A History of the Virtual Synchrony Replication Model

In this chapter, we discuss a widely used fault-tolerant data replication model called virtual synchrony. The model responds to two kinds of needs. First, there is the practical question of how best to embed replication into distributed systems. Virtual synchrony defines dynamic process groups that have self-managed membership. Applications can join or leave groups at will: a process group is almost like a replicated variable that lives in the network. The second need relates to performance. Although state machine replication is relatively easy to understand, protocols that implement state machine replication in the standard manner are too slow to be useful in demanding settings, and are hard to deploy in very large data centers of the sort seen in today’s cloud-computing environments. Virtual synchrony implementations, in contrast, are able to deliver updates at the same data rates (and with the same low latencies) as IP multicast: the fast (but unreliable) Internet multicast proto...

• Type: Journal
• Year: 2010
• Where: REPLICATION
• Authors: Ken Birman
• Keywords: Computational Biology, REPLICATION 2010, State Machine, State Machine Replication, Virtual Synchrony