Using dynamic replication to manage service availability in a multimedia server cluster

Abstract

Dynamic replication policies assign non-disjoint subsets of multimedia presentations to nodes in a server cluster, replicating selected presentations to achieve load-balancing, while avoiding complete replication of the multimedia archive on every node. This paper presents a development of our existing Dynamic RePacking policy, which creates a configurable minimum number of replicas of selected presentations, increasing their availability. These additional replicas are assigned to nodes in a manner that allows load-balancing to be maintained when nodes fail. By separating replication to achieve load-balancing from replication to increase the availability of individual presentations, the trade-off between availability and storage cost can be controlled. This is illustrated by performance results from a prototype multimedia server cluster, which uses a group-communication service to implement inter-node communication. © Springer-Verlag 2004.