Practical Reports on Dependability Manifestation of System Failure Site unavailability System...
-
Upload
hollie-hoover -
Category
Documents
-
view
214 -
download
0
Transcript of Practical Reports on Dependability Manifestation of System Failure Site unavailability System...
![Page 1: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/1.jpg)
![Page 2: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/2.jpg)
Practical Reports on Dependability
![Page 3: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/3.jpg)
Manifestation of System Failure
• Site unavailability
• System exception /access violation
• Incorrect result
• Data loss/corruption
• Slow down
![Page 4: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/4.jpg)
PAGE UNAVAILABLE
![Page 5: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/5.jpg)
PAGE UNAVAILABLE
![Page 6: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/6.jpg)
System Exception
![Page 7: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/7.jpg)
Performance Slowdown
![Page 8: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/8.jpg)
DOWNTIME
unplanned20 %
planned80 %
15% contribution
![Page 9: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/9.jpg)
DOWNTIME
unplanned20 %
planned80 %
![Page 10: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/10.jpg)
DOWNTIMEunplanned
20 %
planned80 %
other20 %
software/human
80 %
![Page 11: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/11.jpg)
UNPLANNED DOWNTIME
other20 %
software/human
80 %
![Page 12: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/12.jpg)
UNPLANNED DOWNTIMEother20 %
software/human
80 %
software40 %operator
40 %
other20 %
![Page 13: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/13.jpg)
UNPLANNED DOWNTIME
software40 %operator
40 %
other20 %
![Page 14: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/14.jpg)
Software Errors
Triggers
• Resource exhaustion
• Logical errors
• System Overload
• Recovery code
• Failed upgrade
![Page 15: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/15.jpg)
Logical Error
![Page 16: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/16.jpg)
SYSTEM OVERLOAD
![Page 17: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/17.jpg)
Operator Errors
Triggers
• Configurational– Incorrect parameter setting
• Procedural– Omit/inncorect maintainance action
• Miscellaneous
![Page 18: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/18.jpg)
FAILURE
DURATION• Short (minutes)• Long (weeks)
– Implies large fault chains
FREQUENCY
• Permanent (down until problem fixed)
• Transient (resolves without
intervention)
• Intermittent (trasient + occasional)
SCOPE• Entire system
• Parts of the System
![Page 19: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/19.jpg)
Fault Chains
• ”the series of component failures that led up to a user-visible failure”
• Uncoupled– Independent failures
• Tightly Coupled– Cascading/corelated
failure
![Page 20: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/20.jpg)
Non-Malicious Software Failure
• Most Common Causes– Routine maintenance– Software upgrade– System integration
• Other Causes– System overload– Resource exaustsion– Complex fault tolerant routines
![Page 21: Practical Reports on Dependability Manifestation of System Failure Site unavailability System exception /access violation Incorrect result Data loss/corruption.](https://reader035.fdocuments.in/reader035/viewer/2022062517/56649ef45503460f94c0806b/html5/thumbnails/21.jpg)
”ROUTINE” MAINTAINANCE
• Danske Bank 2003– March 11: routine operation to replace a defective
electrical unit in IBM DB2 disk system– System failure: Disks becomes inaccessable – 6 hours later: system restarted– March 12: Batch systems running incorrectly– Three More errors discovered:
1. Recovery process on several tables won’t start2. Recovery jobs won’t run symultaneously3. Recovery jobs can’t reastablish data in tables
– March 14: All data recovered and system functional