A 2 thOS: availability analysis and optimisation in SLAs
Summary (1 min read)
Introduction
- A framework to calculate the availability of partially outsourced IT services in the presence of SLAs and to achieve a cost-optimal choice of availability levels for outsourced IT components while guaranteeing a target availability level for the service.the authors.
- Figure 4 shows one possible scheduling for the failure of the components on which Service1 depends on, resulting in Service1 having an availability of αService1 (0.984).
- To this end the authors distinguish among three types of nodes in a dependency graph: target availability nodes, variable availability nodes and given availability nodes.
- The analysis engine solves the availability analysis problem, described in Section 3.
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References
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1,266 citations
"A 2 thOS: availability analysis and..." refers background in this paper
...the smallest set of combinations of basic events (component failures) which all need to occur for the top event to take place (system failure) [15]....
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884 citations
"A 2 thOS: availability analysis and..." refers background or methods in this paper
...Reliability studies have introduced a number of (by now) standard techniques (e.g. continuous‐time Markov chains (CTMC) [2] and Petri nets [3]) which allow one to compute system availability when the mean time between component failures and the mean time to repair a component is known....
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...To compute the availability of complex systems, CTMC [2] or Petri nets [3] are used....
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...continuous‐time Markov chains (CTMC) [2] and Petri nets [3]) which allow one to compute system availability when the mean time between component failures and the mean time to repair a component is known....
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...Based on the minimal cut set, a combination of combinatorial techniques and CTMC or Petri nets is then used to calculate the system (limiting) availability....
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730 citations
"A 2 thOS: availability analysis and..." refers background in this paper
...We share with FTs the use of minimal cut sets, which in our notation are called dependency sets (see Section 3), but the availability calculation we apply to AND/OR dependency graphs is different from the one used in FTs (for the reason mentioned above)....
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...In FTs, a number of components (called basic events) are linked together to make up a system according to AND/OR relationships....
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...In FTs, the system state is represented by the top event, i.e. the root of the tree....
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...Galileo [20], Coral [21], Relex [22] and BlockSim [23] are tools operating with dynamic FTs....
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...FTs and RBDs are the most used ones....
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