The Optimization of the Hierarchical Storage System Based on the Hybrid SSD Technology

This paper introduces the hierarchical storage system (HSM) which is adopted in most computers in consideration of achieving a good balance between cost and performance. As the cost of Flash memory rapidly decreases, Flash-based Solid-State Disk (SSD) is used as a non-volatile cache between the DRAM and Hard Disk Drive (HDD) in the HSM. Although typical SSD can deliver higher performances than HDD can, SSD is currently not adopted in most systems due to its limited life and performance. This study introduces a Hybrid SSD approach that combines DRAM, Phase Changed Memory (PCM) and Flash. Even the Flash architectures has its own drawbacks, the Hybrid SSD could support full capabilities benefit by PCM and DRAM. The performance gap between HDD and DRAM will be narrowed by Hybrid SSD more than the pure Flash SSD while delivering a longer endurance life. So, the HSM is well optimized by lead in a Hybrid SSD between the DRAM and HDD.