一种基于3容错阵列码的RAID数据布局

在EVENODD码的基础上,提出一种新的基于EEOD码的RAID数据布局,只需要3个额外的磁盘保存校验信息,能容许任意3个磁盘同时故障,并给出了EEOD的代数定义,理论上证明了EEOD码的MDS性质.从一种新的途径讨论了EEOD码的译码过程:用图的回路表示通过"异或"运算得到的校验方程组,把译码过程归结为图回路的叠加,进而校验方程组图中度为偶数的顶点逐步消除.讨论了基于EEOD码阵列布局的性能,与其它RAID结构相比,容灾能力大幅度提高,编码和译码过程只需要简单的异或运算,但是空间利用率影响非常小,并且EEOD具有很好的性能,具有很好的应用前景.     

一种高可用对象存储系统的数据组织研究

通过对现有不同存储系统的容错能力进行认真分析,提出了一种新的高可用对象存储系统架构HAOSS(High Availability Object Storage System).HAOSS系统分两层:上层存储的对象采用在多个设备之间的数据备份的方式来实现高可靠性,多个备份能够同时对外提供服务,保证系统的高性能,但是磁盘利用率比较低.下层采用RAID5,RAID6以及RAID_Blaurn等不同的容错编码来实现多盘容错功能,磁盘利用率较高,但是由于编码越来越复杂,容错编码需要大量的计算,性能受到很大的影响.在数据组织上,新对象和热点对象放上层,这样大部分请求都能够在上层命中,从而保证系统的性能.下层主要用来放不常用的数据.磁盘利用率比较高.在1000Mbps以太网环境下对HAOSS性能进行了测试,结果表明,HAOSS顺序读写性能都比较好,最大可以达到104MB/s,达到1000Mb以太网的理论最大物理带宽.     

基于奇偶校验的三容错数据布局研究

基于单容错编码的数据布局已经不能满足存储系统对可靠性越来越高的要求。对基于多容错编码的数据布局的研究受到了广泛的关注,并且出现了一些三容错的布局算法,如HDD1,HDD2等。但这些布局算法普遍存在冗余度较差、计算负载大等缺点。提出了一种基于三重奇偶校验的多容错数据布局算法TP-RAID(Triple Parity RAID)。该算法只需要在RAID5阵列系统中增加两个校验磁盘,通过水平、正向对角和反向对角三重奇偶校验,可容许同时发生的三个磁盘故障。该算法编码、解码简单,三重校验条纹长度相等,计算负载小,易于实现。此外,由于该算法中尽量减少了三重校验之间逻辑关联,使得该算法的小写性能比其他的三容错算法相比有了大幅度的提高。     

RAID技术研究

计算机的发展,对信息的存储技术提出了更高的要求。但是磁盘的I／O性能始终成为提升的瓶颈。为了解决这一问题．提出了RAID阵列。RAID阵列采用数据分块技术,在多个磁盘上交叉存储使得多盘可平行操作,I／O响应时间得到改善．同时利用冗余容错技术,极大提高了磁盘阵列的可靠性和安全性。     

在FreeBSD下使用Vinum创建和管理软RAID阵列

RAID为冗余磁盘阵列的简称，他意味着物理上使用多个磁盘，而逻辑上却只有一个磁盘设备。然而，RAID技术中包含的技术又远远超过简单的将多个磁盘映射到一个虚拟磁盘设备上的技术，它提出了使用几种不同方式来完成这种工作。关键是RAID通过使用数据冗余带来额外的数据安全性，     

认识几种不常见RAID等级

RAID15、RAID51和RAID100是在存储架构中出现的一些新型的R A I D阵列,它们和我们日常使用的RAID阵列之间有很大的差别,他们有很多的优点,但是它们的造价也非常昂贵。RAID15(奇偶位镜像阵列,或者先进行RAID1再进行RAID5)最大容量([磁盘数量/2)-1]x磁盘容量描述所需的驱动器数量(最少):6(要求磁盘数量为偶数)优点你想要让你的数据获得真正的安全,完全不必担忧磁盘故障吗?可以试试RAID15或者RAID51。它们都提供了超强的容错能力。即使大量磁盘损坏的情况下仍然不会丢失数据。但是容错能力取决于出现故障的是哪一块磁盘。如果…     

自修复磁盘阵列技术研究

以数据为中心的计算模式对数据的可靠性提出新的需求,高可靠存储设备成为高性能计算的基础.自从Xiotech公司提出ISE结构并取得成功后,关注磁盘失效之前的征兆而不是失效后的具体处理的"自修复"概念已成为磁盘阵列设计新的指导思想之一.提出存储系统可靠性系数的概念,分析单个磁盘可靠性与磁盘阵列可靠性关系,选择合适的磁盘S.M.A.R.T属性结合磁盘当前利用率和历史信息建立评定磁盘状态的T~2US算法,接着介绍RAID 5结合T2US监测的高可靠、自修复的RAID 5T结构,说明RAID 5T结构的运行方式和磁盘不符合T~2US监测标准时数据迁移策略,最后对结构的可靠性利用存储系统可靠性系数和MTTF分别进行了分析.     

RAID如何选

所谓磁盘阵列,就是利用多个硬磁盘,来提高存取速度、将磁盘故障时的危害降低到最低限度的机构。磁盘阵列也叫 RAID,原本是在大型计算机中,使用多个廉价小型(5.25或3.5 inch)磁盘来扩大磁盘容量的。RAID 根据数据的分散方法和冗余数据的生成/记录方法,定义成0～5级6种。现在,主要使用的是RAID0、1、3、5(见表).RAID0是一种以块为单位将数据分散记录在多个磁盘上,也叫磁盘分条。由于对于多个磁盘可以并行读写数据,所以比起一台磁盘来,读/写性能都得到了显著提高。但用 RAID0不能提高抗故障能力。譬如说,用2台磁盘构成 RAID0,数据分散记录在2台磁盘上,但只要有一个磁盘发生故障,数据就全部丢掉     

虚拟机Windows 10的软RAID配置与恢复

磁盘阵列(RAID)具有提高计算机读写数据的速度、实现对数据的冗余保护及保证数据存储可靠性的功能.本文介绍利用在虚拟机Windows 10客户机添加两个磁盘进行软件RAID的配置,以及模拟磁盘损坏和RAID1恢复的方法.该方法中的RAID1可以保证普通用户数据存储的可靠性,适用性强.     

RAID路在脚下

如果你的工作是提高服务器的可用性、改进服务器性能或者实时备份数据,则RAID应在你的计划中占一席之地。RAID的优势在于其灵活性。你可以先确定要实现的目标的优先等级,如连续工作时间、数据保护、I/O速度和成本等,然后对系统进行配置以满足你的需求。数字意味什么? 购买RAID系统时,最重要的是要看它所支持的RAID级别。“级别”一词在此容易产生误解,使人感觉好象在表示一个分层结构,然而第2级并不一定比第1级好。 RAID 0不提供任何冗余,因此不能提供真正的数据保护,所以也不是真正的RAID。在RAID 0中,数据被分为许多块,并被写入不同磁盘。写操作所用时间与将数据写入单一磁盘所需时间相同。但是当用户请     

A multiple disk failure recovery scheme in RAID systems

In this paper, we propose a practical disk error recovery scheme tolerating multiple simultaneous disk failures in a typical RAID system, resulting in improvement in availability and reliability. The scheme is composed of the encoding and the decoding processes. The encoding process is defined by making one horizontal parity and a number of vertical parities. The decoding process is defined by a data recovering method for multiple disk failures including the parity disks. The proposed error recovery scheme is proven to correctly recover the original data for multiple simultaneous disk failures regardless of the positions of the failed disks. The proposed error recovery scheme only uses exclusive OR operations and simple arithmetic operations, which can be easily implemented on current RAID systems without hardware changes.     

RAID0.5: design and implementation of a low cost disk array data protection method

RAID has long been established as an effective way to provide highly reliable as well as high-performance disk subsystems. However, reliability in RAID systems comes at the cost of extra disks. In this paper, we describe a mechanism that we have termed RAID0.5 that enables striped disks with very high data reliability but low disk cost. We take advantage of the fact that most disk systems use offline backup systems for disaster recovery. With the use of these offline backup systems, the disk system needs to only replicate data since the last backup, thus drastically reducing the storage space requirement. Though RAID0.5 has the same data loss characteristics of traditional mirroring, the lower storage space comes at the cost of lower availability. Thus, RAID0.5 is a tradeoff between lower disk cost and lower availability while still preserving very high data reliability. We present analytical reliability models and experimental results that demonstrate the enhanced reliability and performance of the proposed RAID0.5 system.     

基于智能预警的自恢复存储系统研究

为提高磁盘阵列存储的可靠性,提出一种基于智能预警的自恢复存储系统。在对磁盘S.M.A.R.T信息实时监测采集的基础上,利用机器学习方法对磁盘故障进行预测,对于预警磁盘采取以数据为中心的自修复迁移保护策略。分析结果表明,该系统能提高存储可靠性,数据迁移过程对用户透明,可用性较强。     

X-code double parity array operation with two disk failures

X-code extends parity coding for correcting single disk failures in RAID 5 to two disks. Similar to RAID 6 X-code uses the minimum level of redundancy by dedicating the capacity of two out of N disks to check disks, but unlike RAID 6 it solely relies on parity codes, which are placed horizontally rather than vertically. The parity groups in X-code are defined as diagonals with positive and negative slopes. This study is mainly concerned with X-code arrays with two disk failures, since it requires a multistep recovery process, while its operation is otherwise similar to RAID 6. We use examples to gain insight into the cost of recovery and to develop an algorithm to estimate recovery cost for reconstructing two failed disks. We observe that disk loads are unbalanced and the overall load increase depends on the separation of the failed disks. Cyclically shifting or randomly permuting successive N×N arrays of blocks may be used to reduce the load increase to the mean across all of the possible (N−1)/2 distances of the failed disks. We also present an improvement in recovery cost for single disk failures.     

Segmented information dispersal (SID) data layouts for digitalvideo servers

We present a novel data organization for disk arrays-segmented information dispersal(SID). SID provides protection against disk failures while ensuring that the reconstruction of the missing data requires only relatively small contiguous accesses to the available disks. SID has a number of properties that make it an attractive solution for fault-tolerant video servers. Under fault-free conditions, SID performs as well as RAID 5 and organizations based on balanced incomplete block designs (BIBD). Under failure, SID performs much better than RAID 5 since it significantly reduces the size of the disk accesses performed by the reconstruction process. SID also performs much better than BIBD by ensuring the contiguity of the reconstruction accesses. Contiguity is a very significant factor for video retrieval workloads, as we demonstrate. We present SID data organizations with a concise representation which enables the reconstruction process to efficiently locate the needed video and check data     

一种新型的能够防止两块磁盘失败的技术

海量存储系统的建设是目前计算机系统最热门和发展最快的领域,存储系统的主要部分是在线存储系统。RAID(磁盘阵列)对于提升存储系统的效率、数据的高可靠性、防止数据破坏和业务停顿具有重大意义。目前实际应用中的RAID 1,RAID 0+1,RAID 4,RAID 5都只能防止单块磁盘的损坏,实际生产中已经出现了很多由于双盘损坏造成业务长时间停顿的事故。在介绍了通用的RAID级别的基础上,介绍了一种新型的对角线奇偶校验方法,结合水平奇偶校验,可以防止两块磁盘损坏。通过可靠的数学分析,可以看到该方法可以极大提高磁     

A reliable and energy-efficient storage system with erasure coding cache

In modern energy-saving replication storage systems, a primary group of disks is always powered up to serve incoming requests while other disks are often spun down to save energy during slack periods. However, since new writes cannot be immediately synchronized into all disks, system reliability is degraded. In this paper, we develop a high-reliability and energy-efficient replication storage system, named RERAID, based on RAID10. RERAID employs part of the free space in the primary disk group and uses erasure coding to construct a code cache at the front end to absorb new writes. Since code cache supports failure recovery of two or more disks by using erasure coding, RERAID guarantees a reliability comparable with that of the RAID10 storage system. In addition, we develop an algorithm, called erasure coding write (ECW), to buffer many small random writes into a few large writes, which are then written to the code cache in a parallel fashion sequentially to improve the write performance. Experimental results show that RERAID significantly improves write performance and saves more energy than existing solutions.     

MT2RAID:一种高可靠大规模磁盘阵列结构

传统的磁盘阵列一般采用集中式控制结构,其连接的底层磁盘数受系统总线的制约,容易出现性能瓶颈,且不能容两个以上磁盘出错。从模块化系统的组织方法出发,提出一种采用标准模块化存储单元组成的通过胖树结构互连的大规模磁盘阵列结构MT2RAID,分别就其各种数据分布的性能和可靠性进行了分析和讨论。原型系统测试结果表明,相比集中式磁盘阵列结构,MT2RAID也具有较高的性能。     

RAID 4SMR: RAID Array with Shingled Magnetic Recording Disk for Mass Storage Systems

One way to increase storage density is using a shingled magnetic recording (SMR) disk. We propose a novel use of SMR disks with RAID (redundant array of independent disks) arrays, specifically building upon and compared with a basic RAID 4 arrangement. The proposed scheme (called RAID 4SMR) has the potential to improve the performance of a traditional RAID 4 array with SMR disks. Our evaluation shows that compared with the standard RAID 4, when using update in-place in RAID arrays, RAID 4SMR with garbage collection not just can allow the adoption of SMR disks with a reduced performance penalty, but offers a performance improvement of up to 56%.