【摘要】：在信息技術(shù)飛速發(fā)展的今天,數(shù)字產(chǎn)品也日益普及,數(shù)據(jù)的存儲(chǔ)與管理已成為人們關(guān)注的焦點(diǎn)。NAND Flash由于其價(jià)格低、體積小、存儲(chǔ)量大等實(shí)用性特點(diǎn)成為嵌入式數(shù)據(jù)存儲(chǔ)的主要介質(zhì)。考慮NAND Flash的硬件特性,有必要對(duì)其進(jìn)行數(shù)據(jù)存儲(chǔ)管理。NAND Flash存儲(chǔ)管理的主要方法有兩種：一種是通過閃存轉(zhuǎn)換層將NAND Flash模擬成磁盤設(shè)備,采用通用文件系統(tǒng)進(jìn)行管理；另一種是采用專門為NAND Flash設(shè)計(jì)的文件系統(tǒng)對(duì)其進(jìn)行管理。考慮到以NAND Flash為存儲(chǔ)設(shè)備的嵌入式系統(tǒng)一般都需要與計(jì)算機(jī)進(jìn)行數(shù)據(jù)通信,采用第一種方法對(duì)NAND Flash進(jìn)行存儲(chǔ)管理設(shè)計(jì)可以保證與通用桌面系統(tǒng)的兼容性。 本文的設(shè)計(jì)針對(duì)廣泛應(yīng)用的NAND Flash存儲(chǔ)器,設(shè)計(jì)并實(shí)現(xiàn)閃存轉(zhuǎn)換層將NAND Flash模擬成塊設(shè)備,采用FAT文件系統(tǒng)對(duì)存儲(chǔ)數(shù)據(jù)進(jìn)行管理。論文分析了FAT文件系統(tǒng)的規(guī)范和實(shí)現(xiàn)形式,深入理解了NAND Flash存儲(chǔ)管理技術(shù),包括地址映射、壞塊管理、磨損均衡、掉電保護(hù),并重點(diǎn)對(duì)NAND Flash存儲(chǔ)管理的關(guān)鍵技術(shù)的實(shí)現(xiàn)進(jìn)行了分層介紹。 論文的具體工作包括以下幾個(gè)方面：(1)設(shè)計(jì)了適用于大容量NAND Flash的地址映射機(jī)制。采用了兩種方式對(duì)地址映射表進(jìn)行存儲(chǔ),即使在突然掉電的情況下,也能對(duì)地址映射表快速恢復(fù),提高了存儲(chǔ)的可靠性。(2)對(duì)NAND Flash在出廠時(shí)和使用過程中產(chǎn)生的壞塊進(jìn)行分別處理。出廠時(shí)的壞塊在NAND Flash初始化時(shí)進(jìn)行標(biāo)記并屏蔽。使用過程中的壞塊,采用動(dòng)態(tài)壞塊管理方式,對(duì)NAND Flash使用過程中遇到的擦寫失敗的塊進(jìn)行替換。(3)針對(duì)NAND Flash擦除次數(shù)有限的物理特性,將NAND Flash中每個(gè)物理塊的擦除情況都記錄在一個(gè)磨損均衡表中,根據(jù)這些信息實(shí)現(xiàn)塊的均勻擦寫。由于嵌入式設(shè)備的內(nèi)存有限,故本文設(shè)計(jì)了低內(nèi)存消耗的磨損均衡機(jī)策略,盡可能保證各個(gè)物理塊的擦寫次數(shù)相近,延長了NAND Flash的使用壽命。(4)采用USB通信協(xié)議實(shí)現(xiàn)了NAND Flash設(shè)備和主機(jī)的通信,并在主機(jī)上對(duì)系統(tǒng)的功能和性能進(jìn)行測(cè)試。
[Abstract]:With the rapid development of information technology, digital products are becoming more and more popular. The storage and management of data has become the focus of attention. NAND Flash is small because of its low price. Large storage capacity and other practical characteristics of embedded data storage become the main medium. Considering the hardware characteristics of NAND Flash, there are two main methods of data storage management. NAND Flash storage management. One is to simulate NAND Flash into disk device by flash transfer layer and manage it by general file system. The other is to use a file system specifically designed for NAND Flash to manage it. Considering that the embedded system with NAND Flash as the storage device generally needs to communicate with the computer, the design of storage management for NAND Flash by the first method can guarantee the compatibility with the general desktop system. The design of this paper aims at the widely used NAND Flash memory, designs and realizes the flash memory conversion layer simulates the NAND Flash into the block device, uses the FAT file system to manage the storage data. In this paper, the specification and implementation of FAT file system are analyzed, and the storage management technology of NAND Flash is deeply understood, including address mapping, bad block management, wear balance, power failure protection, etc. The key technologies of NAND Flash storage management are introduced in detail. The main contents of this paper are as follows: (1) address mapping mechanism for large capacity NAND Flash is designed. The address mapping table is stored in two ways. Even in the case of sudden power failure, the address mapping table can be restored quickly. The reliability of storage is improved. (2) the bad blocks produced by NAND Flash are treated separately. Factory bad blocks are marked and shielded during NAND Flash initialization. In the process of using the bad block, the dynamic bad block management method is used to replace the block that the erasure failure encountered during the use of NAND Flash. (3) aiming at the physical characteristic of the limited number of NAND Flash erasures, The erasure of each physical block in NAND Flash is recorded in a wear equalization table, according to which the block is uniformly erased. Because of the limited memory of embedded devices, this paper designs a wear equalizer strategy of low memory consumption, which ensures that the number of erasures of each physical block is close as much as possible. The service life of NAND Flash is prolonged. (4) USB communication protocol is used to realize the communication between NAND Flash device and host, and the function and performance of the system are tested on the host computer.
【學(xué)位授予單位】：廣東工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TP333

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本文編號(hào)：2180193