Peer Replication with Selective Control

Abstract

Many mobile environments require optimistic replication for improved performance and reliability. Peer-to-peer replication strategies provide advantages over traditional client-server models by enabling any-to-any communication. These advantages are especially useful in mobile environments, when communicating with close peers can be cheaper than communicating with a distant server. However, most peer solutions require that all replicas store the entire replication unit. Such strategies are inefficient and expensive, forcing users to store unneeded data and to spend scarce resources maintaining consistency on that data.We have developed a set of algorithms and controls that implement selective replication, the ability to independently replicate individual portions of the large replication unit. We present a description of the algorithms and their implementation, as well as a performance analysis. We argue that these methods permit the practical use of peer optimistic replication.