A List-Based Strategy for Optimal Replica Placement in Data Grid Systems

Data replications is a typical strategy for improving access performance and data availability in data grid systems. Current works on data replication in grid systems focus on the infrastructure for data replication and the mechanism of replicas creation and deletion.The important problem of choosing suitable locations for placing replicas in data grids has not been fully studied. This paper addresses replica placement problem in data grids when given a sequence of priority lists that specify the forwarding policies for data requests. We propose the concept of priority list to address two issues. First, a user may have limited authority in accessing the resources, and thus his/her data requests should be prohibited from accessing some of the sites. Second, a static policy may not satisfy a data request with special requirements (e.g. quality of service requirement). In this priority-list-based model we propose a placement algorithm that finds optimal locations for replicas so that the workload among the replicas is balanced. We also propose an algorithm that determines the minimum number of replicas when the maximum workload capacity of each replica is given.