Towards Network-Aware Divisible Load Theory for Optical Grids

Most grid applications require the processing of large amounts of data stored at different locations across the network which makes optical grid infrastructures optimal for such applications. The increase in intensity of data- and communications of these applications calls for new mechanisms and theories on how to optimally allocate optical grid resources. Typical Divisible Load Theory (DLT) makes optimal allocation of computational resources. In this paper, we introduce Network Aware Divisible Load Algorithm (NADLA) that extends DLT to optimally allocate both the computational and networking resources of an optical grid. We assume a data- and communications-intensive application where data is stored at different sites across the optical grid and can be divided into independent subsets to be processed in parallel at different sites. The algorithm defines an optimal data transfer schedule that defines when to transfer what data subsets to which sites across the optical grid in order to minimize the overall application completion time. It consists of two phases. In the first phase, NADLA provide load distribution that minimizes application completion time taking into account network connectivity and computational and networking resources availability. Site connectivity is estimated by considering the bandwidth and the expected free time of all the links connecting this site to other sites. In the second phase, a simple greedy algorithm is used to allocate computational and networking resources. Extensive Simulations are conducted to examine the performance of the proposed algorithm for different application types and sizes, and different optical grid topologies. Simulation results show the advantages of the proposed algorithm over the traditional DLT approach for the category of applications considered.