Performance analysis of file replication schemes in distributed systems

In distributed systems the efficiency of the network file system is a key performance issue. Replication of files and directories can enhance file system efficiency, but the choice of replication techniques is crucial. This paper studies a number of replication techniques, including remote access, prereplication, weighted voting, and two demand replication schemes: polling and staling. It develops a Markov chain model, which is capable of characterizing properties of file access sequences, including access locality and access bias. The paper compares the replication techniques under three different network file system architectures. The results show that, under reasonable assumptions, demand replication requires fewer file transfers than remote access, especially for files that have a high degree of access locality. Among the demand replication schemes, staling requires fewer auxiliary messages than polling.