@article {18566,
	title = {Impact of Failure Prediction on Availability: Modeling and Comparative Analysis of Predictive and Reactive Methods},
	journal = {IEEE Transactions on Dependable and Secure Computing},
	year = {2018},
	pages = {1-1},
	abstract = {Predicting failures and acting proactively have a potential to improve availability as a correct prediction and a successful mitigation may bring a reward resulting in decrease of downtime and availability improvement. But, conversely, each incorrect prediction may introduce additional downtime (penalty). Therefore, depending on the quality of prediction and the system parameters, predictive fault-tolerance methods may improve or may degrade availability in comparison to the reactive ones. We first derive taxonomies of fault-tolerant techniques and policies to differentiate between reactive and proactive policies that are further classified as systematic and predictive. To evaluate whether a predictive policy improves availability or not, we derive an analytical model for availability quantification. We use Markov chains to extend steady-state availability equation to include: precision and recall, penalty and reward, mitigation success probability and potential failure rate increase due to the prediction load. We also derive A-measure to optimize failure prediction for increasing availability. In our conclusion, precision and recall have comparable impact on availability as changing MTTF and MTTR. To validate the model we also simulate and analyze availability of a virtualized server with exponential distribution of failure and repair rates.},
	keywords = {Analytical models, availability, Computational modeling, failure, fault tolerance, Fault tolerant systems, Mathematical model, modeling, Optimization, prediction, predictive, Predictive models, proactive, Servers},
	issn = {1545-5971},
	doi = {10.1109/TDSC.2018.2806448},
	author = {Kaitovi{\'c}, Igor and Malek, Miroslaw}
}
@conference {17729,
	title = {A Model for the Evaluation of User-Perceived Service Properties},
	booktitle = {International Symposium on Parallel Distributed Processing, Workshops and Phd Forum (IPDPSW)},
	year = {2013},
	month = {May},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Boston, Massachusetts, USA},
	abstract = {An ever-increasing number of both functional and non-functional requirements has resulted in growing system complexity which demands new solutions in system modeling and evaluation. As a remedy, service-oriented architecture (SOA) offers services as basic building elements of system design. Service dependability is highly dependent on the properties of the underlying information and communications technology (ICT) infrastructure. This is especially true for the user-perceived dependability of a specific pair service client and provider as every pair may utilize different ICT components. We provide a model for the description of ICT components and their non-functional properties based on the Unified Modeling Language (UML). Given a service description, a network topology model and a pair service client and provider, we propose a methodology to automatically identify relevant ICT components and generate a user-perceived service infrastructure model (UPSIM). We demonstrate the feasibility of the methodology by applying it to parts of the service network infrastructure at Universit{\`a} della Svizzera italiana, Switzerland. We then show how this methodology can be used to facilitate user-perceived service dependability analysis.},
	keywords = {availability, design engineering, metamodeling, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	isbn = {978-0-7695-4979-8},
	doi = {10.1109/IPDPSW.2013.163},
	url = {http://andreas-dittrich.eu/2013/03/a-model-for-the-evaluation-of-user-perceived-service-properties},
	author = {Dittrich, Andreas and Kaitovi{\'c}, Igor and Murillo, Cristina and Rezende, Rafael}
}
@inbook {17731,
	title = {Model-Driven Evaluation of User-Perceived Service Availability},
	booktitle = {Dependable Computing},
	series = {Lecture Notes in Computer Science},
	volume = {7869},
	year = {2013},
	month = {May},
	pages = {39-53},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	abstract = {Service-oriented architecture (SOA), which proposes services as basic building elements of system design, has emerged as an approach to master growing system complexity. However, it remains difficult to evaluate dependability of such distributed and heterogeneous functionality as it depends highly on the properties of the enabling information and communications technology (ICT) infrastructure. Moreover, every specific pair service client and provider can utilize different ICT components, constituting for the user-perceived view of a service. We provide a model-driven methodology to automatically create reliability block diagrams of such views. Given a service description, a network topology model and a pair service client and provider, it identifies relevant ICT components and generates a user-perceived service availability model (UPSAM). We then use this UPSAM to calculate the steady-state availability of different views on an examplary mail service deployed in the network infrastructure of University of Lugano.},
	keywords = {availability, design engineering, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	issn = {978-3-642-38788-3},
	doi = {10.1007/978-3-642-38789-0_4},
	url = {http://andreas-dittrich.eu/2013/04/model-driven-evaluation-of-user-perceived-service-availability},
	author = {Dittrich, Andreas and Rezende, Rafael},
	editor = {Vieira, Marco and Cunha, Jo{\~a}o Carlos}
}
@conference {17846,
	title = {User-Perceived Instantaneous Service Availability Evaluation},
	booktitle = {19th Pacific Rim International Symposium on Dependable Computing (PRDC)},
	year = {2013},
	month = {12/2013},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Vancouver, British Columbia, Canada},
	abstract = {Today{\textquoteright}s businesses rely ever more on dependable service provision deployed on information and communications technology (ICT) infrastructures. Service dependability is highly influenced by the individual infrastructure component properties. Combining these properties for consistent dependability analysis is challenging as every service requester might use a different set of components during service usage, constituting the user-perceived view on a service. This paper presents a methodology to evaluate user-perceived instantaneous service availability. It uses three input models: (1) The ICT infrastructure, with failure rates, repair rates and deployment times of all components, (2) an abstract description of complex hierarchical services, (3) a mapping that contains concrete ICT components for the service pair requester and provider, as well as their existing replicas, and a duration of usage. The methodology then automatically generates an availability model from those parts of the ICT infrastructure needed during provision for the specified pair. To calculate instantaneous availability, the age of the ICT components, the order and time of their usage during service provision are taken into account. The methodology supports generation of different availability models, we demonstrate this by providing reliability block diagrams and fault-trees. We demonstrate the feasibility of the methodology by applying it to parts of the network infrastructure of Universit{\`a} della Svizzera italiana, Switzerland.},
	keywords = {availability, Client-server systems, Distributed computing, fault tolerance, modeling},
	doi = {10.1109/PRDC.2013.49},
	url = {http://andreas-dittrich.eu/2013/08/user-perceived-instantaneous-service-availability-evaluation},
	author = {Rezende, Rafael and Dittrich, Andreas and Malek, Miroslaw}
}
