The Design And Implementation Of A Tired File System Based On SSD And HDD

The rapid growth of storage and data requires the information system to supply more storage capacity and higher speed. Tiered storage is one important technology which can handle the capacity and speed problem. By designing storage system based on the data value and access pattern, tiered storage brings better performance. The widely use of the Solid State Drives (SSDs) introduces many challenges to the design of modern tiered storage system. SSDs bring higher I/O performance than traditional Hard Disk Drives (HDDs). Meanwhile, some new problems of the SSDs are also emerged, e.g., the wear-leveling problem, as well as the high price of SSDs.In order to combine SSDs and HDDs together effectively and to construct a better tiered storage system, this paper studied the development of storage system and kernel file system and SSDs, then designed a SSD-based tiered file system called FMCFS. By managing the disk drive space and solid state drive space effectively, and recording the historic access information, and identifying the hottest data blocks, FMCFS can migrate data blocks between SSDs and HDDs automatically at the file block level. The paper also studied the critical issues of designing tiered file system, such as the identification of hot data and high-valued data, the management of massive meta-data, and the optimization of access of the SSDs. It shows that by IO redirecting, the data blocks of one file can be placed on different devices.The analysis of FMCFS (Flash Magnetic Combined File System) demonstrates that, by replacing the most accessed file data blocks and high-valued data blocks on the solid state drives, the high I/O throughput of solid state drives and the massive capacity of hard disk drives together bring a cost-effective storage system, and accelerate the overall performance of the system. The impact of the wearing problem of solid state drives is also reduced effectively.