Adaptive Systems Graceful Degrading System Paul Li

Adaptive Systems – Graceful Degrading System Paul Li Paul. Li@cs. cmu. edu

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

Fundamental Concept of Dependability Natural Acc Perm Trans Environment/System Flux

System-wide Graceful Degradation (Implicit Adaptation? ) Software Detection/ Component Monitoring Software Detection/ Monitoring Software Component. Detection/ Software Detection/ Component Monitoring Software Monitoring Component. Detection/ Component Monitoring Updated System Vars I/M System Updates O/A stem les Sy ab ri Va

Scalable System-wide Graceful Degradation Software Detection/ Monitoring Sub-System Component Monitoring Component Software Detection/ Sub-System. Monitoring Component Detection/ Software Monitoring Component I/M O/A stem les Sy ab ri Va

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

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