Software Implemented Fault Tolerance in Multicomputers

本提案的主要目标是开发一种提高并行计算机可靠性的综合方法。对于本地（节点）级硬件故障的检测和诊断，该方法将结合离线内置自检、在线并发检查以及实现基于路径和算法的检查的软件技术。本建议的目的是开发一种系统的方法，用于在应用程序的实现中生成和放置检查。为了使验证过程和检查在程序中的位置自动化，将开发一种交互式工具VERIFY。为了评估这些技术提供的覆盖因子，将创建一个软件故障注入工具。将开发高效快速的重构算法，以避免单个和多个故障节点和链路。将创建一个用户透明的软件层来实现所提出的算法。这将在现有的系统软件之上编写，这些软件驻留在并行计算系统的每个节点上。软件面向对象故障注入工具（SOFIT）将被移植到nCUBE和Tandem SeverNet上。在执行程序时，如果SOFIT向nCUBE和SeverNet的节点和链路注入单个或多个故障，将估计恢复时间开销。将进行可靠性评估研究。本研究的目的是表明，这种集成方法可以成功地用于提高nCUBE和SeverNet的可靠性。

The main objective of this proposal is to develop an integrated approach for increasing the dependability of parallel computers. For detection and diagnosis of hardware faults at the local (node) level, this approach will combine off-line built-in self testing, on-line concurrent checking, and software techniques implementing path and algorithmic-based checks. The aim of this proposal is to develop a systematic method for generating and placing checks into the implementation of an application. For automating the verification process and placement of checks in programs, an interactive tool, VERIFY, will be developed. For estimating the coverage factor provided by these techniques, a software fault-injection tool will be created. Efficient and fast reconfiguration algorithms will be developed for avoiding single and multiple faulty nodes and links. A user transparent software layer will be created for implementing the proposed algorithms. This will be written on top of the existing system software that residents in every node of parallel computing systems. The Software Object-Oriented Fault-Injection Tool (SOFIT) will be ported on the nCUBE and Tandem SeverNet. The recovery time overhead will be estimated in the presence of single and multiple faults injected by SOFIT into the nodes and links of the nCUBE and SeverNet when programs are being executed. A dependability evaluation study will be performed. The objective of this research is to show that this integrated approach can be used successfully for improving the reliability of the nCUBE and SeverNet by an order of magnitude.