Zyzzyva: Speculative Byzantine Fault Tolerance
A longstanding vision in distributed systems is to build reliable systems from unreliable components. An enticing formulation of this vision is Byzantine fault-tolerant (BFT) state machine replication, in which a group of servers collectively act as a correct server even if some of the servers misbehave or malfunction in arbitrary ("Byzantine") ways. Despite this promise, practitioners hesitate to deploy BFT systems at least partly because of the perception that BFT must impose high overheads.
