The Costs and Limits of Availability for Replicated Services

As raw system and network performance continues to improve at exponential rates, the utility of many services is increasingly limited by availability rather than performance. A key approach to improving availability involves replicating the service across multiple, wide-area sites. However, replication introduces well-known tradeo s between service consistency and availability. Thus, this paper explores the bene ts of dynamically trading consistency for availability using a continuous consistency model. In this model, applications specify a maximum deviation from strong consistency on a per-replica basis. In this paper, we: i evaluate availability of a prototype replication system running across the Internet as a function of consistency level, consistency protocol, and failure characteristics, ii demonstrate that simple optimizations to existing consistency protocols result in signi cant availability improvements more than an order of magnitude in some scenarios, iii use our expe...

• Type: Conference
• Year: 2001
• Where: SOSP
• Authors: Haifeng Yu, Amin Vahdat
• Keywords: Consistency Protocols, Continuous Consistency Model, Operating System, SOSP 2001, Strong Consistency