A thought experiment on Quantum Mechanics and Distributed Failure Detection

One of the biggest problems in current distributed systems is that presented by one machine attempting to determine the liveness of another in a timely manner. Unfortunately, the symptoms exhibited by a failed machine can also be the result of other causes, e.g., an overloaded machine or network which drops messages, making it impossible to detect a machine failure with cetainty until that machine recovers. This is a well understood problem and one which has led to a large body of research into failure suspectors: since it is not possible to detect a failure, the best one can do is suspect a failure and program accordingly. However, one machine's suspicions may not be the same as another's; therefore, these algorithms spend a considerable effort in ensuring a consistent view among all available machines of who is suspects of being failed. This paper describes a thought experiment on how quantum mechanics may be used to provide a failure detector that is guaranteed to give both accurate and instantaneous information about the liveness of machines, no matter the distances involved