An empirical comparative study of decentralized load balancing algorithms in clustered storage environment

Abstract

Load balance is critical for large-scale storage systems to produce high I/O performance. Decentralized solutions are especially preferred for no single point of bottleneck. We implement four typical hypercube-based decentralized load balancing algorithms in a prototype storage system, and conduct extensive experiments with the system running on a testbed comprising 32 nodes. We compare the efficiency and scalability of the four algorithms through the experiments. The comparison results lead to the following new observations contrary to the conclusions obtained in previous simulation studies. Firstly, algorithms with no redundant load migration do not actually achieve savings of migration costs. Secondly, algorithms tolerating a certain degree of redundancy in load migration may achieve improvements in scalability. The two observations provide new insights into the design of load balancing algorithms in distributed storage systems. © 2013 Springer-Verlag.