The Many Faces of Software UnReliability Taz Daughtrey ©2011 ASQ & T. DAughtrey Presented live on Jan 12 th , 2012 http://reliabilitycalendar.org/ The_Reliability_Calendar/ Webinars_-_English/Webinars_- _English.html
ASQ RD Many Faces of Software un-Reliability
Dec 19, 2014
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The Many Faces of Software
UnReliabilityTaz Daughtrey©2011 ASQ & T. DAughtrey
Presented live on Jan 12th, 2012
http://reliabilitycalendar.org/The_Reliability_Calendar/Webinars_-_English/Webinars_-_English.html
ASQ Reliability Division English Webinar SeriesOne of the monthly webinars
on topics of interest to reliability engineers.
To view recorded webinar (available to ASQ Reliability Division members only) visit asq.org/reliability
To sign up for the free and available to anyone live webinars visit reliabilitycalendar.org and select English Webinars to find links to register for upcoming events
http://reliabilitycalendar.org/The_Reliability_Calendar/Webinars_-_English/Webinars_-_English.html
The Many Faces ofSoftware Unreliability
Taz Daughtrey
Data and Analysis Center for Software
James Madison University
© 2011 Quanterion Solutions, Inc.
The Many Faces ofSoftware Unreliability
ASQ Reliability Division WebinarJanuary 12, 2012
Defining software reliability
Measuring software reliability
Achieving software reliability
The future
Errors => Defects => Failures
The Many Faces of Software Unreliability
Defining software reliability
Reliability: does what is expected
Unreliability: doesn’t do what is expected
unavailable
compromised
unsafeincorrect
The Many Faces of Software Unreliability
Measuring software reliability
Reliability: measured in……success/failure probability
…Mean Time To Failure
Mean Time To Repair
mission failure
$ lossrisk exposure
measured in …
Risk Exposure =
Probability of occurrence
X
Consequence of occurrence
Risk Avoidance
X
Consequence of occurrence
Risk Exposure =Risk Exposure =
ProbabilityProbability of of occurrenceoccurrence
Risk Mitigation
Risk Exposure =
Probability of occurrence
X
ConsequenceConsequence of occurrence of occurrence
R O I = return
investment
R O R I = risk exposure reduction
reliability investment
Risk Avoidance costs $3 x 103
4 x 10 4 x 10 --
4 4
$4 x 103
risk exposure reduction of $104 -$4 x 103 = $6 x 103
Risk Avoidance costs $3 x 103
4 x 10 4 x 10 --
4 4
$4 x 103
risk exposure reduction of $104 -$4 x 103 = $6 x 103
Return On Risk Exposure Reduction =$6 x 103 / $3 x 103 = 2.0
Risk Mitigation costs $5 x 103
10 10 -3 -3 ProbabilityProbability of occurrence of occurrence
$3 x 106
$3 x 103
risk exposure reduction of $104 -$3 x 103 = $7 x 103
Risk Mitigation costs $5 x 103
10 10 -3 -3 ProbabilityProbability of occurrence of occurrence
$3 x 106
$3 x 103
risk exposure reduction of $104 -$3 x 103 = $7 x 103
Return On Risk Exposure Reduction =$7 x 103 / $5 x 103 = 1.4
The Many Faces of Software Unreliability
Achieving software reliability
Software Reliability Engineering
E Establish quantitative reliability targets
Construct usage profiles of operational system
Test statistically to predict system reliability
Software Reliability Estimation+
Reliability Growth Modeling
Lifecycle Software Reliability Measurements
Statistical Modeling and Estimation of Reliability Functions for Software
Set measureable targets
Design, implement
Conduct appraisals
Release? Rework?
reviews tests
stakeholder agreement operational profiles
verifiable requirements fault-tolerant design
FAULT ENCOUNTER
FAULTSOURCE
intentional
accidental
intentionalaccidental
FAULT ENCOUNTER
FAULTSOURCE
intentional
accidental
intentionalaccidental
malicious
tradeoffs
Attack + Countermeasure Tree
The Many Faces of Software Unreliability
The future of software reliability
DACS Software Reliability Initiative
= “Roadmap to Dependability”
DACS projected products:
Handbook series Software Reliability and Security Testing Software Reliability and Security Specification
Software Reliability and Security Assessment and Improvement
Training offerings Software Reliability and Security Fundamentals
+ industry-specific modules
Research support
ongoing mentoring
on-the-job application
management-sponsored projectinitial class session
follow-up sessions
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