嵌入式NAND Flash存储系统的设计与实现
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摘要
随着信息技术的发展和数字产品的普及,嵌入式系统已经成为当今计算机技术研究与应用的一大热点。NAND Flash存储器作为一类非易失性存储器,具有功耗低、读写快、容量大、成本低、抗震性好等优点而被广泛应用于各种嵌入式系统。NAND Flash存储器的管理主要有两种方法：一种是将NAND闪存存储器通过闪存翻译层(FTL)模拟成可随意读写的块设备,使用传统的文件系统进行管理；另一种就是针对NAND闪存的存储特性,使用专门设计的文件系统进行管理。本课题设计就是利用FTL层的方法为移动上网设备设计并实现了基于嵌入式Linux的NAND Flash存储系统,包括块设备层,FTL层,LLD层的设计与实现。
本论文首先主要介绍了嵌入式系统当前的背景及发展现状,以及嵌入式NAND Flash存储系统开发课题的项目背景、该课题的选题意义和主要工作。然后,主要介绍主流的Flash技术和Flash存储设备,对最主流的NOR Flash和NAND Flash进行了对比,并着重介绍了NAND Flash的使用,最后介绍了我们设计中采用的NAND Flash芯片。接下来,重点分层具体详细的介绍了这次课题的NAND Flash存储系统的设计与实现方法,并重点介绍了对于块接口层的改写、缓存算法的改进、对地址映射表存放策略的优化以及一种我们使用的负载均衡算法。最后,对课题的研究情况进行了总结,并对系统的后续开发,从硬件改进和系统整合等方面进行了展望。
With the development of information technology and wide usage of digital products, nowadays embedded system becomes a hotspot in computer technology area. NAND Flash memory is a non-volatile solid state memory and is widely used in many embedded systems because of its low power consumption, fast I/O, large capacity, low cost, shock resistance property and etc. There are two kind of methodology applied to management of Flash storage. The first one is using FTL (Flash Translation Layer) to simulate it as a traditional R/W block device and apply a traditional block file system to manage it. The other is to manage it using specialized file systems. In this paper, an embedded Linux NAND Flash storage system using FTL for mobile internet device is designed and implemented. It includes block layer, FTL layer and LLD layer.
This paper first introduces the background and current status of embedded system. The background and value of NAND Flash storage system development project are also be referred. Then, this paper focuses on the Flash technology and Flash memory devices. NOR Flash and NAND Flash are compared in this paper. The usage of NAND Flash is introduced with an emphasis. The last part of this chapter introduces the NAND Flash chips we used. Next, this paper demonstrated about how to design and implement NAND Flash storage system hierarchically,, and emphasized on redesign of block interface layer, optimization of cache replacement algorithm, method of address mapping table storing and wear leveling algorithm we used. At last, the paper summarized about the development of the system and gave an expectation of future developing of the system, including hardware improvement and embedded USB host system's integration to video phone system task.
本论文首先主要介绍了嵌入式系统当前的背景及发展现状,以及嵌入式NAND Flash存储系统开发课题的项目背景、该课题的选题意义和主要工作。然后,主要介绍主流的Flash技术和Flash存储设备,对最主流的NOR Flash和NAND Flash进行了对比,并着重介绍了NAND Flash的使用,最后介绍了我们设计中采用的NAND Flash芯片。接下来,重点分层具体详细的介绍了这次课题的NAND Flash存储系统的设计与实现方法,并重点介绍了对于块接口层的改写、缓存算法的改进、对地址映射表存放策略的优化以及一种我们使用的负载均衡算法。最后,对课题的研究情况进行了总结,并对系统的后续开发,从硬件改进和系统整合等方面进行了展望。
With the development of information technology and wide usage of digital products, nowadays embedded system becomes a hotspot in computer technology area. NAND Flash memory is a non-volatile solid state memory and is widely used in many embedded systems because of its low power consumption, fast I/O, large capacity, low cost, shock resistance property and etc. There are two kind of methodology applied to management of Flash storage. The first one is using FTL (Flash Translation Layer) to simulate it as a traditional R/W block device and apply a traditional block file system to manage it. The other is to manage it using specialized file systems. In this paper, an embedded Linux NAND Flash storage system using FTL for mobile internet device is designed and implemented. It includes block layer, FTL layer and LLD layer.
This paper first introduces the background and current status of embedded system. The background and value of NAND Flash storage system development project are also be referred. Then, this paper focuses on the Flash technology and Flash memory devices. NOR Flash and NAND Flash are compared in this paper. The usage of NAND Flash is introduced with an emphasis. The last part of this chapter introduces the NAND Flash chips we used. Next, this paper demonstrated about how to design and implement NAND Flash storage system hierarchically,, and emphasized on redesign of block interface layer, optimization of cache replacement algorithm, method of address mapping table storing and wear leveling algorithm we used. At last, the paper summarized about the development of the system and gave an expectation of future developing of the system, including hardware improvement and embedded USB host system's integration to video phone system task.
引文
[1]谢苏云 详解嵌入式系统及应用前景 中国电子商情(基础电子)05期2007年
[2]李佑军 嵌入式系统综述 现代电子技术 06期 2003年
[3]冯继超 面向二十一世纪的嵌入式系统及发展方向 工业控制计算机05期2001年
[4]王祥生 嵌入式Linux下大容量Nand闪存文件系统研究 学位论文 浙江浙江大学2007年
[5]G. Lawton Improved Flash Memory Grows in Popularity Computer 39,2006
[6]李强,杜威,暮春棣 基于大容量闪存的嵌入式文件系统计算机工程 31期2005年
[7]MMCA Technique Committee. The Multimedia Card System specification. US:Multimedia card association,2003.
[8]Phil Wilshire eXecute In Place(XIP)overview http://www.ucdot.org 2000年
[9]余一娇Flash Memory技术和应用综述 华中科技大学计算机学院技术报告2004年
[10]刘洲洲,张捷 基于嵌入式系统的NAND Flash坏块处理和FMM实现 计算机技术与应用 26期 2006年
[11]Nobuaki Otsuka, Mark A. Horowitz Circuit Techniques for 1.5V Power Supply Flash Memory IEEE J of Solid-State Circuits 32,1997
[12]M-Systems Corporation TrueFFS:Enabling the Latest NAND Technology for Growing Personal Storage Demands Oct,2006
[13]Mendel Rosenblum, John K. Ousterhout The Design and Implementation of a Log-Structured File System ACM Transactions on Computer Systems (TOCS) Volume 10,February,1992
[14]SELTZER, BOSTIC, K.MCKUSICK, M.K.STAELIN. An implementation of a log structured file system for UNIX USENIX Winter Conference Proceedings 1993
[15]Eran Gal, Sivan Toledo Algorithms and data structures for flash memories. ACM Computing Surveys (CSUR) Volume 37 Issue 2 June,2005
[16]Li-Fu Chou, Pangfeng Liu Efficient Allocation Algorithms for FLASH File Systems Proceeding of the 11th International Conference on Parallel and Distributed Systems Volume 01 2005
[17]STMicroelectronics Co., Ltd Bad Block Management in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1819) 2006
[18]STMicroelectronics Co., Ltd Garbage Collection in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1821) 2004
[19]STMicroelectronics Co., Ltd Wear Leveling in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1822) 2004
[20]Li-Pin Chang On Efficient Wear Leveling for Large Scale Flash Memory Storage Systems SAC'07 March 1115 2007
[21]Hyojun Kim, Seongjun Ahn A Buffer Management Scheme for Improving Random Writes in Flash Storage In Proceedings of the 6th USENIX Symposium on File and Storage Technologies (FAST'08) pages 239-252 2008
[22]Jonathan Corbet, Alessandro Rubini, Greg Kroah-Hartman. Linux Device Drivers.3rd Edition O'Reilly 2005
[23]王标,周新志,罗志平 嵌入式系统中Nand Flash写平衡的研究 微计算机信息2008年
[24]宋宝华LINUX设备驱动开发详解 北京：人民邮电出版社 2008年
[2]李佑军 嵌入式系统综述 现代电子技术 06期 2003年
[3]冯继超 面向二十一世纪的嵌入式系统及发展方向 工业控制计算机05期2001年
[4]王祥生 嵌入式Linux下大容量Nand闪存文件系统研究 学位论文 浙江浙江大学2007年
[5]G. Lawton Improved Flash Memory Grows in Popularity Computer 39,2006
[6]李强,杜威,暮春棣 基于大容量闪存的嵌入式文件系统计算机工程 31期2005年
[7]MMCA Technique Committee. The Multimedia Card System specification. US:Multimedia card association,2003.
[8]Phil Wilshire eXecute In Place(XIP)overview http://www.ucdot.org 2000年
[9]余一娇Flash Memory技术和应用综述 华中科技大学计算机学院技术报告2004年
[10]刘洲洲,张捷 基于嵌入式系统的NAND Flash坏块处理和FMM实现 计算机技术与应用 26期 2006年
[11]Nobuaki Otsuka, Mark A. Horowitz Circuit Techniques for 1.5V Power Supply Flash Memory IEEE J of Solid-State Circuits 32,1997
[12]M-Systems Corporation TrueFFS:Enabling the Latest NAND Technology for Growing Personal Storage Demands Oct,2006
[13]Mendel Rosenblum, John K. Ousterhout The Design and Implementation of a Log-Structured File System ACM Transactions on Computer Systems (TOCS) Volume 10,February,1992
[14]SELTZER, BOSTIC, K.MCKUSICK, M.K.STAELIN. An implementation of a log structured file system for UNIX USENIX Winter Conference Proceedings 1993
[15]Eran Gal, Sivan Toledo Algorithms and data structures for flash memories. ACM Computing Surveys (CSUR) Volume 37 Issue 2 June,2005
[16]Li-Fu Chou, Pangfeng Liu Efficient Allocation Algorithms for FLASH File Systems Proceeding of the 11th International Conference on Parallel and Distributed Systems Volume 01 2005
[17]STMicroelectronics Co., Ltd Bad Block Management in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1819) 2006
[18]STMicroelectronics Co., Ltd Garbage Collection in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1821) 2004
[19]STMicroelectronics Co., Ltd Wear Leveling in Single Level Cell NAND Flash Memories STMicroelectronics Application Note(AN1822) 2004
[20]Li-Pin Chang On Efficient Wear Leveling for Large Scale Flash Memory Storage Systems SAC'07 March 1115 2007
[21]Hyojun Kim, Seongjun Ahn A Buffer Management Scheme for Improving Random Writes in Flash Storage In Proceedings of the 6th USENIX Symposium on File and Storage Technologies (FAST'08) pages 239-252 2008
[22]Jonathan Corbet, Alessandro Rubini, Greg Kroah-Hartman. Linux Device Drivers.3rd Edition O'Reilly 2005
[23]王标,周新志,罗志平 嵌入式系统中Nand Flash写平衡的研究 微计算机信息2008年
[24]宋宝华LINUX设备驱动开发详解 北京：人民邮电出版社 2008年