基于NOR闪存的嵌入式数控系统文件系统设计*

设计了一个基于NOR闪存、面向嵌入式数控系统应用的文件系统TDNC-FS,给出了文件系统的层次化结构,详细分析了各个层次的功能和实现方法,特别对系统记录区的设计、空闲扇区的管理和flash扇区的均匀磨损的实现进行了深入研究,提出了具体的设计方法.     

Flash存储器的内建自测试设计

内建自测试是一种有效的测试存储器的方法.分析了NOR型flash存储器的故障模型和测试存储器的测试算法,在此基础上,设计了flash存储器的内建自测试控制器.控制器采用了一种23位的指令,并且通过JATG接口来控制,结果通过扫描链输出.验证结果表明,设计的内建自测试结构对固定故障、转换故障、桥接故障、耦合故障、栅极干扰、漏极干扰、过渡擦除和读干扰均有100%的故障覆盖率.     

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.     

容错智能IDE镜像磁盘系统的设计与实现

镜像磁盘以其可靠性高、相对简单且易于实现而广为采用。介绍了一个基于IDE接口的容错智能镜像磁盘糸统的设计与实现。提出并实现了镜像重组、镜像重构、镜像分区、操作系统无关性等一系列新思想,从而使得本系统具有普通镜像磁盘系统没有的功能特点。通过可靠性分析可知,本系统存储可靠性比普通镜像磁盘系统大为提高。     

基于IDE接口的容错智能镜像磁盘系统的研制

镜像磁盘以其可靠性高、相对简单且易于实现而广为采用。本文介绍了一个基于IDE接口的容错智能镜像磁盘系统的设计与实现,提出并实现了镜像重组、镜像重构、镜像分区、操作系统无关性等一系列新思想,从而使得本系统具有普通镜像磁盘系统没有的功能特点。最后通过可靠性分析得出本系统存储可靠性比普通镜像磁盘系统大为提高的结论。     

NAND flash的并行调度算法

通过对SSTF和SCAN等磁盘调度算法的分析,根据NAND flash的存储特性以及DMA的传输特性,提出一种兼容NVMHCI协议,结合时间相邻和空间相邻的快速调度算法.通过利用FPGA上的可配置处理器核,以定制指令形式成功实现了该调度算法.算法的性能在自行设计的存储系统中得到验证,存储系统的峰值吞吐量可以达到10Gbps.与类似存储系统相比,系统的灵活性和存储性能均有大幅提高.     

一种异构磁盘系统的数据分配方法

随着各种存储系统应用和技术的不断发展 ,出现了异构磁盘系统 .如果采用同构系统的数据分配和放置方法如 striping来管理异构系统 ,并不能针对异构系统中各个磁盘的性能差异来进行数据分配 ,降低了异构系统的性能 .提出了一种新的异构系统数据分配方法 .这种方法能够根据异构系统中磁盘的差异有效的进行数据分配 .它通过把系统中的磁盘划分成带宽相同的逻辑盘 ,并使用在同构系统中很成熟的 striping方法来对这些盘进行管理 ,实验证明这种方法能够有效的提高异构系统的吞吐率     

OFFS：基于对象模型的闪存文件系统研究*

提出了一种基于对象的存储系统管理框架,它使用统一的对象接口来访问flash或者磁盘。重点对基于对象模型的闪存文件系统进行了研究设计,在系统中引入了段的层次来进行对象管理,通过分析能够显著减少徘徊树问题引起的大量数据更新次数,并避免了垃圾回收时多余的I/O操作,缓解了垃圾回收过程中的数据锁定问题。     

磁盘驱动程序预写

较好地利用内存作为缓存,并优化磁盘设备的请求处理,是缓解系统I／O瓶颈的有效途径。提出一种驱动程序预写的方法来处理内存缓存中脏数据写回磁盘的方法,其基本思想是：通过将文件系统高速缓存中的脏数据写盘操作由磁盘设备驱动程序发起,磁盘可以在恰当的时间（设备空闲）或者恰当的位置（减少寻遣和设备旋转）完成写请求,减少缓存flush操作对当前应用的影响。模拟试验表明,谊方法能提高磁盘写操作的效率、系统数据的可靠性和系统的I／O性能。     

混合S-RAID:一种适于连续数据存储的节能数据布局

存储系统规模的日益增大,其高能耗成为一个无法忽视的问题,因此对存储系统的节能研究十分重要.提出一种由SSD固态盘与普通磁盘组成的混合S-RAID结构,通过关闭部分处于空闲状态的磁盘,达到节能效果.混合S-RAID将包括超级块在内的少量随机读写数据放在由SSD组成的RAID1中,将连续数据放在由普通磁盘组成的S-RAID中,S-RAID对磁盘分组,连续数据访问模式下只有一个组处于活动状态,关闭处于空闲状态的磁盘组.在仅增加少量成本的前提下,提高了存储系统的节能效果.混合S-RAID适用于各种以连续数据访问为主要特征的应用环境.实验表明,由12块普通磁盘和两块SSD固态盘组成的混合S-RAID 5与同级别RAID 5相比,能耗仅为RAID 5的28％.     

Reducing disk I/O times using anticipatory movements of the disk head

Finding a good rest position for the disk head is very important for the performance of a hard disk. It has been shown in the past that rest positions obtained through anticipatory movements of the disk head can indeed improve response time, but practical algorithms have not been described yet. In this paper we describe a software technique for perfoming anticipatory movements of the disk head. In particular, we show that by partitioning the disk controller memory into a part used for caching and a part used for predictive movements, lower I/O times as compared with the usual read-ahead cache configurations are obtained. Through trace-driven simulations we show in fact that significant improvements in the disk I/O times can be obtained as compared to standard disk caching. Since the technique should be realized at the firmware level in the disk controller and no hardware modifications are needed, the implementation cost is low.     

性能优化的双盘非同时故障容错布局分析

在分析双盘非同时故障容错模型的基础上,本文建议两种性能优化的布局：预留和约束的校验散布容错布局。当出现单盘故障后,这两种布局在不需要立即替换故障磁盘的情况 下自动过渡到另一个单磁盘故障容错的数据布局。约束的校验散布单盘故障布局便于提高校验写和单盘故障恢复性能,而且过渡算法实现较快。     

Arrangement of multi-dimensional scalable video data for heterogeneous clients

A scalable video server extracts data corresponding to the resolution requested by its client from the total data containing the information encoding a full resolution video. Depending on the requested resolution, the extracted data may not be contiguously placed on a disk or a disk array. For this reason, the traverse distance, which indicates the difference between the first read position and the last read position, can be much larger than the amount of the requested data. This causes additional rotational latency in a disk and thus degrades disk performance. Furthermore, scalable video data more seriously deteriorates the independency of disks in a disk array. That is, even a small read request can be split into multiple disk requests across disks of a disk array, because the requested data are scattered across multiple disks. To address these problems, we propose new data arrangement schemes for scalable video data. In these new schemes, we first deal with the arrangement of multi-dimensional scalable video data, which can be employed regardless of the number of scalability dimensions. Second, we improve disk performance by reducing average disk cost, which is based on both the traverse distance of each disk and the independency of disks. Third, we improve overall performance of disk devices through considering the entire request pattern, when large numbers of clients concurrently demand heterogeneous resolutions of videos from a server. We also propose fast arrangement algorithms to reduce the computation time required for searching an effective arrangement so that they can be easily applied to practical server system.     

Linux5．5安装U盘的制作与应用

用U盘安装win7操作系统已经相当普及,这是因为微软发布win7的同时发布了win7的安装u盘制作工具,使得u盘安装盘制作更为容易;而且u盘能重复使用,安装过程比光盘可靠而且速度快。但其他操作系统（如Linux）的u盘安装方法则很少报道,本文阐述制作1inux安装u盘的制作以及用u盘安装Read Hat Enterpro Linux5．5操作系统以及安装引导成功的关键事项。     

基于VC的U盘保密软件的设计及实现

U盘作为灵活的移动存储载体,广泛运用于各种终端间的数据传输.但普通U盘本身的安全性很难得到保障,容易成为病毒的载体,甚至导致不同程度的泄密.本文结合数据单向传输的特点,针对病毒查杀的滞后性,基于VC平台,设计并实现了一种U盘保密软件,可以在一定条件下保障U盘在电脑间传输数据时的安全性.     

A Statistical Admission Control Scheme for Continuous Media Servers Using Caching

In continuous media servers, disk load can be reduced by using buffer cache. In order to utilize the saved disk bandwidth by caching, a continuous media server must employ an admission control scheme to decide whether a new client can be admitted for service without violating the requirements of clients already being serviced. A scheme providing deterministic QoS guarantees in servers using caching has already been proposed. Since, however, deterministic admission control is based on the worst case assumption, it causes the wastage of the system resources. If we can exactly predict the future available disk bandwidth, both high disk utilization and hiccup-free service are achievable. However, as the caching effect is not analytically determined, it is difficult to predict the disk load without substantial computation overhead. In this paper, we propose a statistical admission control scheme for continuous media servers where caching is used to reduce disk load. This scheme improves disk utilization and allows more streams to be serviced while maintaining near-deterministic service. The scheme, called Shortsighted Prediction Admission Control (SPAC), combines exact prediction through on-line simulation and statistical estimation using a probabilistic model of future disk load in order to reduce computation overhead. It thereby exploits the variation in disk load induced by VBR-encoded objects and the decrease in client load by caching. Through trace-driven simulations, it is demonstrated that the scheme provides near-deterministic QoS and keeps disk utilization high.     

Analysis of the periodic update write policy for disk cache

A disk cache is typically used in file systems to reduce average access time for data storage and retrieval. The `periodic update' write policy, widely used in existing computer systems, is one in which dirty cache blocks are written to a disk on a periodic basis. The average response time for disk read requests when the periodic update write policy is used is determined. Read and write load, cache-hit ratio, and the disk scheduler's ability to reduce service time under load are incorporated in the analysis, leading to design criteria that can be used to decide among competing cache write policies. The main conclusion is that the bulk arrivals generated by the periodic update policy cause a traffic jam effect which results in severely degraded service. Effective use of the disk cache and disk scheduling can alleviate this problem, but only under a narrow range of operating conditions. Based on this conclusion, alternate write packages that retain the periodic update policy's advantages and provide uniformly better service are proposed     

A reliable optical disk identification technique for protection purposes

Optical disks are commonly used for distributing software applications and digital content. This article proposes a new technique to stop piracy. The proposed technique identifies the optical disk and differentiates between the original disk and its copies. It can be used for software protection in order to provide strong security with a reliable performance. The proposed technique models and simulates the entire optical disk system in order to study the effect of physical differences between original disks and copies. The physical parameters of the original disks can be controlled while manufacturing; however, the parameters of the copies are constant. System simulations are performed to study the variations of disk parameters, drive configuration, and operating conditions. Further, practical experiments are conducted inside the lab to verify the simulation results. Finally, thousands of actual experiments are conducted to optimize the system performance and to decrease the failure rate.     

Position error reduction in magnetic disk drives using a head gimbal assembly with radial head motion capability

Reducing the head positioning error is important to achieve higher track density in hard disk drives. In this paper, it is shown that the head off-track due to disk vibration can be reduced by using a head gimbal assembly capable of moving not only vertically to disk surface but also radially across the track. We find the optimal geometric relationship to minimize the head off-track due to disk vibration. The relationship is obtained based on precise mathematical modeling of head off-track mechanism due to disk vibration. Some examples of head gimbal assembly (HGA) with radial head motion capability, which satisfy such optimal relationship, are also proposed. It is experimentally found that the proposed optimal HGA can reduce non-repeatable run-out (NRRO) position error signal (PES) significantly. Since it reduces NRRO PES during servo track writing as well, the written-in portion of repeatable run-out PES can be also significantly reduced.