Optimal replication transition strategy in distributed hierarchical systems

We study the replication transition problem in distributed hierarchical systems. Most distributed systems replicate data to increase data access efficiency. A replication strategy dictates where the replicas are stored in respond to the data access pattern, therefore a good strategy can effectively improve data access efficiency. However, the access pattern in a distributed system is constantly changing. As a result, a good replication strategy must evolve accordingly. The replication transition problem is to seek an efficient transition from one replication strategy to another, in order to cope with the dynamic access pattern. This paper focuses on solving the replication transition problem on tree topology, which is one of the most important models in data grid systems and Web proxy systems from the literature. To the best of our knowledge, our work is the first that proposes an optimal algorithm for the replication transition problem on tree topology. The algorithm has a time complexity of O(n log Deltalog(nLambda)), where n is the number of sites, Delta is the maximum degree in the tree and Lambda is the largest communication delay in the network.