Stochastic Modeling and Availability Evaluation of Computer Systems

Abstract

There are many applications of the computer systems where in the system availability has to be ensured. The evaluation of the availability is very vital before a computer system is being put into operation in such critical applications. In the case of hardware faults, high degree of reliability can be achieved by hardware redundancy. For microprocessor systems good additional feature is fault tolerance. By the use of dedicated customized hardware, fault tolerance can be achieved which is cost effective. A stochastic modeling of the microprocessor based computer system has been carried out and the lifetime availability is estimated. This evaluation is always being during the entire process of system design. The modeling framework used for the Multiprocessor system is based on an extension of Petri nets called Stochastic Activity Networks (SAN). A major contribution of this paper is that a SAN based comprehensive model for computer system using Mobius simulation tool has been developed which can be extensively used for the lifetime evaluation of systems of various architectures and hardware designs.