Strategies for Problem Determination using Probing

As distributed systems continue to grow in size and complexity, scalable and cost-efficient techniques are needed for performing tasks such as problem determination and fault diagnosis. In this paper, we address these tasks using probes, or test transactions, which replace traditional “passive” event-correlation techniques with a more active, real-time information-gathering approach. We provide a theoretical foundation and a set of practical techniques for implementing efficient probing strategies the main issue is minimizing the cost of probing while maximizing the diagnostic accuracy of the probe set. We show that finding an optimal probe set is NP-hard and devise polynomial-time approximation algorithms that demonstrate excellent empirical performance, even on large networks. We also implement an active, on-line probing strategy that yields a significant reduction in the probe set size.