Reliability and SHARPE
Outline 1. What is Reliability? 2. How can you evaluate it? 3. What is SHARPE? 4. Usage of SHARPE
What is Reliability? • how long a system is continuously operational • ability to function correctly over a specified period of time
Why is it so important? • if system is unreliable, suffer a great loss • affect the performance • no system is perfect, so we need to evaluate how reliable of it and make improvement
Types of reliability For a computer system, we can define 2 types: • Hardware reliability • Software reliability
How can you evaluate it? • simulation model - program whose execution mimics the dynamic behavior or the modeled system • analytic model - Make a mathematical prediction of the system reliability
Simulation Advantages: • predict system behavior without having to build and measure a system Disadvantages: • time consuming
What is SHARPE? • Symbolic Hierarchical Automated Reliability and Performance Evaluator • allows users to construct and analyze performance, reliability, availability and performability models
Advantages • once set up the model, it can obtain the information easily and quickly • easy to carry out sensitivity analysis • not time-consuming • easy to write the input file
How to use? • After building the analytic model, then write a input file for the model • input file contains: - state the model type - describe the system - analyze the result
Example Below is the reliability block diagram of a system consisting 8 components: C D A B C E D C
Input file 1 2 3 4 5 6 7 8 9 10 11 12 13 14 block 1 a comp A exp(0. 05) comp B exp(0. 01) comp C exp(0. 3) comp D exp(0. 25) comp E exp(0. 1) parallel three. C C parallel two. D D D series sys 1 A B three. C two. D E end cdf(block 1 a) expr value(10; block 1 a) end
Analysis • After an input file is ready, run the SHARPE and it will produce the result • carry out sensitivity analysis • by changing different mean to failure rate, you can obtain different combinations of result
How does it link to my research? • in my research, SHARPE is used to analyze the reliability of networkcentric environment • with different combinations of probability function, compared with the traditional computing environment
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