Dynamic Adaptation of Temporal Event Correlation for QoS Management in Distributed Systems

Temporal event correlation is essential to managing quality of service in distributed systems, especially correlating events from multiple components to detect problems with availability, performance, and denial of service attacks. Two challenges in temporal event correlation are: (1) handling lost events and (2) dealing with inaccurate clocks. We show that both challenges are related to event propagation delays that result from contention for network and server resources. We develop an approach to adjusting the timer values of event correlation rules based on propagation delays in order to reduce missed alarms and false alarms. Our approach has three parts: an infrastructure for real-time measurement of propagation delay, a statistical approach to estimating propagation delays, and a controller that uses estimates of propagation delays to update timer values in temporal rules. Our approach eliminates the need for manual adjustments of timer values. Further, studies of a prototype implementation suggest that our approach produces results that are at least as good as an optimal fixed adjustment in timer values