磁盘阵列性能测试工具研究

目前国内外有许多优秀的性能评测基准如TPC、SPC、IOMeter、IOZONE等,但它们在应用环境和功能上存在一些限制。为了解决这个问题,设计并实现了一个基于Linux分布式系统的磁盘阵列性能测试工具DAMeter,并与业内广泛使用的Windows下磁盘阵列性能测试基准IOMeter进行对比实验,证明了DAMeter工具测试结果的准确性和可靠性。并介绍了如何使用DAMeter产生不同负载进行磁盘阵列性能测试。     

一种SCSI目标器设计与评估

SCSI目标器是磁盘阵列控制器软件中的关键组成部分之一;设计并实现了一种SCSI目标器,详细描述了SCSI目标器的功能及其内部体系结构,阐述了目标器对读写请求的不同处理流程;该SCSI目标器是可配置的,它既能够辅助磁盘阵列控制器软件系统开发,也能够胜任磁盘阵列控制器SCSI目标器的功能;为了验证该SCSI目标器的性能,采用相关评测工具对其有负载和无负载两种情况的读写性能进行了评测,测试结果表明该SCSI目标器的实际性能达到了预期的设计目标。     

基于Web应用系统的评测方法和技术

在现有Web服务器的评测方法和技术基础上对Web应用系统进行性能测试的一些研究，主要定义了一套测试基于Web的应用系统的术语和性能指标集，并提出了性能测试的总体方案，对生成工作负载的相关问题也作了简要的说明。     

计算机网络系统的性能评测

计算机网络系统的性能评测是网络规划和网络管理的核心内容.基于对计算机网络的基本结构和计算机网络硬件设备的功能分析,从复杂性和成本的角度来说,计算机网络性能评测的方法分为四种,即经验法则、分析方法、测量方法以及仿真方法.同时,着眼于评测计算机网络系统的性能指标,对可度量的性能指标与不可度量的性能指标进行了详细的讨论.并分析了影响计算机网络性能的因素.最后,基于SNMP协议对可度量的性能指标的获取进行了实现.     

Linux操作系统性能评测与测试指标浅析

操作系统性能是对其进行综合评测的重要指标之一。本文以多个主流Linux服务器操作系统的性能测试实践为基础,概括了对Linux操作系统进行性能测试和对比评测的测试策略和性能测试工具的选择原则,并对主要性能测试工具和关键性能指标进行了说明。     

关系数据库缓冲区置换策略的性能评测

缓冲区是计算机领域一个非常重要的研究主题。现在存在很多缓冲区置换策略,广泛地用于操作系统、文件系统、数据库以及存储系统中。提出了一种性能评测方法来评测关系数据库的缓冲区置换策略。这种方法采用直接测试方式,使用五个性能指标,包括新提出的指标以及由于模拟方法的局限性在以前的研究中很少使用的性能指标,同时利用显著性测试并提出一种联合使用多个显著性测试的方法进行置换策略之间的比较,设计和使用多种工作负载在单用户和多用户情况下有效地评测各种策略。使用这种评测方法,在一个真实的关系数据库环境中,对十三种典型的缓冲区置换策略的性能进行了详细、全面的实验研究,从中可以获得一些有用的结论。     

光纤通道磁盘阵列中目标器设计与实现

磁盘阵列已成为构建大型存储系统的关键基础设备,目标器为主机提供存储设备访问接口.本文结合RAID原型系统, 分析了光纤通道磁盘阵列中目标器模块的功能及其内部体系结构,阐述了目标器对读写请求的不同处理流程,最后采用相关评测工具对光纤通道目标器模块以及RAID系统进行了性能评测,测试结果表明光纤通道目标器模块具有出色的性能,最高数据传输率可达187Mbye/s.     

基于龙芯2F处理器的硬件验证平台的设计与实现

针对高性能处理器龙芯2F的逻辑验证和性能测试,本文设计和实现了一套硬件验证平台环境,既能验证处理器流片前的逻辑功能,也能测试处理器流片后的性能指标。实验结果表明,本文设计的硬件验证平台能够有效验证龙芯2F处理器的各项功能和性能指标。     

面向大数据存储的主动与被动相结合的性能评测方法体系结构与实现

随着数据量的日益增加,大数据存储在整个大数据应用框架体系中居于重要地位。对大数据存储系统进行性能评测可以指导大数据应用开发人员分析性能瓶颈,进行大数据系统的性能优化。在以往的工作中,通常使用基准测试的方式来对不同大数据框架进行性能评测,或者采用插桩并分析轨迹文件的方式对分布式文件系统进行性能分析。这2种方法采用的分析角度不同,并没有形成合理的评测体系来评价大数据分布式存储系统。本文提出主动与被动相结合的大数据存储系统性能评测方法体系结构及其具体实现。在主动性能评测方法方面,提供了6个领域,超过20个应用的基准测试程序,对大数据存储系统主动发起性能测试,分析大数据存储系统的基准性能指标;在被动性能评测方法方面,提供了对低效任务、低效算子、低效函数的分析及定位方法,通过分析运行在大数据存储系统之上的大数据应用,分析大数据应用程序低效的原因。通过实验表明,该大数据性能评测方法体系结构能够全面地对大数据存储系统进行性能评测。     

Infiniband通道磁盘阵列中目标器的设计与实现

磁盘阵列对海量信息的存储与处理,数据的可用性和性能具有重要的意义,目标器为主机提供设备映射和设备访问接口.设计和实现了SRP协议的目标器,通过主机HCA卡GUID标识来实现存储系统逻辑资源的授权访问,对目标器对读写请求的处理流程进行了介绍,采用评测工具对SRP协议目标器模块进行了性能测试,测试结果表明SRP协议目标器具有较好的性能,最高数据传输率达到IB理论带宽的极限.     

Issues and challenges in the performance analysis of real disk arrays

The performance modeling and analysis of disk arrays is challenging due to the presence of multiple disks, large array caches, and sophisticated array controllers. Moreover, storage manufacturers may not reveal the internal algorithms implemented in their devices, so real disk arrays are effectively black-boxes. We use standard performance techniques to develop an integrated performance model that incorporates some of the complexities of real disk arrays. We show how measurement data and baseline performance models can be used to extract information about the various features implemented in a disk array. In this process, we identify areas for future research in the performance analysis of real disk arrays.     

Efficient striping techniques for variable bit rate continuous media file servers

The performance of striped disk arrays is governed by two parameters: the stripe unit size and the degree of striping. In this paper, we describe techniques for determining the stripe unit size and degree of striping for disk arrays storing variable bit rate continuous media data. We present an analytical model to determine the optimal stripe unit size in redundant and non-redundant disk arrays. We then use the model to study the effect of various system parameters on the optimal stripe unit size. To determine the degree of striping, we first demonstrate that striping a continuous media stream across all disks in the array causes the number of clients supported to increase sub-linearly with increase in the number of disks. To overcome this limitation, we propose a technique that partitions a disk array and stripes each media stream across a single partition. We then propose an analytical model to determine the optimal partition size and maximize the number of clients supported by the array.     

高端磁盘阵列可靠性测试建模方法研究

阐述了衡量高端磁盘阵列可靠性的重要指标MTTDL,通过分析两种造成磁盘错误的原因,建模计算了各种RAID级别的MTTDL,设计了磁盘读出错率的测试方案,实现了基于分布式的磁盘读出错率测试程序。     

Performance of RAID5 disk arrays with read and write caching

In this paper, we develop analytical models and evaluate the performance of RAID5 disk arrays in normal mode (all disks operational), in degraded mode (one disk broken, rebuild not started) and in rebuild mode (one disk broken, rebuild started but not finished). Models for estimating rebuild time under the assumption that user requests get priority over rebuild activity have also been developed. Separate models were developed for cached and uncached disk controllers. Particular emphasis is on the performance of cached arrays, where the caches are built of Non-Volatile memory and support write caching in addition to read caching. Using these models, we evaluate the performance of arrayed and unarrayed disk subsystems when driven by a database workload such as those seen on systems running any of several popular database managers. In particular, we assume single-block accesses, flat device skew and little seek affinity.With the above assumptions, we find six significant results. First, in normal mode, we find there is no difference in performance between subsystems built out of either small arrays or large arrays as long as the total number of disks used is the same. Second, we find that if our goal is to minimize the average response time of a subsystem in degraded and rebuild modes, it is better to use small arrays rather than large arrays in the subsystem. Third, we find the counter-intuitive result that if our goal is to minimize the average response time of requests to any one array in the subsystem, it is better to use large arrays than small arrays in the subsystem. We call this the best worst-case phenomenon.Fourth, we find that when no caching is used in the disk controller, subsystems built out of arrays have a normal mode performance that is significantly worse than an equivalent unarrayed subsystem built of the same drives. For the specific drive, controller, workload and system parameters we used for our calculations, we find that, without a cache in the controller and operating at typical I/O rates, the normal mode response time of a subsystem built out of arrays is 50% higher than that of an unarrayed subsystem. In rebuild mode, we find that a subsystem built out of arrays can have anywhere from 100% to 200% higher average response time than an equivalent unarrayed subsystem.Out fifth result is that, with cached controllers, the performance differences between arrayed and equivalent unarrayed subsystems shrink considerably. We find that the normal mode response time in a subsystem built out of arrays is only 4.1% higher than that of an equivalent unarrayed system. In degraded (rebuild) mode, a subsystem built out of small arrays has a response time 11% (13%) higher and a subsystem built out of large arrays has a response time 15% (19%) higher than an unarrayed subsystem.Our sixth and last result is that cached arrays have significantly better response times and throughputs than equivalent uncached arrays. For one workload, a cached array with good hit ratios had 5 times the throughout and 10 to 40 times lower response times than the equivalent uncached array. With poor hit ratios, the cached array is still a factor of 2 better in throughput and a factor of 4 to 10 better in response time for this same workload.We conclude that 3 design decisions are important when designing disk subsystems built out of RAID level 5 arrays. First, it is important that disk subsystems built out of arrays have disk controllers with caches, in particular Non-Volatile caches that cache writes in addition to reads. Second, if one were trying to minimize the worst response time seen by any user, one would choose disk array subsystems built out of large RAID level 5 arrays because of the best worst-case phenomenon. Third, if average subsystem response time is the most important design metric, the subsystem should be built out of small RAID level 5 arrays.     

Disk arrays: high-performance, high-reliability storage subsystems

As the performance of other system components continues to improve rapidly, storage subsystem performance becomes increasingly important. Storage subsystem performance and reliability can be enhanced by logically grouping multiple disk drives into disk arrays. Array data organizations are defined by their data distribution schemes and redundancy mechanisms. The various combinations of these two components make disk arrays suitable for a wide range of environments. Many array implementation decisions also result in trade-offs between performance and reliability. Disk arrays are thus an essential tool for satisfying storage performance and reliability requirements, while proper selection of a data organization can tailor an array to a particular environment     

小型高可靠磁盘阵列技术若干问题的研究

高可靠磁盘阵列是采用相对廉价的、小容量的高性能磁盘驱动器为单元，通过一定的方式，组成磁盘阵列以提高磁盘容量，提高数据的传输率，目前这一技术已经在国内外引起计算机界的广泛关注。本文将对廉价磁盘冗余阵列体系结构、磁盘阵列控制器及实现过程中理论上和工程上需要解决的若干问题进行一些探讨和研究。     

Technology Trends and Disk Array Performance

The original design of disk arrays was motivated primarily by the desire for greater fault tolerance and higher data transfer rates than those achievable with a single disk. However, disk technology has continued to evolve, driven largely by the needs of the commodity personal computer market, rather than those of the “niche markets” of parallel and fault-tolerant computing. Using a combination of analytic modeling and simulation, we consider four disk array designs and extrapolate the behavior of these designs as a function of predicted changes in disk technology. The results of this analysis suggest that changes in disk technology may lessen, though not eliminate, the current performance advantages of disk arrays and may shift current design points.     

容许两个盘故障的磁盘阵列数据布局与图分解的条件和存在性研究

从一个新的途径讨论容许两个盘故障的磁盘阵列数据布局：把由数据单元和通过“异或”运算得到的校验单元组成的校验组用一个图表示，把校验组容许两个盘故障的阵列布局归结为校验组的单元集合的划分，进而转化为校验组的图的顶点和边组成集合的满足一定条件的分解．证明了校验组容许两个盘故障的单元集合划分的充分必要条件及存在性；讨论了优化阵列布局方案性能的条件；给出了阵列布局的步骤．从而为设计具有最优性能的容许两个盘故障的磁盘阵列数据布局方案提供了有效的途径．     

Coding techniques for handling failures in large disk arrays

A crucial issue in the design of very large disk arrays is the protection of data against catastrophic disk failures. Although today single disks are highly reliable, when a disk array consists of 100 or 1000 disks, the probability that at least one disk will fail within a day or a week is high. In this paper we address the problem of designing erasure-correcting binary linear codes that protect against the loss of data caused by disk failures in large disk arrays. We describe how such codes can be used to encode data in disk arrays, and give a simple method for data reconstruction. We discuss important reliability and performance constraints of these codes, and show how these constraints relate to properties of the parity check matrices of the codes. In so doing, we transform code design problems into combinatorial problems. Using this combinatorial framework, we present codes and prove they are optimal with respect to various reliability and performance constraints.This paper is a revised and expanded version of material that appeared at the Third International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS III), Boston, MA, March 1989. The work here was supported in part by the National Science Foundation under Grant Numbers MIP-8715235 and CCR-8411954, as well as an AT&T Bell Labs GRPW grant, a Siemens Corporation grant, and an IBM graduate fellowship.     

Stripped mirroring RAID architecture

Redundant arrays of independent disks (RAID) provide an efficient stable storage system for parallel access and fault tolerance. The most common fault tolerant RAID architecture is RAID-1 or RAID-5. The disadvantage of RAID-1 lies in excessive redundancy, while the write performance of RAID-5 is only 1/4 of that of RAID-0. In this paper, we propose a high performance and highly reliable disk array architecture, called stripped mirroring disk array (SMDA). It is a new solution to the small-write problem for disk array. SMDA stores the original data in two ways, one on a single disk and the other on a plurality of disks in RAID-0 by stripping. The reliability of the system is as good as RAID-1, but with a high throughput approaching that of RAID-0. Because SMDA omits the parity generation procedure when writing new data, it avoids the write performance loss often experienced in RAID-5.