Test und Dependability (3V1Ü)
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(G. Kemnitz)
IT systems automate intellectual tasks: operational procedures
control of processes and machines, design tasks, ... The basic requirement for use is
dependability.
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Key to this are checks and the
and the elimination of detected deficiencies on three levels::
- during design and manufacturing (fault prevention),
- before use and during maintenance (troubleshooting), and
- during operation (fault tolerance, damage prevention).
A key role here is played by the type and scope of the tests carried out and a test-oriented design as a prerequisite for ensuring that a system can be tested sufficiently. The content and learning objective of the lecture are the description of and measures for ensuring the dependability
of systems consisting of hardware and software: monitoring, tests, problem elimination iterations, ...
In practice, this is one of the most expensive and time-consuming tasks in the development and operation of IT systems.
Target audience of the lecture:
Master of Computer Science and interested students from other degree programmes
Credits: (ECTS): 6
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Slide sets [dt]
[S] -- Slide sets, [H] -- Handouts for printing.
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[S1]
Hazards, countermeasures and parameters
- Introduction
- Dependability: service model, availability, reliability, safety.
- Dealing with malfunctions: Monitoring, format checks, value checks,
handling of detected malfunctions, dependability improvement.
- Fault elimination: Elimination iteration, Fault diagnosis and isolation,
Test, stuck-at faults, reliability improvement, maturing processes,
modular test, yield and defect level.
- Fault prevention: fault emergence, determinism and randomness,
projects and process models, quality and creativity.
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[S2]
Probabilities
- Probabilities: definition and estimation, chained events,
fault tree analysis, Markov chains.
- Fault detection: without and with memory, fault modelling.
- Troubleshooting: replacement, repair, maturing processes.
- Fault emergence.
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[S3]
Distributions
- Distribution: Characteristics, Linear transformation, distribution of counts
- Approximations for count distributions: Binomial distribution,
Poisson distribution, Range estimation for Poisson distributed random
variables, normal distribution, Range estimation for normally distributed
random variables, variance increase, Range estimation with dependencies.
- Mixed distribution: properties, applications, range estimates with
Chebyshev's inequality.
- Pareto distribution: properties, fault detection length, damage due to malfunctions.
- Gamma and exponential distribution
- Failures: Parameters, pre-ageing, reserve units, maintenance.
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Tests and checks
- Test: inspection, function test, digital circuits, software, printed circuit boards.
- Monitoring: comparison, information redundancy, fault detecting codes,
check indicators, protocols, time monitoring, invariants, syntax.
- Fault tolerance: error-correcting codes, RAID and backup, redundancy, system solutions.
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Circuit test and self-test
- Fault modelling: circuit faults, local faults, fault models for digital circuits, detection relationships.
- Tests search: Fault simulation, D-algorithm, implication test, search
space structuring, complex function blocks, sequential circuits, memory test.
- Self-test: pseudo-random register, signature register, self-test with LFSR, fault-oriented weighting,
RAM self-test.
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Software
- Programming language: data objects, control flow, malfunction handling, test.
- Design process: Software architecture, design flow, testable requirements, coding and testing..
- Test selection: Mutations, control flow, def-use chains, equivalence classes, UW graph, automata.
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Exercises
References
News:
Old exams.
Autor: gkemnitz, Letzte Änderung: 22.10.2024 13:44:42