Design And Implementation Of NAND Flash Storage Management

In today’s rapid development of information technology and the increasing popularity of digital products, people tend to focus on the storage and management of data.NAND flash is increasingly becoming the main medium of the embedded data storage with the practical features of low price, small size and huge storage capacity. Consider the hardware characteristics of NAND Flash, it is necessary to manage the data storage.There are two kind of methodology applied to management of NAND Flash storage. The first one is using Flash Translation Layer to simulate it as a traditional disk block device and apply a traditional file system to manage it. The other is to manage it using specialized file systems. Considering the NAND Flash storage devices with embedded systems are generally required for data communication with the computer, using the first method of NAND Flash storage management designed to ensure compatibility with the common desktop system.This article is designed for NAND Flash memory which is a wide range of applications, designed and implemented the Flash Translation Layer to simulate NAND Flash memory as block device, using the FAT file system to manage the store data. This paper analyzes the specification and implementing form of the FAT file system, in-depth understanding of the NAND Flash memory management techniques, including address mapping, bad block management and wear leveling, power protection, and focus on layered introduce the implement of this key technologies of NAND Flash storage management.The specific work of papers include the following aspect:(1) Address mapping mechanism is designed for large-capacity NAND Flash’s. There are two ways to store the address mapping table, in case of sudden power loss, it can be quickly rebuild the address mapping table,which improving the storage reliability.(2) NAND Flash bad blocks are dealt with separately in produced at the factory and use. The bad blocks which produced at the factory are marking and shield when NAND Flash initialization.To the bad blocks which produced in use,using dynamic bad block management replacement of the block for the erase failure.(3) Considering the physical characteristics of NAND Flash, Using a wear-leveling table to recorded the numbers of the block erase,based on this information to achieve the uniform of block erase.Due to the limited memory of embedded devices, so this article is designed to wear leveling in low memory consump-tion policy,as far as possible to ensure the physical endurance of each block are similar, extended the using life of NAND Flash.(4) Using USB communication protocol achieve the communication between NAND Flash device and the host, and testing the function and performance of the system in the host.