On Dependability of Computing Systems

With the rapid development and wide applications of computing systems on which more reliance has been put, a dependable system will be much more important than ever. This paper is first aimed at giving informal but precise definitions characterizing the various attributes of dependability of computing systems and then the importance of (and the relationships among) all the attributes are explained. Dependability is first introduced as a global concept which subsumes the usual attributes of reliability, availability, maintainability, safety and security. The basic definitions given here are then commended and supplemented by detailed material and additional explanations in the subsequent sections. The presentation has been structured as follows so as to attract the reader's attention to the important attributions of dependability. • Search for a few number of concise concepts enabling the dependability attributes to be expressed as clearly as possible. • Use of terms which are identical or as close as possible to those commonly used nowadays. This paper is also intended to provoke people's interest in designing a dependable computing system.