Availability evaluation of redundant computer systems

This paper investigates availability of two redundant computer systems, a duplex system and a load share system, under the assumptions that the failure time distribution is bivariate exponential and the repair time distribution is arbitrary. We derive the limiting availability for each system by applying a unique modification of regeneration point techniques in Markov renewal processes. In particular, the procedure for obtaining the limiting probability is presented thoroughly. This paper also gives numerical examples for comparison of the two systems from the viewpoint of the availability.