f33-book-depend-pres-pt1

F33-book-depend-pres - Oct 2009 Part I Introduction Dependable Systems Slide 1 About This Presentation This presentation is intended to support the

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Oct. 2009 Part I – Introduction: Dependable Systems Slide 1
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 2 About This Presentation This presentation is intended to support the use of the textbook Dependable Computing: A Multilevel Approach (traditional print or on-line open publication, TBD). It is updated regularly by the author as part of his teaching of the graduate course ECE 257A, Fault-Tolerant Computing, at Univ. of California, Santa Barbara. Instructors can use these slides freely in classroom teaching or for other educational purposes. Unauthorized uses, including distribution for profit, are strictly prohibited. © Behrooz Parhami Edition Released Revised Revised Revised Revised First Sep. 2006 Oct. 2007 Oct. 2009
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 3 1 Background and Motivation
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 4 “I should get this remote control looked at.”
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 5
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 6 1.1 The Need for Dependability Hardware problems Permanent incapacitation due to shock, overheating, voltage spike Intermittent failure due to overload, timing irregularities, crosstalk Transient signal deviation due to alpha particles, external interference Software problems Counter or buffer overflow Out-of-range, unreasonable, or unanticipated input Unsatisfied loop termination condition Dec. 2004: “Comair runs a 15-year old scheduling software package from SBS International (www.sbsint.com). The software has a hard limit of 32,000 schedule changes per month. With all of the bad weather last week, Comair apparently hit this limit and then was unable to assign pilots to planes.” It appears that they were using a 16-bit integer format to hold the count. June 1996: Explosion of the Ariane 5 rocket 37 s into its maiden flight was due to a silly software error. For an excellent exposition of the cause, see: http://www.comp.lancs.ac.uk/computing/users/dixa/teaching/CSC221/ariane.pdf These can also be classified as design flaws
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 7 The Curse of Complexity Computer engineering is the art and science of translating user requirements we do not fully understand; into hardware and software we cannot precisely analyze; to operate in environments we cannot accurately predict; all in such a way that the society at large is given no reason to suspect the extent of our ignorance. 1 1 Adapted from definition of structural engineering: Ralph Kaplan, By Design: Why There Are No Locks on the Bathroom Doors in the Hotel Louis XIV and Other Object Lessons , Fairchild Books, 2004, p. 229 Microsoft Windows NT (1992): 4M lines of code Microsoft Windows XP (2002): 40M lines of code Intel Pentium processor (1993): 4M transistors Intel Pentium 4 processor (2001): 40M transistors Intel Itanium 2 processor (2002): 500M transistors
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Oct. 2009 Part I – Introduction: Dependable Systems Slide 8 Defining Failure Failure is an unacceptable difference between expected and observed performance.
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This note was uploaded on 12/29/2011 for the course ECE 257a taught by Professor Parhami,b during the Fall '08 term at UCSB.

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F33-book-depend-pres - Oct 2009 Part I Introduction Dependable Systems Slide 1 About This Presentation This presentation is intended to support the

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