复本存储机制的效率研究

建立独立于具体算法的复本存储模型,识别影响效率的关键参数和无关参数;分析系统规模增长对效率的影响,通过实验得出空间效率与I/O效率的乘积同系统节点数量近似成反比这一结论,并从理论上解释结论背后的成因。研究结果可用于指导复本存储机制的工程应用,为空间效率和I/O效率之间的权衡以及大规模存储系统I/O性能的预测提供理论依据。     

自适应电话网关的网络存储系统

基于目前解决存储瓶颈的各种技术受到各环节性能极限的约束,本文提出的自适应网络存储系统采用设计独特的可扩展双通道存储体系结构,综合利用各种I／O技术,解决了I／O密集型应用的存储瓶颈。     

融合NAS和SAN的存储网络设计与实现

针对目前两种主流网络存储系统存在的缺陷,本文提出和实现了一种在IP协议下融合NAS和SAN的统一存储网络系统.通过全局多协议文件系统,统一存储网络能同时支持文件协议和块协议,实现了NAS设备和SAN设备在IP上的无缝融合,满足了应用开放性、高扩展和海量存储的需求;通过iSCSI软件实现模块,统一存储网络能同时为客户提供文件I/O和块I/O服务,具有NAS和SAN二者的优点;通过自主存储代理文件系统,统一存储网络能同时通过服务器通道或高速附网通道向客户机提供数据,提高了系统的I/O响应速度,减少了服务器瓶颈.实验结果显示,统一存储网络系统具有超高速的文件I/O和块I/O响应速度,能为网络提供性能、扩展性、兼容性、性价比都更好的海量存储系统.     

一种面向边缘计算的可扩展网络I/O框架

作为当前的研究热点,边缘计算可以在网络边缘部署计算、存储和网络资源,为用户提供云化服务,以满足新兴应用的处理需求。但是,当前网络I/O模型的扩展性问题使得运行在边缘节点上的边缘应用难以有效地利用丰富的边缘物理资源处理海量用户的网络请求。针对边缘计算场景下网络I/O模型的数据竞争和负载不均衡问题,提出了一种新的可扩展网络I/O模型。通过试验可以看出,利用该模型的边缘应用具有良好的性能和可扩展性。     

扩展I/O通道的存储连接技术

在简要分析传统的SCSI技术的基础上,对扩展I／O通道的新连接技术进行了研究。光纤通道技术提供了很高的I／O性能,但容易形成SAN“孤岛”。iSCSI将SCSI与以太网技术结合,将多个SAN“孤岛”连接在一起。InfiniBand用通用的适配器综合各类存储设备,在I／O性能和扩展性等方面都极具吸引力。该文重点研究了RDMA的结构、特征及在存储中的应用,它引入了零复制概念,使主机端的I／O瓶颈被打破,在网络存储中有着广泛的应用前景.     

网络分布式文件系统NDFS的设计与实现

分布式文件系统能够有效地解决分布式系统中海量数据存储和I/O瓶颈问题,分布式文件系统是任何大规模分布式计算环境的重要组成部分,它的性能直接影响着整个分布式计算环境的执行效率.通过系统地研究分布式文件系统性能建模中的若干关键技术,在服务器Linux操作系统中加入一个新的文件系统模块,该模块采用存储虚拟化技术使Linux服务器上的应用软件可以透明的使用网络上的数据文件资源,并且对这些分布式的文件通过软件RAID方式实现了数据冗余,保证存储的可靠性,并通过并行存取提高I/O吞吐率.     

数据筛选技术在并行I/O中的应用

Collective I/O是并行I/O的一种实现方式,然而科学应用中的请求并不总能很好地满足进行Collective I/O的前提条件.根据工作站网络的特点,在并行I/O系统CION(Collective I/O on Now system)中将数据筛选技术与之紧密结合,充分发挥了Collective I/O的功效.性能测试显示了数据筛选对系统性能的显著提高.     

多路径I/O技术在电视台SAN存储网络中的应用探讨

本文以电视台非编制作网SAN存储网络为应用背景,从多路径I/O技术的原理出发,对多路径I/O的实现方式进行分析,重点介绍不同类型存储设备多路径I/O的故障切换和负载均衡方式,并针对电视台SAN存储网络的特点,从高效性、可靠性和经济性方面对多路径I/O技术在电视台SAN存储网络中的应用做一些探讨.     

基于IP的高可用海量网络存储系统的研究

提出和实现了一种在IP下融合NAS(附网存储)、SAN(存储区域网)和对象存储技术的高可用海量网络存储系统(MNSS,mass network storage system)。在MNSS中通过统一多协议文件系统,实现了NAS设备、SAN设备和对象存储设备在IP上的融合,满足了应用开放性、高扩展和海量存储的需求;通过iSCSI软件模块,MNSS对存储资源提供统一的管理和优化,同时提供文件I/O和块I/O服务,使MNSS同时具有NAS和SAN的优点;通过自主存储代理模块,MNSS能同时提供服务器通道和附网高速通道,改善了系统的I/O性能,减少了服务器瓶颈;通过高可用系统设计,MNSS能为数据和应用提供更高的可用性,满足了企业高可用的存储需求。实验结果显示,MNSS有超高速的文件I/O和块I/O响应速度,能为网络提供高性能、高扩展性的对象存储设备,高可用性、高性/价比的海量存储系统。     

基于PC集群的SAN存储系统性能优化方法

对于早期的中低端SAN存储系统,由于受当时的技术局限,目前已经无法满足日益增长的海量数据高速传输的要求。介绍了SAN存储系统性能优化方法,可以提高PC集群SAN存储系统的网络和I/O带宽,较好地解决了PC集群系统I/O瓶径问题;对于增强存储系统的长效性、稳定性和数据访问效率起到关键作用。     

Rabb et: Using Layout-Aware Backup for RAID Reconstruction

Once a disk of storage system is failed, RAID mechanism will reconstruct to keep the reliability. The reconstruction leads to a sharp deterioration in I/O performance of RAID, and the storage system cannot pro-vide high performance service for the applications. The Multi-TB disk capacity and high load of the application make the reconstruction last for a very long time. This paper proposes Rabbet, a method accelerating RAID re-construction using data of backup. Rabbet includes a new RAID reconstruction frame, a RAID layout-aware map-ping mechanism for backup, and a reconstruction algo-rithm. The result of experiments shows that, comparing to the classic DOR methods Rabbet shortens the RAID5 reconstruction process to 13.9%–42.8% and decreases the average response time for applications during reconstruc-tion by 3.2%–14.6%. Rabbet also improves the reliability of storage systems.     

RAID系统扩容方案研究综述

随着云计算、物联网和人工智能等IT技术驱动数字经济产业的繁荣发展,现代企业信息化需求对数据中心存储能力提出了更高的要求和挑战.RAID系统因具备良好的数据存储可靠性和磁盘阵列可扩展性而得到广泛应用.为了满足海量数据对存储容量日益增长的需求,业界普遍采用扩容现有RAID系统以应对海量数据的存储问题.电子商务、Web服务和金融等行业对数据的实时访问,使得数据中心必须为用户提供7*24的高质服务响应,然而数据迁移量,负载均衡和扩容开销等因素都会影响扩容的效率,因此如何设计出一种高效的扩容方案越来越受到科研人员的关注.本文根据研究对象的不同将RAID扩容方案分为：基于块存储、对象存储、文件系统存储的扩容方案,同时根据RAID扩容方案研究历程和优化策略的不同,又可分为优化数据迁移过程和减少数据迁移量的扩容方案.文章结合不同的应用场景介绍了典型和常见的扩容方案,并从评价扩容方案性能各项重要指标的角度详细分析了现有的RAID扩容方案,并指出各种扩容方案的不足以及未来可能的发展方向.如何权衡影响扩容方案性能的各项因素,设计出数据迁移少,负载均衡好,扩容开销低的高效扩容方案,将会是今后相当长一段时间海量数据存储研究的热点问题.     

An efficient management scheme for updating redundant information in flash-based storage system

Since flash memory has many attractive characteristics such as high performance, non-volatility, low power consumption and shock resistance, it has been widely used as a storage media in embedded and computer system environments. However, there are many shortcomings in flash memory such as potentially high I/O latency due to erase-before-write and poor durability due to limited erase cycles. To address these performance and reliability anomalies, many large-scale storage systems use redundancy-based parallel access schemes such as RAID techniques. However, such redundancy-based schemes incur high overhead due to generating and storing redundancy information, especially in flash-based storage systems. In this paper, we propose a novel and performance-effective approach using a redundancy-based data management scheme in flash storage, called Flash-aware Redundancy Array. The proposed technique not only reduces the redundancy management overhead by performing redundancy update operations during idle periods, but also provides a preventive mechanism to recover data from unexpected read errors occurring before such redundancy update operations finish. From the experiments, we found that the proposed technique improves flash-based storage systems by 19% in average execution time as compared to other redundancy-based approaches.     

带Cache的磁盘阵列I/O响应时间及吞吐量分析

文章分析了磁盘参数的描述,针对华中科技大学研制的磁盘阵列,利用排队论分析并计算带Cache磁盘阵列I/O响应时间及吞吐量,得出了提高I/O平均响应时间及最大吞吐量的方法。     

Response Time Analysis on Multicore ECUs With Shared Resources

As multiprocessor systems are increasingly used in automotive real-time environments, scheduling and synchronization analysis of these platforms receive growing attention. Upcoming multicore ECUs allow the integration of previously separated functionality for body electronics or sensor fusion onto a single unit, and allow the parallelization of complex computations over multiple cores. The application of multiple CPUs turns an ECU into a highly integrated “networked system” microcosm, in which complex interdependencies can be observed due to the use of shared resources even in partitioned scheduling. To deliver predictable performance, resource arbitration protocols are required and have been proposed in literature. This paper presents an novel analytical approach to provide the worst-case response time for real-time tasks in multiprocessor systems with shared resources. The method supports realistic, event- or time-driven task activation schemes and allows to calculate tight bounds on the estimated system performance.      

Eco-Storage: A Hybrid Storage System with Energy-Efficient Informed Prefetching

In this paper, we present an energy-aware informed prefetching technique called Eco-Storage that makes use of the application-disclosed access patterns to group the informed prefetching process in a hybrid storage system (e.g., hard disk drive and solid state disks). Since the SSDs are more energy efficient than HDDs, aggressive prefetching for the data in the HDD level enables it to have as much standby time as possible in order to save power. In the Eco-Storage system, the application can still read its on-demand I/O reading requests from the hybrid storage system while the data blocks are prefetched in groups from HDD to SSD. We show that these two steps can be handled in parallel to decreases the system’s power consumption. Our Eco-Storage technique differs from existing energy-aware prefetching schemes in two ways. First, Eco-Storage is implemented in a hybrid storage system where the SDD level is more energy efficient. Second, it can group the informed prefetching process and quickly prefetch the data from the HDD to the SSD to increase the frequent HDD standby times. This will makes the application finds most of its on-demand I/O reading requests in the SSD level. Finally, we develop a simulator to evaluate our Eco-Storage system performance. Our results show that our Eco-Storage reduces the power consumption by at least 75 % when compared with the worst case of non-Eco-Storage case using a real-world I/O trace.     

硬盘测试软件设计与测试

硬盘作为计算机中存储数据的主要载体,其性能的好坏直接决定着整个计算机系统性能的高低.本文设计实现了一种硬盘测试软件,主要模拟硬盘实际I/O读写情况,发出读操作命令,然后统计、计算测试过程中的各个参数指标值.测试的性能参数包括：瞬时、平均、最大数据传速率,平均、最大读操作响应时间,读操作次数,读错误次数及CPU占用率等.分析测试结果知,在硬盘基本性能参数测试时,顺序读操作测试的硬盘瞬时数据传输率随着读操作数据块的增加先增大后减小;随机读操作比相应数据块大小的顺序读操作的数据传输率小.模拟测试流媒体文件服务时,多用户的总数据传输率比单用户时的数据传输率要小得多.     

Web-conscious storage management for Web proxies

Many proxy servers are limited by their file I/O needs. Even when a proxy is configured with sufficient I/O hardware, the file system software often fails to provide the available bandwidth to the proxy processes. Although specialized file systems may offer a significant improvement and overcome these limitations, we believe that user-level disk management on top of industry-standard file systems can offer similar performance advantages. We study the overheads associated with file I/O in Web proxies, we investigate their underlying causes, and we propose Web-conscious storage management, a set of techniques that exploit the unique reference characteristics of Web-page accesses in order to allow Web proxies to overcome file I/O limitations. Using realistic trace-driven simulations, we show that these techniques can improve the proxy's secondary storage I/O throughput by a factor of 15 over traditional open-source proxies, enabling a single disk to serve over 400 (URL-get) operations per second. We implement Foxy, a Web proxy which incorporates our techniques. Experimental evaluation suggests that Foxy outperforms traditional proxies, such as SQUID, by more than a factor of four in throughput, without sacrificing response latency.     

QoS-based remote control of networked control systems via Profibus token passing protocol

This paper focuses on a quality-of-service (QoS)-based remote control scheme for networked control systems via the Profibus token passing protocol. Typically, token passing experiences random network delay due to uncertainties in token circulation, but the protocol has in-built upper and lower bounds of network delay. Thus, to ensure the control performance of networked control systems via the Profibus token passing protocol, the network delay should be maintained below the allowable delay level. As the network delay is affected by protocol parameters, such as target rotation time, we present here an algorithm for selection of target rotation time using a genetic algorithm to ensure QoS of control information. We also discuss the performance of the QoS-based remote control scheme under conditions of controlled network delay. To evaluate its feasibility, a networked control system for a feedback control system using a servo motor was implemented on a Profibus-FMS network.