified manner over a given time period and under specified or assumed conditions.” Safety and reliability overlap, but are not identical; for any reasonable characterization of the two, the set of systems that are safe and the set of systems that are reliable have a nonempty intersection, but are not the same. Similarly, system availability is related to system reliability, but the qualities differ.

This book is a collection of 11 chapters and five appendices that contain a treatment of some of the basic concepts of system availability and system reliability, particularly as they relate to computing and network systems. Chapter 1 is a one-page introduction, with a couple more pages that give a brief description of the chapters to follow. Chapter 2, “System Availability,” is a brief introduction to some basic concepts in reliability analysis, such as mean time to failure (MTTF), with a special focus on the TL 9000 standard. The next three chapters cover specific availability issues, such as why availability varies between customers. Chapters 6 to 8 deal with the estimation of parameters from field data, lab data, and during design. Chapter 9 discusses the accuracy of system predictions. Chapter 10, “Connecting the Dots,” attempts to briefly fill in some of the details necessary to relate some of the concepts presented to real systems. Chapter 11 is a summary that offers less than a page of concluding remarks. The appendices give some background information, such as prerequisite mathematical concepts, acronyms, and a bibliography.

Contrary to what the title implies, there is virtually no discussion of noncomputing systems (such as classical industrial equipment); a better title would have been Network system reliability, also because telecommunications-specific matters such as the TL 9000 standard are mentioned at some length. Sure, there are many parallels between classical industrial systems and contemporary information technology (IT) systems [1], but it would be a mistake to conflate IT or telecommunications systems with all systems. It is also ironic that chapters 2 to 6 are devoted to availability, while there is little discussion of reliability; as the authors themselves note on page 7, “availability and reliability are often confused, partly because the term reliability tends to be used when availability is what was really intended.” Also, somewhat at odds with what the title suggests, the book is really a basic introduction to some of the concepts necessary to understand reliability or availability, and would not suffice to handle the complexities associated with real systems, especially those that do not relate to telecommunications.

In general, the depth and breadth of this book’s presentation are probably not sufficient even for a practitioner (and much less so for a theoretician); other texts would also have to be consulted, such as Rausand and Høyland’s much more comprehensive classic [2].