Reliability block diagram

Parallel blocks indicate redundant subsystems or components that contribute to a lower failure rate.

If a path may be found through the network of switches from beginning to end, the system still works.

To evaluate an RBD, closed form solutions are available when blocks or components have statistical independence.

When statistical independence is not satisfied, specific formalisms and solution tools such as dynamic RBD have to be considered.

μ >> λ If the components in a parallel system have n different failure rates a more general formula can be used as follows.