Implementable Failure Detectors in Asynchronous Systems

Failure detection is one of the most fundamental modules of any fault-tolerant distributed system. The failure detectors discussed in the literature so far are either impossible to implement in an asynchronous system, or their exact guarantees have not been discussed. We introduce a failure detector called innnitely often accurate failure detector which can be implemented in an asynchronous system. We provide one such implementation and show its application to the fault-tolerant server maintenance problem. We also show that some natural timeout based failure detectors implemented on Unix are not suucient to guarantee innnitely often accuracy.