基于COTS的容错服务器及其故障恢复技术

通过融合COTS技术和传统容错技术设计实现了一种高性能、高可靠的容错服务器，该服务器基于成熟的软硬件，开放性好，容错对用户透明，成本低，扩展能力强。该文详细介绍了服务器的体系结构、工作模型、容错机制及其前向故障恢复技术。     

网口容错在嵌入式设备中的设计与实现

针对嵌入式网络设备的服务可靠性问题,现有的网口容错主要采用双网卡冗余设计,研究针对单网卡多网口的情况,提出了一种网口容错方法,该方法能有效利用系统带宽资源。提出的网口容错方法包括一种网口状态检测机制和故障网口服务数据迁移方法,并设计了相应的功能模块。故障检测模块实现基于Loopback的检测方法,容错处理模块则实现在检测到故障后,可将故障网口的服务负载数据根据迁移策略迁移到其余正常网口。所提出的方法实现了对网口工作状态的快速检测和负载数据的有效容错。该方法具有应用无关性、资源占用率低的特点,通过测试验证了该方法的可行性。     

采用故障接管策略的容错MPI实现技术

面向集群系统的通信故障，研究了如何在消息传递层采用故障接管实现通信子系统的透明容错。并描述了基于高性能通信接口NICHAL的容错MPI(R-MPI)实现，测试数据表明该实现有效利用TRDMA特征实现容错通信协议。     

基于神经网络的非线性系统故障检测及容错控制方法

利用神经网络的非线性建模能力，提出了一种非线性系统的故障检测及容错控制方法。在本方法中，首先应用神经网络设计故障估计器，在线估计系统故障向量，实现故障检测；在此基础上，引入补偿控制器，消除故障对系统运行的影响，从而实现容错控制。同时基于Ｌｙａｐｕｎｏｖ方法进行了稳定性分析。     

风洞试验过程故障智能容错控制

本文以某些风洞为监测对象，着重介绍了风洞试验过程故障智能容错控制系统的基本配置，原理和方法，同时对诊断标准的确定，容错功能的实现等进行了分析和讨论。     

工业设备故障的计算机自动检测与容错控制

本文根据工业设备的故障特点，提出了利用计算机对设备故障进行自动检测和容错控制的设计方法。着重介绍了设备故障计算机自动检测、故障容错控制系统的基本结构及故障容错控制的实现方法等。该方法对延长设备的使用寿命、增强设备故障自治能力、提高设备运行的安全性和可靠性，具有工程应用价值。     

针对传感器故障的容错控制问题的数值解法

针对状态反馈闭环系统中的传感器故障容错控制问题，先基于稳定多项式分解导出该容错控制问题状态反馈闭环系统稳定的充分必要条件。在此基础上，基于相容非线性方程组数值解法，提出具有传感器故障容错控制的状态反馈律设计方法。还基于数值优化解方法，提出面向闭环系统极点配置的另一状态反馈容错控制律设计方法。计算机仿真算例表明此方法的有效性。     

容错控制系统综述

本文讨论了故障系统的容错控制设计问题.对各种故障系统的容错控制设计方法,从其原理、特征及应用等方面作了详细的综述,主要包括各种故障的监测与隔离方法和各种容错控制器的设计方法.最后对容错控制系统设计的发展趋势作了简要介绍.     

直流调速系统故障在线检测与容错控制

本文根据直流调速系统的故障特点，提出了利用微型计算机对其运行故障进行自动检测与容错控制的设计方法。着重对电源缺相、电机主轴承磨损故障的容错控制及其实现进行了分析和讨论。     

工业设备故障容错控制及其实现

本文根据工业设备的故障特点，提出了根据检测的故障信息，利用综合冗余和补偿技术对其故障进行容错控制的设计方法。文中着重介绍了工业设备故障容错控制系统的结构原理，并对其实现问题进行了分析和讨论，文末给出了一个工程实例。     

基于补偿服务链的Web服务容错机制研究与实现

针对网络故障以及Web服务节点暂时性失效,导致Web服务请求出错的问题,提出了一种Web服务容错机制.通过建立服务补偿机制和Web服务会话管理机制达到容错的目的.首先对Web服务的容错性问题进行了分析;接着详细论述了服务补偿机制和容错框架的设计与实现方案;最后通过在政务服务集成系统中的应用实例说明了该容错机制能够有效地增强Web服务请求调用的可靠性.     

基于RTLinux的容错硬实时性的研究与实现

容错已逐渐成为实时系统的一个重要特性,针对RTLinux的实时调度机制尚未考虑容错的需求,对RTLinux进行了容错硬实时性的改造.改造了基于主/副版本容错模型对任务模型,对先前提出的基于最坏响应时间的容错实时任务可调度性分析,通过将改进的最佳容错分配因子搜索算法(improved fault-tolerant priority configuration search algorithm,IFPCS)运用到实时调度算法中,提高了RTLinux的容错实时性能,并给出了容错实时程序的设计框架.     

计算机系统容错技术研究

针对计算机系统中软、硬件可靠性问题的不同特点,讨论容错技术的最新发展现状,分析计算机系统中的各种容错方法,包括传统的冗余设计、错误回卷恢复机制以及当前研究较多的一般化容错设计方法等,研究目前已有的一些容错方法在反应延迟、容错成本、精确量化、异构同步、可靠性建模等方面存在的缺陷以及待解决关键问题,并对如何进一步更好地完善和使用这些容错方法进行总结。     

Fault tolerant processes

A process is said to be fault tolerant if the system provides proper service despite the failure of the process. For supporting fault-tolerant processes, measures have to be provided to recover messages lost due to the failure. One approach for recovering messages is to use message-logging techniques. In this paper, we present a model for message-logging based schemes to support fault-tolerant processes and develop conditions for proper message recovery in asynchronous systems. We show that requiring messages to be recovered in the same order as they were received before failure is a stricter requirement than necessary. We then propose a distributed scheme to support fault-tolerant processes that can also handle multiple process failures.Pankaj Jalote received the Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology, Kanpur, India, in 1980, the M.S. degree in computer science from Pennsylvania State University, University Park, in 1982, and the Ph.D. degree in computer science from the University of Illinois at Urbana-Champaign in 1985. From August 1985 to July 1989 he was an Assistant Professor in the Department of Computer Science at the University of Maryland, College Park. Currently he is an Assistant Professor in the Department of Computer Science and Engineering at IIT Kanpur, India. His research interests include fault-tolerant computing, distributed systems, and software engineering.This work was supported in parts by the NSF grant DCI-8610337     

Adding fault-tolerant transaction processing to LINDA

To simplify the difficult task of writing fault-tolerant parallel software, we implemented extensions to the basic functionality of the LINDA or tuple-space programming model. Our approach implements a mechanism of transaction processing to ensure that tuples are properly handled in the event of a node or communications failure. If a process retrieving a tuple fails to complete processing or a tuple posting or retrieval message is lost, the system is automatically rolled back to a previous stable state. Processing failures and lost messages are detected by time-out alarms. Roll-back is accomplished by reposting pertinent tuples. Intermediate tuples produced during partial processing are not committed or made available until a process completes. In the absence of faults, system overhead is low. The fault-tolerance mechanism is implemented at the system level and requires little programmer effort or expertise. Two implementations of the model are discussed, one using a UNIX network of workstations and one using a Transputer network. Data measuring model overhead and some aspects of system performance in the presence of faults is presented for an example system.     

Fault-Tolerant Gait Planning for a Hexapod Robot Walking over Rough Terrain

Multi-legged robots need fault-tolerant gaits if one of attached legs suffers from a failure and cannot have normal operation. Moreover, when the robots with a failed leg are walking over rough terrain, fault-tolerance should be combined with adaptive gait planning for successful locomotion. In this paper, a strategy of fault-tolerant gaits is proposed which enables a hexapod robot with a locked joint failure to traverse two-dimensional rough terrain. This strategy applies a Follow-The-Leader (FTL) gait in post-failure walking, having the advantages of both fault-tolerance and terrain adaptability. The proposed FTL gait can produce the maximum stride length for a given foot position of a failed leg and better ditch-crossing ability than the previous fault-tolerant gaits. The applicability of the proposed FTL gait is verified using computer graphics simulations.     

利用遗传算法改善前馈神经网络容错性

针对前馈神经网络的断路故障,将网络容错性的改善转化为一个最小优化问题,并通过遗传算法进化求解来获取容错性好、泛化能力强的网络,该方法不需给网络增加额外冗余,也不需修改网络训练算法,较好地保持了网络结构、训练算法与容错处理的独立性,实验表明,该方法在两个基准测试问题上均取了很好的效果。     

Requirements for a COTS software component: A case study

The goal of the GUARDS project is to design and develop a generic fault-tolerant computer architecture that can be built from predefined standardised components. The architecture favours the use of commercial off-the-shelf (COTS) hardware and software components. However, the assessment and selection of COTS components is a non-trivial task as it requires balancing a myriad of requirements from end-users and the preliminary architecture design. In this paper, we present the requirements and assessment criteria for a specific COTS software component, the operating system kernel. As an interface specification constitutes a major compatibility criterion for the selection of COTS components in GUARDS, a particular emphasis is placed on operating system conformance to the POSIX 1003.1 standard. We discuss the general lessons learned from the assessment process and raise a number of questions relevant to the assessment of any COTS software component.     

基于GCC的容错编译器的研究与实现

在COTS微处理器上实现面向硬件故障的软件容错技术,与硬件容错技术相比,其性能、成本、功耗和灵活性上都拥有巨大的优势。其中容错编译技术通过在编译的时候自动地插入指令实现容错,实现简单、高效,不需要重写源代码,减轻了程序员的负担,有利于利用已有的大量程序,是软件容错研究中较为活跃的分支。本文以GNU开源编译器GCC为平台,结合现有容错编译算法,讨论一款初步具有容错编译能力的编译器的设计与实现。     

三模容错多处理器动态实时调度算法

实时系统现在面临着越来越迫切的容错要求。目前流行的主副备份方式对于任务集有着特殊要求,要求时间限能够允许主副备份串行地执行,并且系统需要提供相应的硬件来检测处理器错误,因此限制了容错的应用范围。本文提出基于三模冗余比较的实时容错算法,采用了副本重载技术和主副本串并行混合调度策略。分析和实验结果表明,该算法具
有更好的适应性。