ABSTRACT
The first drawback can be illustrated with a simple system of two components connected in parallel. In order for the system to fail, both componentsmust fail. Which one is to blame? The answer is of course both of them. If the stationary availabilities of the components are given by p1 = 0.9 and p2 = 0.1, respectively, we have the system availability 1 − (1 − p1)(1 − p2) = 1 − 0.09 = 0.91.
