Fault tolerance 1‍¥

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  • 1. Fault Tolerance 1 1

2. (Dependability) (reliability), (availability), (safety), (security) (Fault Avoidance) (Fault Masking) (Fault Tolerance) Fault Tolerance 2 3. Fault tolerance system , Failure( ) Fault Tolerance 3 4. Error( ) . Fault( ) . : : , Fault Tolerance 4 5. Fault( ) ,Error( ) ,Failure( ) Fault Tolerance 5 Cause of Error : Fault Subsystem Unintended state : Error Deviation from Intended service : Failure Under specific consideration 6. Fault Tolerance 6 , 7. (loop) . , , ( , , ) Fault Tolerance 7 8. - - Fault Tolerance 8 9. Fault Tolerance 9 10. Fault Tolerance 10 11. Fault Tolerance 11 , ( ) 12. Fault Tolerance 12 , 13. Fault Tolerance 13 1. 2. ATM ( 20 5 ) (ATM) 14. Fault Tolerance 14 Ariane 5 Ariane 4 Ariane 5 , Fault_1 Fault_2 Fault_3 Fault_4 Fault_5 Fault_6 Error_1 Error_2 Failure 15. Consistent failures . . 1 Fail silent Fail stop fail-silent , crash 16. Inconsistent failures . , , (Byzantine) . 1 , 2 , Fault Tolerance , fail-silent , Fault Tolerance 16 17. (N = failure ) Fault Tolerance 17 Fail-silent failure N+ 1 ( ) Consistent failure 2N + 1 ( 5 ) Inconsistent failure 3N + 1 18. , , , Fault Tolerance 18 Ariane5 ariane 5 ariane 4 19. ( / ) ( )* ( ) 95% Coverage process , Fault Tolerance 19 20. : : ( ) MTTF(Mean Time To Failure) MTBF(Mean Time Between Failure) Reliability : e-(1/MTTF) MTTR(Mean Time To Repair) FIT(Failures in Time) : 1*109 Fault Tolerance 20 21. 90 Spirit Opportunity , 1000 6 5 MTTF 5 ( ) MTTR ( ) Fault Tolerance 21 22. Availability : MTTF / MTTF+MTTR Availability Alcatel-Lucent 4ESS : 40 2 3 5ESS 6 9 Fault Tolerance 22 ( ) 100 % 0 3 9 99.9 % 525.6 4 9 99.99 % 52.56 4 9 5 99.995 % 26.28 5 9 99.999 % 5.256 6 9 99.9999 % 0.5256 100 % 0 23. , . (International Reliability Physics Symposium) (Electronic Components and Technology Conference) IEEE (Device and Materials Reliability) (Advanced Packaging) (Solid State Circuits) Fault Tolerance 23 24. , , Handbook of Software Reliability Engineering [Lyu96] Fault tolerance system , Markov , MTTF Fault Tolerance 24 25. Markov , ( ) , : c Markov Unavailability (1-c)2 / + 2( /)2 , >> Fault Tolerance 25 26. & : 30 50 . Fault Tolerance 26 27. Fault Tolerance 27 28. tradeoff ( 6% , 50% ) , TV , . , Fault tolerant 7 Fault Tolerance 28 29. http://www.beinrohr.sk/sxool/3roc/mas/AdSyMod/tsld http://www.utdallas.edu/~ilyen/course/realtime/fau http://i-bada.blogspot.kr/2012/04/mttfmtbf.html?m= Patterns for fault tolerant software , Fault Tolerance 29