Disaster Tolerant Computing and Communications Systems Mitch Thornton Steve Szygenda

Outline Definitions Motivation Modeling Approaches Conclusion/Future Work

Motivation Many Systems Vulnerable to Disasters Cannot Use Principle of Redundancy Fault Tolerance Models May Not be Applicable to Disasters Disaster Tolerance is Crucial for Security and Infrastructure Robustness

Disaster Definition Disaster: an event that can cause a system-wide malfunction as a result of one or more failures within a system. Disasters may occur due to a single-point failure or by a plurality of single-point failures that occur either simultaneously, or nearly simultaneously in a temporal sense and may be caused from either a man-made or natural event.

Catastrophe Definition Catastrophe: an event that can happen as the result of the occurrence of a disaster and cause a system to function improperly. Catastrophe avoidance is the goal of disaster tolerance.

Related Concepts Disaster Recovery –Ability to Resume Normal Operation After Occurrence of Disaster Disaster Avoidance –System Incorporates Techniques that Prevent System-wide Failure Fault Tolerance –Mechanisms/Techniques in a System to Allow Functionality in the Presence of a Fault –Fault Model Used to Determine Fault Tolerant Mechanisms Disaster Tolerance –Mechanisms/Techniques in a System to Allow Functionality in the Presence of a Disaster –Disaster Model Used to Determine Disaster Tolerant Mechanisms

Disaster Models Chaos Theory –Applicable to Large Complex Non-linear Dynamic Systems with Feedback –Can Model Sudden Transitions in Dynamic Systems –A Disaster is a Sudden Transition in a Dynamic System –Successfully Used to Model Dynamic Interactions of Power Generators on Electric Grid in 1982

Two Generator Fractal* *James Thorp, Cornell University Each Point: Phase Angle wrt Reference Gen. Light Blue: Grid Stability Other Colors: Grid Vulnerable or Unstable Small Changes: Can Cause Sys. Instability (Disaster)

Disaster Models Catastrophe Theory –Theory in Vogue in 50’s (Rene Thom) –System is Modeled as Multidimensional Smooth Surface Affected by Classes of Singularities –A Disaster is Modeled as a Singularity that Occurs in Normal System Operation –Example is the Use of Catastrophe Theory to Predict the Formation of a Planet when Two Stars Stray Close Together and Gas is Pulled from One to the Other

Conclusions Disasters, Catastrophes Defined as Events Disaster Models Needed to Provide Disaster Tolerance Candidate Mathematical Tools Defined for Disaster Models

Proposed Future Work Choose Candidate Large System with Disaster Data Formulate and Calibrate Disaster Model Apply Disaster Model to Other Large Systems to Identify Critical Components Model Systems with More Robust Critical Components (Redundancy?) and Apply Disaster Model