网络RamDisk的设计与实现

在当前计算机产业中,有效的数据存储通常还是由磁盘来实现的.现在,磁盘传输速度不断改善,但远没有微处理的速度增加快,因此,磁盘存取的代价相对于处理器来说,变得越来越大.本文设计并实现一个网络RamDisk,其主要思想是利用远地空闲PC机的内存,来作为一个比本地磁盘快的存储设备.我们的网络RamDisk是在Linux操作系统下,作为一个块设备驱动程序来实现的,因此,不需要修改任何Linux系统的内核代码.我们使用了一些应用程序进行测试,获得了较好的性能.     

程序用上RamDisk 速度立马升10倍

在Vista中微软应用了ReadyBoost和Windows SuperFetch两项新内存技术,其中Windows SuperFetch是将你最常用的应用程序预加载到内存中以便进行快速访问。其实,Windows早期的RamDisk(内存盘)就是与此功能类似,它能将一部分内存空间模拟成一个硬盘分区。由于系统内存的存取速度远快于硬盘速度,所以对于频繁磁盘存取的应用程序(例如数据库程序、磁盘文件交换程序、网站服务程序等),使用RamDisk能有效地提高其性能。但是,很多朋友不知道怎么利用RamDisk加快程序的速度,下面我们为大家用RamDiskXP举几个例子:     

基于LVM 的系统扩容技术研究

近年来,随着大数据业务的使用,系统在运行时会产生大量的数据信息与日志文件并保存在磁盘中。由于在系统规划初期,对系统分区大小规划预期不足,很难合理规划磁盘空间,造成后期系统运行中经常出现系统分区磁盘不足的问题。当发生此类告警时,通常的分区很难动态调整大小,通常采用暂停业务,更换磁盘,数据备份与恢复的方式,该方式操作困难,程序复杂,有数据丢失的风险。在Linux系统里使用LVM(逻辑卷)技术,支持在线空间扩容,可以在用户无感知的情况下扩展系统分区容量,达到合理利用磁盘空间的目的。本文介绍了LVM技术,并在Linux系统里将分区做成逻辑卷,达到合理利用磁盘空间的目的。     

基于LSM的网络日志信息提取的实现

LSM（Linux Security Modules）是由Linus Torvalds本人提出来的一个非常灵活的安全策略的底层架构。其采取什么样的安全策略完全是由用户自己决定。本文主要阐述了在LSM框架这上基于操作系统网络部分日志信息提取的实现，以及对在这个过程中发现的LSM的缺陷进行分析和讨论。     

利用LKM记录键盘事件的研究与实现

Linux作为自由软件,提供了更多的灵活性和开放性。利用这一优点,我们可以增强Linux系统的安全性。本文首先介绍了 LKM　(Loadable　Kernel　Modules,可加载内核模块)的概念及其原理,然后详细阐述了 Linux下键盘驱动程序的工作原理,最后实现了LKM,来记录本地用户和远程登录到本系统的用户敲击键盘行为,为系统安全提供了一项重要的日志来源。     

多Markov链预取模型在网络内存系统中的应用

主机通过高速网络访问远程内存的性能已经达到或远高于访问本地磁盘的性能，通过各种优化手段，网络内存系统的性能能得到更好的提升。该文基于一个Linux网络内存系统(LNMS)，在客户端一级提出了一种新的预取算法m-ppm，该算法发展了多Markov链预取模型，使之更适合LNMS。在LNMS上实现了另2种常用的预取算法以作比较，实验数据表明，m-ppm算法对多用户模式更有效。     

基于Linux网络块设备和软RAID技术的网络镜像

Linux网络块设备和软RAID技术的网络镜像(LNRM)系统实现的关键技术是软RAID和网络设备结合通过网络来镜像整个设备或分区，可把它作为一种网络RAID。Linux下的网络块设备是把网络访问的远程资源虚拟成一个本地块设备，是一种数据异地透明存取的网络存储技术，是实现海量数据网络存储的新方法。该文探讨了块设备和软RAID的原理，分析了网络块设备作为网络RAID阵列的优势，给出了基于Net_RAID技术的网络镜像在Linux环境下的设计和实现，同时也为系统共享网络资源提供一种可选择的手段。     

NAS设备的磁盘调度模型分析

附网存储 (NAS)设备的性能目标是优化网络存储数据访问和存储子系统的管理 .本文旨在显示随着磁盘转速的增加 ,NAS应该从磁盘硬件的最佳工作性能出发 ,整体配合以提高它的 I/O操作性能 .为了发掘 NAS最佳的工作性能 ,我们建立同时基于磁臂位置和旋转位置的精确的磁盘调度模型 ,并提出测量调度算法性能的方法 .以 HP975 6 0性能参数为基础 ,进行理论分析和模拟测试 .结果磁盘转速越快 ,磁盘访问的开销越大 .因此 ,NAS设备的设计必须从整体上考虑磁盘调度策略的选择 ,并行多磁盘结构的选择 ,文件 cache的分配和文件系统布局等 ,以便提高网络存储数据访问的性能     

机群全局资源管理的SSI研究

机群的主要系统资源是处理器、内存和磁盘,为实现全局资源管理的单一系统映像,文中介绍了与之有关的关键技术:分布式存储器管理、全局磁盘管理和全局处理器管理。为实现上述功能,文中提出了采用容器技术来实现分布资源管理的策略,此技术已在Linux操作系统的内核层中实现。     

Linux是否后来居上

虽然目前采用嵌入式Linux手机操作系统的产品在市场中所占的市场份额还很小,远不及PalmOS、Symbian和WindowsCE操作系统。虽然据有关市场预测,即使是到了2006年,Linux手机操作系统也将只占到整个市场份额的4.2%。但我们却不能忽视Linux在手机领域的发展潜力。当手机作为一种智能终端,来实现当前PC、PDA等业务应用时,将加速linux手机操作系统的发展。如果说linux的发展主要源于其源代码的开放,那么Linux这种先天的优势决定了它比专有手机操作系统成本更低,设备提供商更容易在上面进行功能及应用的开发,因此也更易被用户所接受。当时采…     

Storage allocation policies for time-dependent multimedia data

Multimedia computing requires support for heterogeneous data types with differing storage, communication and delivery requirements. Continuous media data types, such as audio and video, impose delivery requirements that are not satisfied by conventional physical storage organizations. In this paper, we describe a physical organization for multimedia data based on the need to support the delivery of multiple playout sessions from a single rotating-disk storage device. Our model relates disk characteristics to the different media recording and playback rates and derives their storage pattern. This storage organization guarantees that as long as a multimedia delivery process is running, starvation will never occur. Furthermore, we derive bandwidth and buffer constraints for disk access and present an approach to minimize latencies for non-continuous media stored on the same device. The analysis and numerical results indicate the feasibility of using conventional rotating magnetic disk storage devices to support multiple sessions for video-on-demand applications     

一种新型网络视频点播的存储层次

针对多媒体应用中快速存储资源上对匮乏和磁盘速度受限问题,实现了使用网络空闲内存资源作为快速设备缓冲媒体的机制,扩展了多媒体环境中的存储层次,并给出了一种简单快速的cache替换算法,初步结果表明,该机制可以加速多媒体环境中存储数据的访问速度。     

Real time servo control of the holographic data storage system with an additional servo beam

Holographic data storage is a next generation data storage device, which has high storage density, high data transfer rate and short access time. The device is very sensitive to disturbances due to its enormous storage density. In the disk type holographic data storage device deviation occurs successionally on the position of the data as the disk rotates. Therefore the spot where the probe beam is illuminated should directly be corrected in order to exactly retrieve the desired data. In this paper we suggest a method using an additional beam containing a servo pattern in order to detect the deviation of the media. We also propose a real time servo control method to compensate the affect of the unpredicted disturbance.     

HybridPlan: a capacity planning technique for projecting storage requirements in hybrid storage systems

Economic forces, driven by the desire to introduce flash into the high-end storage market without changing existing software-base, have resulted in the emergence of solid-state drives (SSDs), flash packaged in HDD form factors and capable of working with device drivers and I/O buses designed for HDDs. Unlike the use of DRAM for caching or buffering, however, certain idiosyncrasies of NAND Flash-based solid-state drives (SSDs) make their integration into hard disk drive (HDD)-based storage systems nontrivial. Flash memory suffers from limits on its reliability, is an order of magnitude more expensive than the magnetic hard disk drives (HDDs), and can sometimes be as slow as the HDD (due to excessive garbage collection (GC) induced by high intensity of random writes). Given the complementary properties of HDDs and SSDs in terms of cost, performance, and lifetime, the current consensus among several storage experts is to view SSDs not as a replacement for HDD, but rather as a complementary device within the high-performance storage hierarchy. Thus, we design and evaluate such a hybrid storage system with HybridPlan that is an improved capacity planning technique to administrators with the overall goal of operating within cost-budgets. HybridPlan is able to find the most cost-effective hybrid storage configuration with different types of SSDs and HDDs     

Highly available and heterogeneous continuous media storage systems

A number of recent technological trends have made data intensive applications such as continuous media (audio and video) servers a reality. These servers store and retrieve large volumes of data using magnetic disks. Servers consisting of multiple nodes and large arrays of heterogeneous disk drives have become a fact of life for several reasons. First, magnetic disks might fail. Failed disks are almost always replaced with newer disk models because the current technological trend for these devices is one of annual increase in both performance and storage capacity. Second, storage requirements are ever increasing, forcing servers to be scaled up progressively. In this study, we present a framework to enable parity-based data protection for heterogeneous storage systems and to compute their mean lifetime. We describe the tradeoffs associated with three alternative techniques: independent subservers, dependent subservers, and disk merging. The disk merging approach provides a solution for systems that require highly available secondary storage in environments that also necessitate maximum flexibility.     

附网光盘刻录设备运行品质参数模型与仿真

附网光盘刻录设备兼具网络存储和光存储的优点，提供方便的低成本远程数据备份，并且具有良好的扩充性，但基于分组交换原理的网络数据流量的不稳定直接威胁光盘刻录设备的运行品质．通过排队理论分析和数学模型仿真，定量地研究了在不同的网络负栽环境下，附网光盘刻录设备的Cache容量及使用策略对其运行品质的影响，最后针对不同的使用环境，提出了具体的提高附网光盘刻录设备运行品质参数的方法．     

基于可信平台模块的虚拟单调计数器研究

分析了存储中常见的重放攻击问题,提出一种基于可信平台模块TPM构造虚拟单调计数器的方案以阻止重放攻击.该方案基于TPM提供的硬件计数器、传输会话与私钥保护3种机制建立起虚拟计数器管理器(virtual counter manager,VCM),再由VCM构造和管理虚拟单调计数器.同时提出了一种VCM恶意行为检测算法,用以确保VCM的可信性,使得该方案的安全性仅依赖于TPM的防篡改性.最后,通过实验分析,提出了2个性能改进方案,以确保方案的可行性.     

Ring Delay Chain for Exact Measure of Pulse Cycle Error

This paper introduces a new method named a ring delay chain for exact measure of pulse eycle error.This method can measure a few nanoseconds' error and does not need any high frequency device.Applicationof this method has obtained very good result in a pilot equipment having a servo surface for magnetic diskstorage.     

磁道复制--多媒体数据读取的磁盘寻道优化策略

由于寻道是磁盘I／O操作中的主要浪费之一,采用磁道复制可以减少寻道．针对单盘与盘阵情况,磁道复制可以有两种不同的方法：n-way和n-d-way,并经推导可得出二者平均寻道距离的解析表达式.进行的模拟实验不仅证明了解析表达式的准确性,而且表明在相同的空间开销下,磁道复制策略比传统的以空间换取时间的策略如n-way striping和D-way mirror有更少的寻道距离．