Adaptive Systems Graceful Degrading System

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Adaptive Systems Graceful Degrading System

• Paul Li
• Paul.Li_at_cs.cmu.edu

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Fundamental Concept of Dependability

• Failure is an event that occurs when delivered
  service deviates from correct service. (Quality
  of service?)
• Design faults? Physical faults? Or Interaction
  faults?

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Fundamental Concept of Dependability
Natural
Acc
Perm Trans
Environment/System Flux
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System-wide Graceful Degradation (Implicit
Adaptation?)
Updated System Vars
O/A
I/M
System Variables
System Updates
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Scalable System-wide Graceful Degradation
Sub-System
Sub-System
System Variables
O/A
I/M
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Self Healing Problem Space
Rainbow Permanent/Transient Inadequate System
Configuration Stress on the System Configuration
in Distributed Systems Random, arbitrary,
pre-defined Gauges Less than desired quality of
service Perform associated repair On-line
Reconfiguration Long time between
occurrences Quality of service
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Self Healing Problem Space
Open Systems with defined interfaces Assumed to
be complete System knows component presence Data
rates System fluctuates during operation
Elements of distributed systems Heterogeneous
components and resources Dynamic behavior within
expectations Semi-automated System quality of
service Scalability assumes linearity Many
clients and servers in distributed systems