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Minimizing Cost of K-Replica in Hierarchical Data Grid Environment

Replicating of objects at multi nodes has been considered a promising technique for decreasing access cost and network traffic for a large distributed systems like Data Grids. In this paper we propose Optimal Placement of Replicas (OPR) algorithm with the objective of minimizing the total replication cost including communication and storage cost, given that a maximum of k replicas are allowed in a tree data grid with n nodes and height h. OPR has time complexity of O(nhk), which is the lowest time complexity compared with the other algorithms with the same objective function in the past literature. In addition, two greedy algorithms, namely, Greedy Algorithm (GA) and Simple Greedy Algorithm (SGA) are proposed for near optimal placement of k replicas with the lower time complexity compared with that of OPR. We evaluate the proposed algorithms through an extensive simulation experiments in terms of access cost, network traffic and locality access to objects.