Online detection of failures generated by storage simulator
Modern large-scale data-farms consist of hundreds of thousands of storage devices that span distributed infrastructure. Devices used in modern data centers (such as controllers, links, SSD- and HDD-disks) can fail due to hardware as well as software problems. Such failures or anomalies can be detected by monitoring the activity of components using machine learning techniques. In order to use these techniques, researchers need plenty of historical data of devices in normal and failure mode for training algorithms. In this work, we challenge two problems: 1) lack of storage data in the methods above by creating a simulator and 2) applying existing online algorithms that can faster detect a failure occurred in one of the components.
We created a Go-based (golang) package for simulating the behavior of modern storage infrastructure. The software is based on the discrete-event modeling paradigm and captures the structure and dynamics of high-level storage system building blocks. The package's exible structure allows us to create a model of a real-world storage system with a configurable number of components. The primary area of interest is exploring the storage machine's behavior under stress testing or exploitation in the medium-or long-term for observing failures of its components.
To discover failures in the time series distribution generated by the simulator, we modified a change point detection algorithm that works in online mode. The goal of the change-point detection is to discover differences in time series distribution. This work describes an approach for failure detection in time series data based on direct density ratio estimation via binary classifiers.
The paper focuses on analysis of investments in development of performance management systems that provide information support of strategic management. Such systems do not allow estimating the results of their development in financial terms, so traditional methods of investment appraisal are inapplicable. In this case, comparison of investments with non-financial values seems reasonable. Taking into consideration stochastic factors, the simulation approach is recommended. The purpose of the paper is to develop a discrete-event simulation model for analyzing of results of performance management systems development programs implementation. The appropriate tasks include description of key elements of the model, as well as recommendations regarding evaluation of development programs and selection of the preferable one. The model relies on timed stochastic Petri nets, where time lags are described in terms of holding durations assigned to output arcs. All the time lags may be either deterministic or stochastic. The simulation model presented in the paper allows analysis of investments in performance management systems development. The model contains description of projects, relations between them, as well as impact of the projects on maturity of the performance management system and appropriate financial metrics. The simulation model makes possible calculating generic measures of effectiveness, resource usage and time characteristics of performance management systems development programs. If there are several alternative development programs, these measures may be used for comparison of the programs and selection of one of them for implementation.
Publications on modeling of project management systems dynamics are reviewed. Studies analyzed mainly consider dynamics of project management systems in the organizational environment of projects implementation. History of project management dynamics modeling is presented as well as classification of existing dynamic models. The review includes papers on the following groups of modeling methods: for optimal and sustainable project scheduling, for discrete event simulation and for macro-modeling based on system dynamics. Also analyzed are current trends of modeling methods development in reference to research of dynamics of project management systems.
Importance. The paper focuses on development of performance management systems that provide information support of corporate governance and strategic management. At present, any integral methodology of such systems’ development management is not available, so establishing of principles and approaches to evaluation and selection of their development programs seems actual.
Objectives. The purpose of this paper is to advance a methodological approach to evaluating of performance management systems development programs. Appropriate tasks include elicitation of features of development programs for such systems, as well as definition of methods and models allowing evaluation of alternative development programs and selection of one of them for implementation.
Methods. The paper relies on analysis of existing methods of development management for organizational and technical systems. A conceptual model of a performance management system development program is established taking into account the nature and features of discrete event simulation.
Results. Specificity of evaluation of performance management systems development programs includes impossibility of financial estimation of their results (and, consequently, inapplicability of traditional investment analysis methods), as well as significant influence of uncertainty. Such programs should be evaluated relying on dynamics of the systems’ maturity (in comparison with certain maturity levels), with application of discrete event simulation. The main elements of the model are projects, events, development metrics and financial metrics. The results of simulation are applied for evaluation of development programs according to effectiveness and economy criteria. These criteria may be supplemented by qualitative aspects estimated by experts within multiple criteria decision analysis.
Conclusions and Relevance. Evaluation of performance management systems development programs should rely on the dynamics of such systems’ maturity levels and appropriate financial metrics, taking into consideration stochastic nature of some of parameters. A conceptual simulation model of the system’s development is advanced; principles of development programs evaluation based on simulation results are justified.
This paper describes a discrete-event simulation model for estimating resources for handling and storing slabs in a metallurgical plant. The model is implemented using Anylogic 8 software. We describe simulation experiments for estimating material handling equipment performance and capital cost reduction.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traﬃc is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the ﬁnal node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a ﬁnite-dimensional system of diﬀerential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of diﬀerential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
Existing approaches suggest that IT strategy should be a reflection of business strategy. However, actually organisations do not often follow business strategy even if it is formally declared. In these conditions, IT strategy can be viewed not as a plan, but as an organisational shared view on the role of information systems. This approach generally reflects only a top-down perspective of IT strategy. So, it can be supplemented by a strategic behaviour pattern (i.e., more or less standard response to a changes that is formed as result of previous experience) to implement bottom-up approach. Two components that can help to establish effective reaction regarding new initiatives in IT are proposed here: model of IT-related decision making, and efficiency measurement metric to estimate maturity of business processes and appropriate IT. Usage of proposed tools is demonstrated in practical cases.