The Research And Implementation Of Flash File System & Flash Storage Management Issues

Nowadays, flash memory is prevailing in many mobile devices such as MP3 players, flash memory cards, cell phones and PDAs due to its non-volatility, solid-state reliability, small and lightweight package, low-power consumption, etc. Common file systems can not be directly applied to flash memory, so the Flash Translation Layer (FTL) should be designed to allow file system to read and write to flash memory device in the same way as disk drive.Aiming at the widely used NAND flash memory, a FTL is designed and implemented, so the FAT file system is created on NAND flash. Specially, the NAND flash memory storage management issues are deeply researched, including address mapping, wear-leveling algorithm, garbage collection policy, power-off recovery, bad block management, and so on. As well as much more emphases are taken on the problem of identifying user and data security, encrypted-storage mechanism is designed and implemented. Additionally, this paper proposes layered software architecture of flash memory storage management and intends to research and develop a software module for NAND Flash memory, which is obtained application in the actual product.The following achievements are made in this dissertation: (1) The architecture of flash file system and its implementation form are deeply researched. (2) A NFTL mapping scheme is designed and deeply analyzed for large capacity NAND Flash. (3) Wear-leveling algorithm and garbage collection policy are researched for better system performance and longer flash memory lifespan. (4) Power-off recovery mechanism and bad block management are designed for system higher reliability. (5) Research and implementation of flash memory storage encryption, including user identification and data encryption.