State machine replication is a common approach for building fault-tolerant services. A Replicated State Machine (RSM) typically uses a consensus protocol such as Paxos to decide on the order of updates and thus keep replicas consistent. Using Paxos, the RSM can continue to process new requests, as long as more than half of the replicas remain operational. If this bound is violated, however, the current RSM is forced to stop making progress indefinitely. To avoid scenarios in which the number of failures exceeds the bound, it is beneficial to immediately instantiate failure handling, if this can be done without causing a significant disruption to request execution.
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