The Design And Implementation Of Flash Translation Layer Based On Semantic Of Data Type

NAND Flash memory has a good read and write speed,as well as an outstanding performance in terms of low power consumption,high storage density,non-volatile,shock resistance and so on,so it is widely used in mobile products,servers and other fields.With the progress of the manufacturing technique,storage density of NAND Flash chip is getting higher and higher,capacity of the Solid State Drive(SSD)formed from NAND Flash chips is growing.The internal ram of the SSD is usually used to store the whole or the part of mapping table,but with the increase of the SSD capacity,the ram space the Flash Translation Layer(FTL)required to maintain mapping increases.It has led to the challenge of traditional management method.The existing FTL of the SSD can not parse the semantics of the host-side storage access.The use of flash pages and flash blocks for the granularity of the solid-state disk storage space management,limited memory capacity can not solve the problems of large-capacity flash page management overhead.By modifying the existing file system and IO path,the relevant semantic information can be passed to the SSD.Through the host-side storage request to analyze the characteristics of the request data and classification processing.The file system metadata using page-level mapping with better performance,and the user data using variable granularity to manage flash memory storage space management,by thus reducing the amount of memory with traditional page mapping table required and improving the system performance.Moreover,the design scheme is implemented on an open source SSD simulator to evaluate its efficiency.The results show that the scheme can effectively reduce the memory space required for maintenance mapping of large capacity SSD,improve the system performance and prolong the service life of SSD.