Optimal Replica Placement in Data Grid Environments with Locality Assurance

Data replication is typically used to improve access performance and data availability in Data Grid systems. To date, research on data replication in Grid systems has focused on infrastructures for replication and mechanisms for creating/deleting replicas. The important problem of choosing suitable locations to place replicas in Data Grids has not been well studied. In this paper, we address three issues concerning data replica placement in Data Grids. The first is how to ensure load balance among replicas. To achieve this, we propose a placement algorithm that finds the optimal locations for replicas so that their workload is balanced. The second issue is how to minimize the number of replicas. To solve this problem, we propose an algorithm that determines the minimum number of replicas required when the maximum workload capacity of each replica server is known. Finally, we address the issue of service quality by proposing a new model in which each request must be given a quality-of-service guarantee. We describe new algorithms that ensure both workload balance and quality of service simultaneously.