Flash Storage Management Algorithm for Large-Scale Hybrid Storage Systems

As the computing platforms have evolved over the years, the associated storage requirements have also followed a rapid change in terms of performance, cost, availability and scalability. In addition, computing elements, mainly the CPU, are continuing to scale and develop at a higher pace compared to storage systems. Flash-based solid-state drives (SSDs) have led to significant innovations in storage systems architecture. However, due to their special design and architecture characteristics, they are not considered as cost-effective and immediate replacement of traditional hard-disk drives for large-scale storage systems. Thus, how we can best utilize this technology to build an efficient hybrid storage system remains a research challenge. We propose a real-time dynamic programming algorithm, called Flash Storage Management (FSM) algorithm, to address this challenge. The FSM algorithm can run in two modes: online and offline modes. We implement the proposed FSM algorithm in an event-driven simulator. To compare the FSM algorithm, we implement a simulator for the closest algorithms in the literature, which is Hystor. Our evaluation results indicate that the proposed algorithm outperforms Hystor, especially for read-intensive workloads. For example, the online FSM algorithm achieves a hit ratio of 75% when using SSD size of 30% of the workload, which outperforms Hystor by more than 20%.