Replication Methods and Their Properties

Abstract

The most important evaluation criteria for replication methods are availability, performance, consistency, and costs. Performance and response time may be improved by substituting remote data accesses with local data accesses to replicated data. The availability of the system can be increased by using replicated data in case a local failure or disaster should occur. The major disadvantages of data replication are the additional costs of updating replicated data and the problems related to managing the consistency of the replicated data. Tables 1 and 2 give an overview of the evaluation of the replication methods described in this article. Frank (1999) described how such replication overviews may be used to optimize databases in practice. This article evaluates many more replication methods and therefore, it is possible to optimize even more. However, the evaluation criteria previously described have to be subdivided to illustrate the different properties of the different replication methods.