Fault tolerance in embedded real-time systems: importance and treatment of common mode failures

Dependable computer architectures used in critical embedded real-time applications have successfully employed Byzantine resilience techniques to tolerate physical, internal, operational faults. The dominant cause of failure of a correctly designed Byzantine resilient computer today is the common-mode failure, i.e., the nearly simultaneously failure of multiple redundant copies, generally due to a single cause. Unlike independent hardware faults, for which theoretically rigorous fault tolerance solutions have been implemented, the sources of common-mode failures are so diverse that numerous disparate techniques are required to predict, avoid, remove, and tolerate them.