支持多种NANDFlash的驱动程序研究与实现

NANDFlash具有存储密度高、成本低等优点。非常适合于手持设备的数据存储。该文介绍了在WINCE平台如何实现支持多种类型的NANDFlash的驱动程序,采取分层驱动的体系架构,提高代码复用的程度,便于维护和扩展。添加一种新的类型的NANDFlash．只需用加入很少的代码。     

支持多种NAND Flash的驱动程序研究与实现

NAND Flash具有存储密度高、成本低等优点,非常适合于手持设备的数据存储。该文介绍了在WINCE平台如何实现支持多种类型的NAND Flash的驱动程序,采取分层驱动的体系架构,提高代码复用的程度,便于维护和扩展。添加一种新的类型的NAND Flash,只需用加入很少的代码。     

嵌入式设备NAND Flash存储系统的设计与实现

为了实现一种嵌入式设备存储系统的解决方案,对嵌入式设备广泛采用的大容量存储设备NAND Flash进行了深入的研究.设计了一种嵌入式设备中NAND Flash存储系统的解决方案,介绍了其功能用途和系统结构,分层介绍了系统的具体设计,重点介绍了比较独特的块设备驱动层和FTL层的设计方法以及对驱动初始化的优化.通过实际设计NAND Flash存储系统Linux驱动,说明了该系统设计实际应用时的出色效果.     

Real-time emulation and analysis of multiple NAND flash channels in solid-state storage device

NAND Flash is the most prevalent memory technology used today in data storage systems covering a wide range of applications, from consumer devices to high-end enterprise systems. In this work, we present a modular and versatile FPGA-based platform that achieves accurate emulation of multiple NAND Flash channels. The NAND Flash emulator is based on an expandable and reconfigurable architecture that can be used for developing and testing new NAND Flash controllers and for analysing the behaviour of existing NAND Flash controllers and/or host device drivers. The presented NAND Flash emulator is based on PCIe-based FPGA boards attached to a high-end server, supports standard memory interfaces, responds to all memory commands in proper time and has the capability to emulate memory space in the range of a few TBs. The NAND Flash emulator has been prototyped and tested, and experimental results demonstrate that all timing requirements are satisfied under maximum read/write workloads. The NAND Flash emulator also includes a hardware tracer unit that records information of all commands exchanged at the NAND Flash interfaces along with high resolution timestamps. The recorded information can be used to analyse higher level functions, like wear leveling and garbage collection, and combined with other software tools for analysing cognitive functions. Experimental results demonstrate the advantage of using this emulator for analysing how host device drivers implement wear leveling and garbage collection functions.     

Cloud computing burst system (CCBS): for exa-scale computing system

Computational scientific applications tend to be very data I/O intensive, producing a large amount of data as the execution result. In this research, we propose a new storage system using next-generation non-volatile memory that is suitable for exa-scale computing systems. This storage system is called the Cloud Computing Burst System (CCBS) and is composed of a unified table management module, data scoring module, and CCBS storage. In particular, CCBS operates as a workload enlightened storage system using its own data scoring module. The CCBS storage architecture consists of PCM/NAND Flash arrays and a data migration engine. CCBS storage cannot only provide a scaling out feature, but also improve the overall performance of the storage system. In addition, by using new non-volatile memory array, many benefits, such as low energy consumption, density scaling, and high performance, can be achieved. We demonstrate the effectiveness of our proposed system by simulating the storage system using scientific benchmarking tool. Our data scoring algorithm can provide 7% more hit rate than other methods for CCBS. In addition, our proposed system has improved storage system speed by 1.64 times, compared with only NAND Flash conventional model.     

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.     

基于NAND FLASH的多路并行存储系统中坏块策略的研究

大规模固态闪存系统可以引入多路并行技术来支持高速数据传输,但随着闪存存储容量增加也需要采取有效的坏块处理机制来解决严重的坏块访存问题.面向NAND FLASH多路并行固态存储系统,提出了一种高效坏块管理策略,采取并行存储坏块编码技术来节约坏块表存储空间,减少坏块处理功耗,同时采取坏块表重构处理技术有效解决了系统中的同位置坏块难题.针对四路并行的NAND FLASH存储系统,实验结果表明:该策略节约了25%的坏块表RAM存储空间,提高了约1.5倍的查询效率,降低了约30%的坏块处理功耗,并对并行存储数量具有良好的可扩展性.     

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.     

基于缓存机制的NAND FLASH XIP存储系统

NAND闪存存储器已经成为嵌入式系统中非常重要的组成部分,在各种嵌入式产品中有广泛的应用前景,但NAND闪存存储器目前主要用来数据存储,并不能像NOR FLASH一样以XIP(execute-in-place,芯片内执行)方式执行代码.针对目前3G应用通讯的特点,通过引入缓存机制实现了具有XIP功能的NAND FLASH存储系统,这样大降低了系统的成本,最后根据实验得出结果与其它的存储架构作了比较.     

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.     

固态硬盘性能优化研究与实现

为了实现计算机内部硬盘存储数据的高速要求,通过在FPGA 芯片XC5VFX130T内部构建多通道并行架构的方法,设计了一种基于SATA3.0接口的多通道固态硬盘存储系统。在硬件方面,巧妙地采用了利用NAND Flash 的并行流水机制与有效配置数据缓存相结合的方法来解决系统的存储速度;在软件方面,采用数据补偿策略解决连续地址数据读写时存在的地址偏移问题;并对系统参数以及软硬件数据流程的优化进行了研究与实现。实验测试结果表明,该系统具有存储速度快,并行性和扩展性强等特点。     

基于NAND闪存的固态盘技术研究

基于NAND闪存的固态盘具有非易失、访问速度快、体积小、抗震性好以及功耗低等诸多优点,能较好缓解I/O性能瓶颈问题,已经成为学术界和产业界关注的一个研究热点.对基于NAND闪存固态盘的主要热点问题予以研究,介绍了基于闪存固态盘的技术特性,分析了其内部结构,对其关键实现技术着重进行了研究分析.     

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.     

A user-visible solid-state storage system with software-defined fusion methods for PCM and NAND flash

Existing SSD technology exploits the properties of NAND flash and leverages NAND flash with a controller running FTL algorithms to improve system performance. On one hand, however, in this black-box-modeled structure, data semantic information is hard to be transferred and interpreted by conventional interfaces. Hence, SSD firmware fails to make full use of the performance potential of SSD by utilizing semantic information. Moreover, the host cannot obtain physical characteristics and statistical information about SSD, failing to be used by the file system or I/O scheduling algorithm designed for the disks. On the other hand, in SSD-based storage systems, persistent data are stored in the NAND flash and however manipulated in DRAM, causing the decoupled inefficiency. The data being closer to the processors are much easier to be lost due to the volatile property of DRAM, leading to serious data reliability problems. What’s more, restrictive read/program granularity and out-of-place updates limit the performance while flash suffers from small size operations.In order to address these problems, we propose a user-visible solid-state storage system with software-defined fusion methods for PCM and NAND flash. PCM is used for improving data reliability and reducing the write amplification of NAND flash as PCM shows some outstanding features, such as in-place updates, byte-addressable, non-volatile properties and better endurance. In this system, we manage the storage device as user-visible structure rather than black-box-modeled structure. In detail, we expose the number of channels, erase counts and data distribution of PCM/NAND flash to the host and design FTL algorithm closer to file system to obtain more semantic information of data accessing. PCM can be software-defined as the same level storage or buffer of NAND flash to reduce the WA (Write Amplification) of NAND flash and improve the data reliability. Moreover, some key software components (such as FTL, I/O scheduling and buffer management) are also reconfigurable and operated easily combined with physical characteristics. To achieve these design goals, we implement a Host Fusion Storage Layer (HFSL) and redesign the lengthy I/O path. Applications or filesystem can access PCM/flash directly via provided interfaces by HFSL without passing traditional I/O subsystem. Moreover, we provide the system management software to make the storage system can be easily software-defined by the upper-level system. We implement our software-defined fusion storage system in our actual hardware prototype and extensive experimental results demonstrate the efficiency of the proposed schemes.     

一种多通道并行固态存储系统的设计与实现

鉴于高速数据采集系统对实时数据存储带宽和容量的要求,提出一种基于现场可编程门阵列（FPGA）的高速多通道并行固态存储系统。该系统以现场可编程门阵列器件XCV5LX110T为核心,选用大容量高速闪存芯片作为存储介质,通过采用并行总线拓宽技术和流水线缓冲技术,在FPGA片内搭建高速多通道并行存储硬件架构,从硬件角度提高系统的数据吞吐带宽。设计一种基于超级页的地址映射策略,并使用该策略对闪存转换层算法的请求处理机制进行并行加速优化,从软件角度提高系统的存储并行性。测试结果表明,该系统的最大存储速度达到73MB／s,其性能指标能满足高速实时数据存储的需求,证明多通道存储架构和FTL算法具有良好的并行性和可扩展性。     

一种适用FADEC的NAND Flash文件存储系统

NAND Flash具有容量大、存取数据快的优点.但是,在使用过程中NAND Flash会产生坏块,且坏块是随机分布的.因此,操作NAND Flash需要相当的技巧,不能往坏块里写入数据.同时,NAND Flash更容易发生位翻转,需要使用ECC算法确保信息的正确性.在航空发动机上NAND Flash主要用来记录发动机控制(FADEC)的历史数据.FADEC的历史数据记录要求大容量、实时性和正确性.提出的适用FADEC的NAND Flash的文件存储系统(FFS_N)可以有效地解决NAND Flash使用上的问题,同时满足航空发动机控制历史数据记录要求.     

NAND FLASH编程实现研究分析

以阐明编程支持NAND FLASH的方法为目的。总览了NAND FLASH层次结构;讨论了NAND FLASH的写操作过程,这种写操作的特点也是FLASH有别于其它存储介质的地方,同时也对NAND FLASH的擦除操作做了介绍;在对整体的框架和特点有了了解之后,进一步对编程支持NAND FLASH的过程中会遇到的一些概念和细节给出了具体的说明。对NAND FLASH的编程支持有一定的复杂性,但只要了解了它的工作方式,也并非难事。     

嵌入式Linux中NAND Flash设备驱动研究

NAND Flash作为一种非易失性的存储介质,它具有速度快、体积小、存储密度高和容量大等优点,适用于大量数据的存储,因此在嵌入式领域中的应用也越来越广泛。分析了MTD(内存技术设备)与NAND Flash驱动的关系,总结了典型的NAND Flash驱动程序的总体架构。针对PXA270RP平台,设计和实现了嵌入式Linux下的NAND Flash驱动程序。为编写基于嵌入式Linux系统下的NAND Flash设备驱动程序提供了技术指导。     

嵌入式设备中一种大容量存储系统的软件设计

该文结合工程实践,提出了一个采用NORFlash和NANDFlash混合设计的大容量、低成本存储系统的解决方案,并结合具体的开发环境,描述了该存储系统支撑软件的体系结构,最后给出了驱动软件的详细设计与实现方法。     

一种基于定制高性能互连的对象存储系统

基于高性能互连实现对象存储系统已经成为构建高性能计算机可扩展I/O系统的发展趋势。我们设计并实现了一种定制的高带宽、低延迟的高性能互连芯片HSNI,它提供了很好的通信性能,可用于构建对象存储系统。本文对HSNI的硬件体系结构、软件结构及其通信机制进行了介绍,并基于HSNI构建了高性能的对象存储系统。性能测试结果表明,HSNI芯片带宽高、延迟低,非常适合构建大规模对象存储系统,该存储系统能够很好地发挥Lustre系统的性能,并具有很好的可扩展性,能够很好地满足面向高性能计算的I/O系统需求。