1+1 Protection of Overlay Distributed Computing Systems: Modeling and Optimization

The development of the Internet and growing amount of data produced in various systems have triggered the need to construct distributed computing systems required to process the data. Since in some cases, results of computations are of great importance, (e.g., analysis of medical data, weather forecast, etc.), survivability of computing systems, i.e., capability to provide continuous service after failures of network elements, becomes a significant issue. Most of previous works in the field of survivable computing systems consider a case when a special dedicated optical network is used to connect computing sites. The main novelty of this work is that we focus on overlay-based distributed computing systems, i.e., in which the computing system works as an overlay on top of an underlying network, e.g., Internet. In particular, we present a novel protection scheme for such systems. The main idea of the proposed protection approach is based on 1+1 protection method developed in the context of connection-oriented networks. A new ILP model for joint optimization of task allocation and link capacity assignment in survivable overlay distributed computing systems is introduced. The objective is to minimize the operational (OPEX) cost of the system including processing costs and network capacity costs. Moreover, two heuristic algorithms are proposed and evaluated. The results show that provisioning protection to all tasks increases the OPEX cost by 110% and 106% for 30-node and 200-node systems, respectively, compared to the case when tasks are not protected.