Research On The NAND Flash File System Of The Embedded System

Because of their own characteristics and requirements of embedded systems, embedded storage devices must be small and low power consumption and quakeproof, obviously devices such as disk storage media do not have these characteristics, so they are not suitable for storing data in embedded systems. Flash memory has low cost, storage capacity, small size, low power consumption characteristics. Compared with the disk, it is more suitable for storing data in embedded systems and has become an embedded mobile storage platform of choice for storage media.With the continuous development of embedded technology and the increasingly wide range of applications, embedded systems for data storage and data management requirements have become more sophisticated. In recent years, the embedded Flash memory file system continues to emerge, which is mainly divided into three categories: block-based file system for embedded devices, such as FAT32 and Ext2, general embedded Flash file system, such as JFFS series, dedicated embedded Flash file system, so far only YAFFS series. The first embedded file system is actually a disk-based block device file system to the Flash memory of the transplant; second transplant embedded file system discarded the idea, is designed specifically for Flash memory common file system, both in NOR Flash on the run, they can also be run on NAND Flash; the last category the file system is designed specifically for NAND Flash File System. Three types of file system embody three development stages of embedded file systems. Although compared with the previous phase each stage has made tremendous progresses, the NAND Flash-based embedded file system still has many disadvantages: mounting time too long, but specifically for NAND Flash file system on the loss does not fully take wear-leveling into account.For the shortage of NAND flash file system, this paper presents an improved method. First in the existing NAND Flash file system, a Flash erase block while preserving the file attribute information and data, when mounted by block scanning, mounting time increases with the increasing storage capacity Great. This has changed the management of this file information, the file attribute information and data are stored in a different erase block, mounting only the scan attribute blocks, thereby reducing the mounting time of the file system. Second the existing NAND Flash file system on the implementation of static data loss is not well wear-leveling. In this paper, according to hot and cold data ideas, erase block will be classified management, frequent changes of the properties of nodes and only rarely modified by the static read large data loss while achieving a balance.According to the above methods, based on existing YAFFS file system, this paper implements a new file system MFFS (Modified Flash File System). The results of testing and theoretical analysis show that, MFFS improved greatly against YAFFS in terms of mount-time and wear-leveling.Theoretical analysis can not consider every aspect. It needs some experiments to demonstrate whether the MFFS File System can reach the anticipated effects. As for this, there are some other works to be done.The implementation of MFFS file system has certain significance for reducing the mounting time and extending the life of flash.