Consolidated server systems using virtualization involves serious risks of host failures that induce unexpected downs all hosted virtual machines and applications. To protect applications requiring high-availability from unpredictable failures, redundant configuration can be an effective countermeasure. This paper presents a machine placement method for establishing against with less servers. The proposed estimates the requisite minimum number according to performance requirements...

Experts of chance discovery have recognized a new class problems where the previous methods fail to visualize latent structure behind observation. There are invisible events that play an important role in dynamics visible events. An leader communication network is typical example. Such event named dark event. A novel technique has been proposed understand and extend process discovery. This paper presents method "human-computer interactive annealing" for revealing structures along with...

Fault tree analysis (FTA) is a traditional reliability technique. In practice, the manual development of fault trees could be costly and error-prone, especially in case tolerant systems due to inherent complexities such as various dependencies interactions among components. Some dynamic gates, Functional Dependency (FDEP) Priority AND (PAND), are proposed model functional sequential dependencies, respectively. Unfortunately, potential semantic troubles limitations these gates have not been...

Software aging is a phenomenon of progressive degradation software execution environment caused by faults. In this paper, we propose life-extension as an operational countermeasure against and present the mathematical foundations means stochastic modeling. A semi-Markov process used to capture behavior system with analyze system's availability completion times jobs running on it. The can correctly model time-based allows us derive optimal trigger for starting in terms mean job time. We also...

Hybrid hierarchical optical cross-connects enhance the performance/cost ratio of networks by providing transparent (optical) switching sets wavelengths (wavebands) in addition to opaque (electrical) individual wavelengths. As network bandwidth gets cheaper, and performance bottleneck moves nodes, these systems provide an attractive scalable solution for next-generation networks. We describe key technological components (including flexible nonuniform wavebands) hybrid discuss their implications.

Cloud computing is established on advanced software technologies intended to enhance the scalability of infrastructure by making full use commodity servers. The more cloud relies technologies, bugs have significant impacts system availability. Aging-related bugs, which cause accumulation errors in long time execution, often remain even after release a stable version software. This paper investigates bug reports five major open-source projects related and confirms issues about existence...

We present a novel model for collisional energy transfer between ions and neutral molecules in the quadrupole radio-frequency trap. Calculated results quantitatively reproduce dependence of ion temperature T i on buffer gas pressure P n , observed Mg + several collision partners (H 2 He, CH 4 ). It is deduced from that proportional to -1/3 low-pressure range below 10 -6 Torr, good agreement with experimental results.

We consider hierarchical optical networks with different granularities of paths (wavelengths and wavebands). introduce classification layers for routing models in these (separated integrated routing, homogeneous heterogeneous networks, online offline routing). also propose analyze two heuristic aggregation algorithms (online offline) to be used the separate framework. The analysis is based on ring topology; its results are supported by simulations large scale (Europe USA). These demonstrate...

This paper addresses the coverage (including identification and isolation) of irrelevant components in systems with imperfect fault (IFC). In fault-tolerant systems, a single not-covered component may thwart automatic recovery mechanisms, lead to system or subsystem failure. The models that consider effects IFC are known as (CMs). traditional CMs, except those considering functional dependency (a similar concept relevancy but different assumptions semantics), is typically limited faulty...

This paper addresses a method to analyse the covert social network foundation hidden behind terrorism disaster. It is solve node discovery problem, which means discover node, functions relevantly in network, but escaped from monitoring on presence and mutual relationship of nodes. The aims at integrating expert investigator's prior understanding, insight terrorists' nature derived complex graph theory computational data processing. responsible for 9/11 attack 2001 used execute simulation...

This paper presents a high-availability solution to virtualized data center which consists of cluster physical servers and hosted virtual machines (VMs). VMs are typically generated through software called machine monitor (VMM) running on servers. Both VMMs face the risks aging caused by aging-related bugs in may result failures long time execution. To prevent such proactively, we propose combined server rejuvenation technique that performs VM rejuvenations simultaneously with VMM...

This paper presents software life-extension, a new technique for counteracting aging by preventive operation to extend the lifetime of execution. Software is phenomenon progressive degradation execution environment due aging-related faults and it might cause resource depletion resulting in system failures. To affected aging, we use virtual machine execute allocate additional memory upon detection. Although life-extension temporal solution as only postpones occurrence failure, provides...

Experts of chance discovery have recognized a new class problems where the previous methods fail to reveal latent structure behind observation. There are invisible events which play an important role in dynamics visible events. A hidden hub person (an leader) communication network is typical example. This paper presents stable deterministic crystallization algorithm for discovering such The evaluated with test data generated from large scale-free random network. It demonstrated that...

A PAND gate is a special AND of Dynamic Fault Trees (DFTs) where the input events must occur in specific order for occurrence its output event. We present transformation from to an with some dependent conditioning events, called CAND gate, provided that dynamic behavior system can be modeled by (semi-)Markov process. With transformation, DFT only static Boolean logic gates and transformed into fault tree, which opens up way employ efficient combinatorial analysis DFT. In addition, cannot...

Traditional imperfect fault coverage models only consider the (including identification and isolation) of faulty components, they do not irrelevant (operational) components. One potential reason for omission is that in these system generally assumed to be coherent which each component initially relevant. In this paper, we first point out an relevant could become afterwards due failures some other thus it important handling irrelevancy even originally coherent. We propose model (IRCM)...

Methods to solve a node discovery problem for social network are presented. Covert nodes refer the which not observable directly. They transmit influence and affect resulting collaborative activities among persons in network, but do appear surveillance logs record participants of activities. Discovering covert is identifying suspicious where would if became overt. The performance methods demonstrated with test dataset generated from computationally synthesized networks real organization.

This study presents an ANWSER model (asset network systemic risk model) to quantify the of financial contagion which manifests itself in a crisis. The transmission distress is governed by heterogeneous interbank credit and investment portfolio banks. Bankruptcy reproductive ratio system computed as function diversity exposure banks, denseness concentration network. An analytic solution bankruptcy for small derived numerical large obtained. For system, among banks makes more damaging on...

We propose an implementation of a terabits-per-second crossbar-equivalent switch-fabric for packet-switching networks. It consists switch-modules employing semiconductor optical amplifier gates (SOAGs), arrayed waveguide grating routers, and multiple wavelength-channels. offers large modularity small internal loss. The number SOAGs in 256/spl times/256 is one-eighth that conventional switch-fabric. Scalability up to 2.56 Tb/s demonstrated by 10 Gb/s transmission experiment which the input...

A packet/cell-based optical switch-fabric demonstrator has been successfully developed that is upgradable to 2.56 Tb/s throughput. The number of components in a 256/spl times/256 dramatically reduced one-eighth conventional switch-fabric.