Computers are currently used in a variety of critical applications, including systems for nuclear reactor control, flight control (both aircraft and spacecraft), and air traffic control. Moreover, experience has shown that the dependability of such systems is particularly sensitive to that of its software components, both the system software of the embedded computers and the application software they support. Software Performability: From Concepts to Applications addresses the construction and solution of analytic performability models for critical-application software. The book includes a review of general performability concepts along with notions which are peculiar to software performability. Since fault tolerance is widely recognized as a viable means for improving the dependability of computer system (beyond what can be achieved by fault prevention), the examples considered are fault-tolerant software systems that incorporate particular methods of design diversity and fault recovery. Software Performability: From Concepts to Applications will be of direct benefit to both practitioners and researchers in the area of performance and dependability evaluation, fault-tolerant computing, and dependable systems for critical applications. For practitioners, it supplies a basis for defining combined performance-dependability criteria (in the form of objective functions) that can be used to enhance the performability (performance/dependability) of existing software designs. For those with research interests in model-based evaluation, the book provides an analytic framework and a variety of performability modeling examples in an application context of recognized importance. The material contained in this book will both stimulate future research on related topics and, for teaching purposes, serve as a reference text in courses on computer system evaluation, fault-tolerant computing, and dependable high-performance computer systems.

This volume contains the papers presented at the Second International Work ing Conference on Dependable Computing for Critical Applications, sponsored by IFIP Working Group lOA and held in Tucson, Arizona on February 18-20, 1991. In keeping with the first such conference on this topic, which took place at the University of California, Santa Barbara in 1989, this meeting was like wise concerned with an important basic question: Can we rely on Computers? In more precise terms, it addressed various aspects of computer system de pendability, a broad concept defined as th'e trustworthiness of computer service such that reliance can justifiably be placed on this service. Given that this term includes attributes such as reliability, availability, safety, and security, it is our hope that these papers will contribute to further integration of these ideas in the context of critical applications. The program consisted of 20 papers and three panel sessions. The papers were selected from a total of 61 submissions at a November 1990 meeting of the Program Committee in Ann Arbor, Michigan. We were very fortunate to have a broad spectrum of interests represented, with papers in the final program coming from seven different countries, representing work at universities, corporations, and government agencies. The process was greatly facilitated by the diligent work of the Program Committee and the quality of reviews provided by outside referees. In addition to the paper presentations, there were three panel sessions or ganized to examine particular topics in detail."

Computers are currently used in a variety of critical applications, including systems for nuclear reactor control, flight control (both aircraft and spacecraft), and air traffic control. Moreover, experience has shown that the dependability of such systems is particularly sensitive to that of its software components, both the system software of the embedded computers and the application software they support. Software Performability: From Concepts to Applications addresses the construction and solution of analytic performability models for critical-application software. The book includes a review of general performability concepts along with notions which are peculiar to software performability. Since fault tolerance is widely recognized as a viable means for improving the dependability of computer system (beyond what can be achieved by fault prevention), the examples considered are fault-tolerant software systems that incorporate particular methods of design diversity and fault recovery. Software Performability: From Concepts to Applications will be of direct benefit to both practitioners and researchers in the area of performance and dependability evaluation, fault-tolerant computing, and dependable systems for critical applications. For practitioners, it supplies a basis for defining combined performance-dependability criteria (in the form of objective functions) that can be used to enhance the performability (performance/dependability) of existing software designs. For those with research interests in model-based evaluation, the book provides an analytic framework and a variety of performability modeling examples in an application context of recognized importance. The material contained in this book will both stimulate future research on related topics and, for teaching purposes, serve as a reference text in courses on computer system evaluation, fault-tolerant computing, and dependable high-performance computer systems.