Fault-tolerant Solution Research Articles

Fault Detection and Recovery in Wireless Sensor Network Using Clustering

Some WSN by a lot of immobile node and with the limited energy and without further charge of energy. Whereas extension of many sensor nodes and their operation. Hence it is normal.unactive nodes miss their communication in network, hence split the network. For avoidance split of network, we proposed a fault recovery corrupted node and Self Healing is necessary. In this Thesis, we design techniques to maintain the cluster structure in the event of failures caused by energy-drained nodes. Initially, node with the maximum residual energy in a cluster becomes cluster heed and node with the second maximum residual energy becomes secondary cluster heed. Later on, selection of cluster heed and secondary cluster heed will be based on available residual energy. We use Matlab software as simulation platform quantities. like, energy consumption at cluster and number of clusters is computed in evaluation of proposed algorithm. Eventually we evaluated and compare this proposed method against previous method and we demonstrate our model is better optimization than other method such as Venkataraman, in energy consumption rate. Recent advances in MEMS (Micro-electro-mechanical systems) and wireless network technology have made the development of small, inexpensive, low power distributed devices, which are capable of local processing and wireless communication, a reality. Such devices are called sensor nodes. Sensors provide an easy solution to those applications that are based in the inhospitable and low maintenance areas where conventional approaches prove to be impossible and very costly. Sensors are generally equipped with limited data processing and communication capabilities and are usually deployed in an ad-hoc manner to in an area of interest to monitor events and gather data about the environment. Examples include environmental monitoring- which involves monitoring air soil and water, condition based maintenance, habitat monitoring, seismic detection, military surveillance, inventory tracking, smart spaces etc. Sensor nodes are typically disposable and expected to last until their energy drains. Therefore, it is vital to manage energy wisely in order to extend the life of the sensors for the duration of a particular task. (1-6). Failures in sensor networks due to energy depletion are continuous and may increase. This often results in scenarios where a certain part of the network become energy constrained and stop operating after sometime. Sensor nodes failure may cause connectivity loss and in some cases network partitioning. In clustered networks, it creates holes in the network topology and disconnects the clusters, thereby causing data loss and connectivity loss (10). Good numbers of fault tolerance solutions are available but they are limited at different levels. Existing approaches are based on hardware faults and consider hardware components malfunctioning only. Some assume that system software's are already fault tolerant as in (7, 8). Some are solely focused on fault detection and do not provide any recovery

Simulation-based analysis of middleware service impact on system reliability: Experiment on Java application server

Being a popular runtime infrastructure in the era of Internet, middleware provides more and more services to support the development, deployment and management of distributed systems. At the same time, the reliability of middleware services has a significant impact on the overall reliability of the system. Different services have different impacts and different service fault-tolerance solutions have different costs and risks. Therefore, the identification of the services that greatly affect the whole system reliability is the major obstacle to achieving reliable middleware-based systems. In this paper, we present an analytical framework to automatically reason and quantify such impacts when deploying the target system. In this framework, faults are represented by exceptions in modern programming languages; service failures are simulated by software fault injection; reliability impacts are measured by scenarios. This framework is demonstrated on multiple JEE application servers, including JBoss, JonAS and PKUAS. The experiments on two JEE blueprint applications, namely JPS and ECperf, show the feasibility, the applicability and the usability of this framework.

Spectroscopic ellipsometric properties and resistance switching behavior in Six(ZrO2)100x films

We prepare Six(ZrO2)100?x composite films using the co-sputtering method. The chemical structures of the films which are prepared under different conditions are analyzed with X-ray photoemission spectroscopy. Thermal treatment influences on optical property and resistance switching characteristics of these composite films are investigated by spectroscopic ellipsometry and semiconductor parameter analyzer, respectively. With the proper Si-doped Six(ZrO2)100?x interlayer, the Al/ Six(ZrO2)100?x/Al device cell samples present very reliable and reproducible switching behaviors. It provides a feasible solution for easy multilevel storage and better fault tolerance in nonvolatile memory application.

Designing an effective P2P system for a VoD system to exploit the multicast communication

A distributed video-on-demand system (DVoD) with multiple server-nodes is a cost-effective and fault-tolerant solution for a high scalable enterprise video-on-demand (VoD) system. However, such a server-oriented design is highly vulnerable to workload variations given that the service capacity is limited. Peer-to-Peer (P2P) has been introduced as an architectural solution with self-growing capacity. However, the characteristics of a pure P2P system such as the peer transient nature and high network overhead make this kind of architecture unsuitable for a fully interactive VoD system. In this paper, we propose a new efficient integrated VoD architecture, called D P n 2 P m , that combines DVoD with a P2P system and multicast communications. The DVoD’s server-nodes provide a minimum required quality of service (QoS) and the P2P system is able to offer the mechanism to increase the system service capacity according to client demands. Multicast communication, wherever it is possible, is effectively exploited by our P2P system. In our design, each client is able to send video information to a set of m clients using only one multicast channel. Furthermore, the collaboration mechanism is able to coordinate a set of clients to create one collaboration group to replace the server, providing an extensive, efficient and low network-overhead collaboration mechanism from n -peers to m -peers. Regardless of the video the client is watching, our P2P scheme allows every active client to collaborate with the server. The P2P scheme is complemented with recovery mechanisms that are able to replace the failed client before affecting the QoS, offering continuous playback. The proposed approach has been broadly evaluated, firstly using a mathematical model to derive the theoretical performance and secondly using a simulation environment to analyze the system’s dynamic behavior, the VCR interaction impact and the client failures. Comparing D P n 2 P m with other DVoD architectures and the most relevant P2P delivery policies, we show that our design is an improvement on previous solutions, providing a higher scalability.

Self-Adapting Event Configuration in Ubiquitous Wireless Sensor Networks

Wireless Sensor Networks are the key-enabler for low cost ubiquitous applications in the area of homeland security, health-care, and environmental monitoring. A necessary prerequisite is reliable and efficient event detection in spite of sudden failures and environmental changes. Due to the fact that the sensors need to be low cost, they have only scarce resources leading to a certain level of failures of sensor nodes or sensing devices attached to the nodes. Available fault tolerant solutions are mainly customized approaches that revealed several shortcomings, particularly in adaptability and energy efficiency. The authors present a complete event detection concept including all necessary steps from formal event definition to autonomous device configuration. It features an event definition language that allows defining complex events as well as enhance the reliability by tailor-made voting schemes and application constraints. Based on that, this paper introduces a novel approach for self-adapting on-node and in-network processing, called Event Decision Tree (EDT). EDT autonomously adapts to available resources and environmental conditions, even though it requires to (re-)organize collaboration between neighboring nodes for evaluation. The authors’ approach achieves fine-grained event-related fault tolerance with configurable adaptation rate while enhancing maintainability and energy efficiency.

Networking in E-textiles

The abundance of fabrics in our life offers immense possibilities for ubiquitous electronic integration. Electronic textiles (e-textiles) represent the merging of fabric and electronic technologies to be used in wearable and large-scale applications. The communication requirements of the computing elements of these systems will be presented along with a fault tolerant solution. The operation of the communication scheme will be studied analytically and compared to simulation results. The graceful deterioration of the performance with increasing faults will also be reported. Multiple e-textile application examples utilizing the networking scheme will be presented.

Robust Multiple-Phase Switched-Capacitor DC–DC Power Converter With Digital Interleaving Regulation Scheme

An integrated switched-capacitor (SC) DC-DC converter with a digital interleaving regulation scheme is presented. By interleaving the newly-structured charge pump (CP) sub-cells in multiple phases, the input current ripple and output voltage ripple of the converter are reduced significantly. The converter exhibits excellent robustness, even when one CP sub-cell fails to operate due to unexpected device failure. A fully digital controller is employed with hysteretic control, featuring deadbeat stability and fast transient response. With a 1.5-V input power supply, the SC power converter precisely provides an adaptable regulated power output from 1.6 to 2.7 V. A maximum output ripple of plusmn20 mV is observed at the full load of 540 mW. The load transient response is around 1.8 mus, when the load current switches from half to full load (from 100 to 200 mA). The design provides a fast-response, low-noise, and fault-tolerant solution to new-generation on-chip power supplies.

A Novel Approach for Fault Tolerance in Mobile IP based Wireless Networks

Next generation wireless networks are envisioned to have an IP based infrastructure with the support of heterogeneous access technologies. One of the research challenges for next generation all IP based wireless networks is the design of intelligent fault tolerant technique to provide interruptionless service to mobile users. Mobile IP supports wireless users with continuous network connection while changing location. This is achieved by allocating number of mobility agents in the architecture of a wireless system. If failure occurs in a mobility agent, the users located in the coverage area of faulty agent will lose their network connection. In order to provide mobile users with satisfactory quality of service and fault tolerant service it is required to cope with failure of mobility agents. In this paper, a new fault tolerant technique is proposed which provides an efficient fault tolerant solution for Mobile IP based wireless networks.

A solution for fault tolerance in replicated database systems

A distributed database system is subject to site failure and link failure. This paper presents a reactive system approach to achieving fault tolerance in such a system. The reactive system concepts are an attractive paradigm for system design, development and maintenance because it separates policies from mechanisms. In the paper we give a solution using different reactive modules to implement the fault tolerant policies and the failure detection mechanisms. The solution shows that they can be separated without impact on each other; thus the system can adapt to constant changes in environments and user requirements.

Fault-Tolerant Reconfigurable Ethernet-Based Ip Network Proxy

Using commonly available hardware and software, we present a proxy scheme for IP over Ethernet networks that provides a fault-tolerant solution without the need for modification of existing networking equipment. This type of fault-tolerant reconfigurable Ethernet-based proxy (FREP ) is transparent to current applications and provides full redundancy with minimal packet loss and fast reconfiguration times. A prototype implementation yielded a reconfiguration time of 1.55 sec. Used in conjunction with optimized dynamic routing protocols, it yielded an average recovery time of three seconds. The proposed proxy scheme can be deployed in any network based on a topology that allows two connections between a subnet and the backbone. The solution relies on a dynamic routing protocol to provide backbone-level routing around the malfunctioning internetwork link.

Applying fault-tolerant solutions of circulant graphs to multidimensional meshes

Recently, circulant graphs have received a lot of attention; and a new method was proposed for designing fault-tolerant solutions for any given circulant graph. This method works by partitioning the offsets of the graph in many ways; each leads to one or more solutions. By comparing all these solutions, we can find the one with the least node-degree. In this paper, we shall first review this method; and then re-examine its applications to the design of k-fault-tolerant meshes (for all possible values of k). Our results demonstrate that the solutions obtained (for both two and three-dimensional meshes) are efficient.

Architectural support for mode-driven fault tolerance in distributed applications

Many distributed applications exhibit different types of system behaviors, or modes , during the course of their operation. Each such mode may have different functional and non-functional requirements (such as fault tolerance, availability, and security). A static software fault-tolerance solution can not cater to the needs of every mode, and also does not utilize system resources intelligently. A flexible architecture is required to provide dependability that can be tailored for such applications. We propose a novel mode-driven fault-tolerance approach that includes: (i) a generic framework to extend the specification of modes with fault-tolerance requirements, and (ii) a software architecture that uses this description to provide the appropriate fault tolerance for each mode at runtime. We also present a case study using a distributed multi-modal CORBA application to demonstrate the effectiveness of our approach.

Recovery Schemes for Mesh Arrays Utilizing Dedicated Spares

In this paper, new schemes are presented in which the spare nodes of a permanent-fault-tolerant processing array are utilized in their idling state to aid in an online transient-error recovery process. Though spares-based methods are well-known solutions to permanent-fault tolerance, the cost of these solutions and the idling spare capacity during normal operation have limited their widespread use. Manufacturers must be offered fault tolerance solutions which provide useful work at all times. We propose the enhanced utility of spares-based methods by commissioning idling spares (those spares remaining after fabrication and subsequent replacement of faulty units) to perform transient-error recovery tasks. Our scheme will commission idling spares to perform periodic on-line testing (verifying whether system is functioning correctly), and recovery point validation during normal operation. When an error occurs, the spare will perform additional testing to select recovery points. Transient-error recovery is required in harsh environments, such as high radiation, where frequent transient errors are unavoidable. In these environments, the cost of job completion can be extremely high without some form of error recovery. Successful job completion can be attained in environments frequented by error bursts by identifying reliable data through the process of periodic on-line testing. We apply our scheme to a mesh array architecture that has applications in digital signal processing. Simulations highlight the overhead of our schemes in terms of job completion time in environments burdened with frequent transient random errors and burst errors. The proposed strategies for recovery are limited to systems of regular structure. There are many applications in signal and image processing that require array processing in which the various nodes perform similar operations with different data sets. Therefore, it is not necessary to switch the application algorithms for the spares when they perform redundant computation in a staggered mode. While this is a significant feature, there is a small cost associated with presenting the same data to a node as well as a spare. With built-in hardware and reconfiguration switches in the fault tolerant arrays, we believe this cost will be insignificant. Extension of our work to more general systems requires consideration of many issues including system timing, and sub-unit communication & dependence. This is a problem for future research.

Minimized Embedding of Arbitrary Hamiltonian Graphs in Fault-tolerant Graph and Reconfiguration at Faults. I. One-fault-tolerant Structures

The paper proposed approaches to minimized embedding of the Hamiltonian graphs in the enveloping fault-tolerant graph representing the structural model of a fault-tolerant multiprocessor computer system. Failures are regarded as faults of vertices and/or connections between the graph vertices. Mathematical studies rely on the group-theoretical analysis of the characteristics of system structure. It underlies the proposed unique approach to designing the one-fault-tolerant and k-fault-tolerant structures retaining after reconfiguration the logical structure of the original target graph and, therefore, the compiled code of system tasks. The minimum fault-tolerant solutions were obtained for one-fault-tolerant and k-fault-tolerant cycles, simple and diagonal grids, and other popular structures, including arbitrary Hamiltonian graphs for which solutions are of minimized nature. Consideration was given to the algorithms of reconfiguration after arbitrary single and multiple faults. Restoration after faults is very simple; it is based on small tables of the group of system automorphisms which enable correct restoration of the system “at the level of theorems” without either static or dynamic additional verification of the reconfiguration process.

Synthesis of fault-tolerant concurrent programs

Methods for mechanically synthesizing concurrent programs from temporal logic specifications obviate the need to manually construct a program and compose a proof of its correctness. A serious drawback of extant synthesis methods, however, is that they produce concurrent programs for models of computation that are often unrealistic. In particular, these methods assume completely fault-free operation, that is, the programs they produce are fault-intolerant. In this paper, we show how to mechanically synthesize fault-tolerant concurrent programs for various fault classes. We illustrate our method by synthesizing fault-tolerant solutions to the mutual exclusion and barrier synchronization problems.

A Fault Tolerance Solution for Sequential and MPI Applications on the Grid

The Grid community has made an important effort in developing middleware to provide different functionalities, such as resource discovery, resource management, job submission or execution monitoring. As part of this effort this paper addresses the design and implementation of an architecture (CPPC-G) based on services to manage the execution of fault tolerant applications on Grids. The CPPC (Con­troller/Pre­com­piler for Portable Checkpointing) framework is used to insert checkpoint instrumentation into the code of sequential and MPI applications. Designed services will be in charge of submission and monitoring of the execution of CPPC-instrumented applications, management of checkpoint files generated by the fault-tolerant applications, and detection and automatic restart of failed executions.

Fault-Tolerant Convergence Routing

This paper presents fault-tolerant protocols for fast packet switch networks withconvergence routing. The objective is to provide fast reconfiguration and continuous host-to-host communication after a link or a node (switch) failure,Convergence routingcan be viewed as a variant ofdeflection routing,which combines, in a dynamic fashion, the on-line routing decision with the traffic load inside the network. Unlike other deflection techniques, convergence routing operates withglobal sense of directionand guarantees that packets will reach or converge to their destinations. Global sense of direction is achieved by embedding of virtual rings to obtain a linear ordering of the nodes. We consider virtual ring embeddings over (i) a single spanning tree, and (ii) over two edge-disjoint spanning trees. Thus, the fault-tolerant solution is based on spanning trees and designed for a switch-based (i.e., arbitrary topology) architecture called MetaNet. In this work, the original MetaNet's convergence routing scheme has been modified in order to facilitate the property that the packet header need not be recomputed after a failure and/or a reconfiguration. This is achieved by having, at the network interface, a translator that maps the unique destination address to a virtual address. It is argued that virtual rings embedded over two-edge disjoint spanning trees increase the fault tolerance for both node and link faults and provides continuous host-to-host communication.

New algorithm for constructing fault-tolerant solutions of the circulant graph configuration

The circulant graph configuration has been used to model several important parallel architectures (such as rings and meshes; for examples). Recently, a new method was developed to construct a k-fault-tolerant solution for any given circulant graph, where k is the number of faulty nodes to be tolerated. A generalization of this method is presented in this paper. We propose a new algorithm which (unlike the earlier method) constructs a large family of k-fault-tolerant solutions, for any given circulant graph (and any value of k). These solutions will then be compared to select the one with the least node-degree. Our algorithm is very efficient to implement, since it requires only a polynomial time to generate and search the solutions. Moreover, our method has useful applications to other parallel architectures, as demonstrated in the paper. We shall examine the application of the method to the problem of designing k-fault-tolerant extensions of (2- and 3-dimensional) meshes; and show that the solutions obtained are very efficient.

Distributed operating systems

In the past five years, distributed operating systems research has gone through a consolidation phase. On a large number of design issues there is now considerable consensus between different research groups. In this paper, an overview of recent research in distributed systems is given. In turn, the paper discusses overall system structure, protection issues, file system designs, problems and solutions for fault tolerance and a mechanism that is rapidly becoming very important for efficient distributed systems design: hints. An attempt was made to provide sufficient references to interesting research projects for the reader to find material for more detailed study.

Performance characterization of the tree quorum algorithm

The tree quorum algorithm, which logically organizes the sites in a system to a tree structure, is an efficient and fault-tolerant solution for distributed mutual exclusion. In this paper, the performance characteristics of the tree quorum algorithm is analyzed. A refinement algorithm is proposed to refine a logical tree structure by eliminating nodes or subtrees which do not improve the performance. Thus the refined tree performs better than the original.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>