Flash存储管理在嵌入式系统中的实现

针对大容量存储管理问题,论述管理NAND Flash系统中直接寻址的算法实现,提出建立节点树、底层节点动态位宽等概念,实现对不同类型闪存进行灵活可变的直接寻址。通过建立页数组增大文件系统的直接寻址范围,根据区块数据不同的更新频率分别设计动态损耗均衡算法和静态损耗均衡算法,用于实现需求块回收和损耗均衡。     

面向异构DHT存储的数据与位置解耦算法

分布式哈希表(distributed hash table, DHT)由于其高效的数据寻址方式而被广泛应用于分布式存储.传统DHT必须将数据存放在指定节点中才能实现高效的数据分布式寻址,极大地限制了DHT技术的应用范围.例如,在异构存储网络中,节点的存储空间、带宽、稳定性等均有较大差异,结合数据特征和节点性能差异选择合适的数据存放节点可以很大程度上提高数据的访问效率,而传统DHT数据和存储位置紧耦合的特征导致其难以应用于异构的存储网络中.针对此问题,提出了vRoute算法以实现DHT中数据标识与其存储位置的解耦.通过构建基于Bloom Filter的分布式数据索引, vRoute算法可以在不降低数据寻址效率的基础上允许数据存储在网络中的任意节点.通过扩展Kademlia算法实现了vRoute,并从理论上证明了vRoute算法的有有效性.最后,模拟实验表明vRoute以较低的存储、网络开销实现了和传统的DHT算法接近的数据寻址效率.     

分布式多计算机系统中的存储扩充问题及其解决办法

在大规模分布式多计算机系统中,内外存之间容量的差距正在减小,这极大地影响了操作系统中存储管理的设计和实现。操作系统设计得必须解决在外存存量不足的情况下如何实施存储扩充。提出了指令对文件直接寻址的概念及其实现方法,并分析了指令对文件直接寻址如何解决了这个问题。     

物联网资源寻址模型

通过分析物联网资源寻址特性,对互联网资源寻址的层次迭代模型进行扩展.提出物联网资源寻址的通用层次模型,为解决由多种物品编码标准共存而引起的物联网资源寻址的特有问题提供理论模型依据.根据此模型,建立物联网资源寻址的应用结构模型,并通过对其功能性的实现,验证了通用层次模型的有效性及可行性.     

内容寻址网络性能分析及优化

介绍了内容寻址网络的基本结构和工作原理,分析了内容寻址网络的3种基本操作：节点加入,节点失效以及寻路。该文从最大面积寻路、对角线寻路、层次化结构等3个方面提出了改进CAN寻路性能的措施,并通过仿真证实了这些措施对性能的改善。     

物联网资源寻址模型

通过分析物联网资源寻址特性,对互联网资源寻址的层次迭代模型进行扩展.提出物联网资源寻址的通用层次模型,为解决由多种物品编码标准共存而引起的物联网资源寻址的特有问题提供理论模型依据.根据此模型,建立物联网资源寻址的应用结构模型,并通过对其功能性的实现,验证了通用层次模型的有效性及可行性.     

无线传感器网络与IPv6网络的互联通信

设计无线传感器网络（WSN）与IPv6网络无缝互联的通信模型,给出一种传感器地址自动配置算法,实现传感器节点的自动路由寻址。提出一种适用于WSN的IPv6协议裁剪方案,以节省传感器节点的功耗。在实验平台以及仿真环境中实现了该模型,并对其性能进行分析,实验结果证明了该模型的有效性和正确性。     

单片机存贮器多页面扩展技术

单片机程序存贮器和数据存贮器的直接寻址空间均为６４ｋＢ，对复杂系统的开发往往是不够的。以６４ｋＢ为一个页面，提出了一种存贮器多页面扩展方法，利用单片机多余取指脉冲，实现了程序跨页面连续运行和寻址     

基于内容寻址网络的结构化P2P系统的研究

本文介绍了内容寻址网络(ContentAddressableNetwork:CAN)的概念。CAN利用分布式哈希表(DistributedHashTable:DHT)实现了文件信息和存放位置的有效映射,具有完全自组织和分布式的结构(不需要任何形式的中心控制、协调或配置),并且有良好的可扩展性(节点只维护少量的控制状态,与系统中的节点数无关)和容错性(节点失效后仍可通过别的路由路径寻路)。     

实现无线传感器网络与IPv6网络互联的一种方案

提出并设计了无线传感器网络与IPv6网络无缝互联的通信模型。此模型提出了一种传感器地址自动配置方案,并在此方案之上实现了传感器节点的自动寻址路由。此外,给出了一种适用于无线传感器网络（WSN）的IPv6协议裁剪方案,以节省传感器节点的功耗。在实验平台及仿真环境中,实现了模型并且分析了模型的性能,实验结果证明了此模型的有效性和正确性。     

NAND Flash在嵌入式系统中的应用

首先比较了嵌入式系统中两种常用的Flash器件,指出Nand-Flash的优势.然后以SUMSANG公司的K9F1G08为例介绍了Nand-Flash的组织结构与硬件接口.最后简要论述了Nand-Flash驱动程序的编写要点.     

A hybrid flash translation layer design for SLC-MLC flash memory based multibank solid state disk

This paper presents the design of a NAND flash based solid state disk (SSD), which can support various storage access patterns commonly observed in a PC environment. It is based on a hybrid model of high-performance SLC (single-level cell) NAND and low cost MLC (multi-level cell) NAND flash memories. Typically, SLC NAND has a higher transfer rate and greater cell endurance than MLC NAND flash memory. MLC NAND, on the other hand, benefits from lower price and higher capacity. In order to achieve higher performance than traditional SSDs, an interleaving technique that places NAND flash chips in parallel is essential. However, using the traditional FTL (flash translation layer) on an SSD with only MLC NAND chips is inefficient because the size of a logical block becomes large as the mapping address unit grows. In this paper, we proposed a HFTL (hybrid flash translation layer) which makes use of chained-blocks, combining SLC NAND and MLC NAND flash memories in parallel. Experimental results show that for most of the traces studied, the HFTL in an SSD configuration composed of 80% MLC NAND and 20% SLC NAND memories can improve performance compared to other solid state disk configurations, composed of either SLC NAND or MLC NAND flash memory alone.     

Next high performance and low power flash memory package structure

In general, NAND flash memory has advantages in low power consumption, storage capacity, and fast erase/write performance in contrast to NOR flash. But, main drawback of the NAND flash memory is the slow access time for random read operations. Therefore, we proposed the new NAND flash memory package for overcoming this major drawback. We present a high performance and low power NAND flash memory system with a dual cache memory. The proposed NAND flash package consists of two parts, i.e., an NAND flash memory module, and a dual cache module. The new NAND flash memory system can achieve dramatically higher performance and lower power consumption compared with any conventionM NAND-type flash memory module. Our results show that the proposed system can reduce about 78% of write operations into the flash memory cell and about 70% of read operations from the flash memory cell by using only additional 3KB cache space. This value represents high potential to achieve low power consumption and high performance gain.     

非易失存储器NAND Flash及其在嵌入式系统中的应用

文中介绍了NAND Flash的芯片内部组织结构、主要的外部引脚及其功能、NAND Flash的类型、NAND Flash所支持的文件系统、与微处理器的连接和NAND Flash的固有特性,并对比了NAND和NOR Flash的异同。最后简述了闪存固件程序架构和如何在Linux操作系统中加入对NAND Flash的支持。     

U-Boot在s3c2410上的移植及功能扩展

考虑到Bootloader在嵌入式系统开发及产品升级方面的重要性及近年来NAND Flash闪存在嵌入式系统应用中的广泛性,提出了U-Boot从NAND Flash闪存设备启动的方法.详细地介绍了U-Boot源码结构及其启动流程,并分析了NAND Flash闪存工作原理及操作方法,实现了U-Boot从NAND Flash闪存启动以及U-Boot以命令行形式操作NAND Flash的功能.最后,实验结果表明了U-Boot在s3c2410处理器上成功的移植.     

Design and implementation of MLC NAND flash-based DBMS for mobile devices

Recently, Multi-Level Cell (MLC) NAND flash memory is becoming widely used as storage media for mobile devices such as mobile phones, MP3 players, PDAs and digital cameras. MLC NAND flash memory, however, has some restrictions that hard disk or Single-Level Cell (SLC) NAND flash memory do not have. Since most traditional database techniques assume hard disk, they may not provide the best attainable performance on MLC NAND flash memory. In this paper, we design and implement an MLC NAND flash-based DBMS for mobile devices, called AceDB Flashlight, which fully exploits the unique characteristics of MLC NAND flash memory. Our performance evaluations on an MLC NAND flash-based device show that the proposed DBMS significantly outperforms the existing ones.     

嵌入式Linux下NAND存储系统的设计与实现

讨论嵌入式Linux下与NAND闪仔存储设备相关的Linux MTD子系统、NAND驱动，并就与NAND闪存相关的文件系统、内核以及NAND闪存存储没计所关注的问题如坏块处理、从NAND启动、当前2．4和2．6内核中NAND通用驱动所存在的缺陷进行讨论并给出解决方案。以Omap161x H2开发板为例，给出了NAND闪存存储实现实例并指出设计中需要关注的问题。     

NAND闪存存储文件系统

NAND闪存已经成为便携式设备的主要存储介质。由于闪存自身的物理特性,需要在现有文件系统层与闪存的存储物理层之间引入闪存转换层。但是,现有文件系统主要针对磁盘存储系统设计的,没有考虑NAND闪存物理特性。这种方法效率低、影响便携式设备的性能。本文概述了NAND闪存的存储文件系统,分析比较了其中三种主要文件系统,为基于NAND闪存存储介质的便携式系统设计提供了参考意见。     

Flash存储管理的研究与设计

针对目前存储管理对大容量NAND Flash考虑的不足,在对大容量NAND Flash物理特性深入研究的基础上,实现了连续写与非连续写技术,提高了存储管理的效率.首先研究并实现了特有的状态信息描述方法,完全符合大容量MLC类型NAND Flash的物理特性,研究并实现了区域映射技术,适用于任何容量的闪存,并实现了连续写与非连续写技术,提高了写大文件的效率.实验结果表明,该方法在文件传输方面最大限度地挖掘了MLC类型NAND Flash的性能.     

A high performance NAND array file system based on multiple NAND flash memories

The existing NAND flash memory file systems have not taken into account multiple NAND flash memories for large-capacity storage. In addition, since large-capacity NAND flash memory is much more expensive than the same capacity hard disk drive, it is cost wise infeasible to build large-capacity flash drives. To resolve these problems, this paper suggests a new file system called NAFS for large-capacity storage with multiple small-capacity and low-cost NAND flash memories. It adopts a new cache policy, mount scheme, and garbage collection scheme in order to improve read and write performance, to reduce the mount time, and to improve the wear-leveling effectiveness. Our performance results show that NAFS is more suitable for large-capacity storage than conventional NAND file systems such as YAFFS2 and JFFS2 and a disk-based file system for Linux such as HDD-RAID5-EXT3 in terms of the read and write transfer rate using a double cache policy and the mount time using metadata stored on a separate partition. We also demonstrate that the wear-leveling effectiveness of NAFS can be improved by our adaptive garbage collection scheme.