I/O Optimizations for Hybrid File System Integrated with NAND-Flash SSD

摘要

As the technology of NAND flash memory rapidly grows, SSD is becoming an excellent alternative for storage solutions, due to its high random I/O throughput and low power consumption. These SSD potentials have drawn great attention from IT enterprises that seek for better I/O performance. However, high SSD cost per capacity makes it less desirable to construct a large-scale storage subsystem solely composed of SSDs. An alternative is to build a hybrid storage subsystem where both HDD and SSD are incorporated in an economic manner, while employing the strengths of both devices. This paper presents a hybrid file system, called NF-hybrid (New Form of hybrid), that attempts to utilize the advantages of both HDD and SSD, to provide a single, virtual address space. Especially, NF-hybrid proposes I/O optimizations that contribute to generate better I/O performance, while addressing the restricted SSD storage capacity. Several performance evaluations were conducted to verify the effectiveness and suitability of NF-hybrid.