Collaborative Storage for Tiered Cloud and Edge: A Perspective of Optimizing Cost and Latency

Edge storage is emerging as a novel storage paradigm, which offers the advantage of low latency and low cost, but has the disadvantage of limiting the scope of services to a certain area. In contrast, cloud storage offers anywhere services but has disadvantages in terms of latency and cost. In this paper, a collaborative storage scheme is proposed to leverage their complementary advantages. Considering the impact of collaboration on the cloud and the edge, we propose collaborative optimization models for cost and latency. To address the challenge of requiring future information when performing optimization for cost and latency, we first transform the long-term optimization into individual optimizations in each time slot using the Lyapunov optimization technique, based on which our algorithm decides whether a replica should be created at the edge and which cloud tier a replica should be migrated to. Then, we prove that the proposed algorithm can obtain near-optimal costs and guaranteed latencies. Finally, we conduct extensive simulations driven by real-world traces, and show that our algorithm can achieve a trade-off between cost and latency and outperform other benchmark algorithms.