14017324
A checkpointing tool for Palm operating system
It is foreseeable that handheld devices will be involved in the arena of distributed computing in the near future. To provide a dependable computing environment, check-pointing and rollback recovery is a useful and important technique for fault-tolerant distributed computing systems. For the most popular platform among handhelds, Palm OS, its built-in HotSync tool can take a partial snapshot of a system state, but it synchronizes only the static data in the handheld with a PC. All dynamic data of applications are lost if a failure occurs and the Palm OS is reset. In order to accommodate mobile computing devices with checkpointing and rollback recovery capability, dynamic data such as global variables should be checkpointed to tolerate system reset/crash failure. Therefore, we developed a checkpointing tool, which provides a set of APIs to checkpoint Palm applications. Using the checkpointing tool, dynamic data in a Palm device can be saved and recovered from a system reset. We describe the tool and demonstrate its usefulness in four popular Palm applications.
17854992
Distributed Fault-Tolerant Ring Embedding and Reconfiguration in Hypercubes
To embed a ring in a hypercube is to find a Hamiltonian cycle through every node of the hypercube. It is obvious that no 2/sup n/-node Hamiltonian cycle exists in an n-dimensional faulty hypercube which has at least one faulty node. However, if a hypercube has faulty links only and the number of faulty links is at most n-2, at least one 2/sup n/-node Hamiltonian cycle can be found. In this paper, we propose a distributed ring-embedding algorithm that can find a Hamiltonian cycle in a fault-free or faulty n-dimensional hypercube (Q,), and the complexity is O(n) parallel steps. The algorithm is based on the recursion property of the hypercube and the free-link dimension concept. In some cases, even when the number of faulty links is larger than n-2, Hamiltonian cycles may still exist. We show that the largest possible number of faulty links that can be tolerated is 2/sup n-1/-1. The performance and the constraints of the fault-tolerant algorithm is also analyzed in detail in this paper. Furthermore, a dynamic reconfiguration algorithm for an embedded ring is proposed and discussed. Due to the distributed nature of the algorithms, they are useful for the simulation of ring-based multiprocessors on MIMD hypercube multiprocessors.
30164245
Reliable Multicast based on k-Connected Graph
26449771
Resolving error propagation in distributed systems
This paper investigates the problem of error propagation in distributed systems. To resolve this problem, a state preservation scheme is presented to save process states in main memory. Based on the state preservation, the processes suffering from error propagation can be recovered without involving stable storage. The recovery overhead is significantly reduced. In addition, a well-known single-source-all-destination graph algorithm is also utilized to find the optimal recovery points of the processes suffering from error propagation.
25953242
Restoration from Multiple Faults in WDM Networks without Wavelength Conversion
This paper addresses the problem of achieving full and fast restoration to tolerate as many faults as possible in wavelength-routed wavelength division multiplexing (WDM) networks with no wavelength conversion. We model the problem of finding the maximum number of faults tolerated as a constrained ring cover problem, which is a decomposition problem of exponential complexity. Three heuristic methods which guarantee that at least one fault can be tolerated are proposed. The Ear Decomposition (ED) method can always generate a decomposition to guarantee that only one fault can be tolerated. The Planar Decomposition (PD) method, which takes advantage of the bipartite graph model to generate a decomposition, can tolerate up to f faults, where f is the maximum cardinality between the two bipartite vertex sets. The Maximally Separated Rings (MSR) method uses the greedy method to find a decomposition to tolerate as many faults as possible. The marked-link (ML) method is also proposed to enhance the performance by marking some links, which are originally used for protection, available for normal transmissions. Finally, we also evaluate the number of faults tolerated and the blocking probabilities of these methods in three example networks.
11124619
Effort-index-based software reliability growth models and performance assessment
The authors show that the logistic testing effort function is practically acceptable/helpful for modeling the software reliability growth and providing a reasonable description of resource consumption. Therefore, in addition to the exponential shaped models, we integrate the logistic testing effort function into an S-shaped model for further analysis. The model is designated as the Yamada Delayed S-shaped model. A realistic failure data set is used in the experiments to demonstrate the estimation procedures and results. Furthermore, the analysis of the proposed model under an imperfect debugging environment is investigated. In fact, from these experimental results and discussions, it is apparent that the logistic testing-effort function is very suitable for making estimations of resource consumption during the software development/testing phase.
13132411
A New Probabilistic Induction Method
Knowledge acquisition by interviewing a domain expert is one of the most problematic aspects of the development of expert systems. As an alternative, methods for inducing concept descriptions from examples have proven useful in eliminating this bottleneck. In this paper, we propose a probabilistic induction method (PIM), which is an improvement of the Chan and Wong method, for detecting relevant patterns implicit in a given data set. PIM uses the technique of residual analysis and several heuristics to effectively detect complex relevant patterns and to avoid the problem of combinatorial explosion. A reasonable trade-off between the induction time and the classification ratio is achieved. Moreover, PIM quickly classifies unknown objects using classification rules converted from the positively relevant patterns detected. Three experiments are conducted to confirm the validity of PIM.
46555623
Design and evaluation of fault-tolerant interleaved memory systems
A highly reliable interleaved memory system for uniprocessor and multiprocessor computer architectures is presented. The memory system is divided into groups. Each group consists of several banks and furthermore, each bank has several memory units. Spare memory units as well as spare banks are incorporated in the system to enhance reliability. Reliability figures are derived to evaluate systems with various amounts of redundancy. The result shows that the system reliability can be significantly improved with little hardware overhead. User transparency in memory access is retained.<<ETX>>