AutoProc: An automatic proactive replication scheme for P2P storage

Due to the prevalence of peer departures, P2P storage systems need to constantly generate replicas for high durability. However, few existing systems are able to select the right replication rate that balances replication cost and durability, e.g., minimizing replication cost without threatening the durability target. In this paper, we propose a method called AutoProc to automate the replication process in P2P storage systems. AutoProc employs two key techniques to enable cost-effective replication: correct...     

Super connectivity of Kronecker products of graphs

Let G₁ and G₂ be two connected graphs. The Kronecker product G₁×G₂ has vertex set V(G₁×G₂)=V(G₁)×V(G₂) and the edge set . In this paper, we show that if G is a bipartite graph with κ(G)=δ(G), then G×Kn(n?3) is super-κ.     

结构化P2P系统中副本一致性管理的一种新算法

结构化P2P系统通常使用数据复制来提高数据可用性,但P2P环境中的节点搅动、多节点并发更新以及恶意节点的存在也为副本的一致性管理带来了新的挑战.基于协商的算法要求节点间以全交换的方式通讯,在P2P环境中其可伸缩性不够理想.本文针对结构化P2P系统提出一种基于Quorum的副本管理算法:使用混合失效模型降低容错开销,利用DHT服务处理节点搅动,将数据存储与其元信息管理分离,使数据可靠性和数据可用性得以独立调整.模拟实验表明该算法可以明显改善系统的可伸缩性,减少系统的容错开销.     

指令级的变量容错恢复

提出一种抵抗瞬时故障的自动编译容错恢复方法,用源码中的变量信息在指令级别进行冗余错误流裁剪,在LCC上加以实现,并获得良好的容错性能。实验结果表明,该方法仅增加0.043倍的时间损耗及0.69倍的空间损耗,在时空损耗上优于现有的其他方法。     

可靠的网格作业调度机制

针对网格环境的动态性特征,提出了一种可靠的网格作业调度机制(DGJS)。按照作业完成时间期限,DGJS将作业分为：高QoS级、低QoS级和无QoS级,不同QoS级作业有不同的调度优先权;基于资源可用性预测,DGJS采用基于可靠性代价的作业调度策略,将作业尽可能调度到可靠性高的资源节点;另外,DGJS对不同QoS级作业采用不同的容错策略,在保证故障容错的同时,节省网格资源。实验表明：在动态的网格环境下,较之传统的网格作业调度算法,DGJS提高了作业成功率,减少了作业完成时间。     

Redirection based recovery for MPLS network systems

To provide a reliable backbone network, fault tolerance should be considered in the network design. For a multiprotocol label switching (MPLS) based backbone network, the fault-tolerant issue focuses on how to protect the traffic of a label switched paths (LSP) against node and link failures. In IETF, two well-known recovery mechanisms (protection switching and rerouting) have been proposed. To further enhance the fault-tolerant performance of the two recovery mechanisms, the proposed approach utilizes the failure-free LSPs to transmit the traffic of the failed LSP (the affected traffic). To avoid affecting the original traffic of each failure-free LSP, the proposed approach applies the solution of the minimum cost flow to determine the amount of affected traffic to be transmitted by each failure-free LSP. For transmitting the affected traffic along a failure-free working LSP, IP tunneling technique is used. We also propose a permission token scheme to solve the packet disorder problem. Finally, simulation experiments are performed to show the effectiveness of the proposed approach.     

胖树中的分布式动态容错路由

面向云计算的超大规模互连网络增加了对网络容错的要求,容错已成为互连网络的重要问题.为了保证网络的高可用性和高性能,文中基于胖树网络拓扑提出了一种分布式的动态容错路由方法.该方法通过引入一套链路失效消息传播机制和一套基于链路失效信息的动态容错路由算法来实现胖树网络的分布式动态容错.相比已有方法,该方法不增加网络硬件和路由路径长度,并且具有高执行效率和高性能.实验结果表明,在m端口交换机构成的胖树中,该方法可以容忍任意m/2-1条失效链路并以高概率容忍更多条失效链路的组合,同时保持网络的高性能.     

Biswapped网络(BSN)的拓扑性质研究:点对称性和极大容错性

Biswapped网络(BSN)是一类两层结构的互连网络,它以任意图为模块且模块间采用一种完全两部图方式互连.BSN的互连形式与OTIS网络(即Swapped网络)类似但互连规则更一致,使得BSN展现出更好的性能.文中主要研究BSN的点传递性和容错性能.首先证明BSN能继承因子网络的点传递性质,为BSN上的分析和算法简单性找到理论依据.其次,通过直接构造网络中两点间最大数目的点不相交路径证明以任意连通图为因子网络的BSN是一致极大容错的.这些结果表明BSN既能继承因子网络的理想性能还展现某些好的新特性.最后,通过与OTIS网络、卡式积网络等层次类网络比较表明,BSN提供了一种构建可扩展性、模块化、容错性的大规模并行计算机系统的潜在有竞争力的体系结构形式.