A method and apparatus for determining the number and location of monitoring entities in a distributed system is disclosed. The method comprising the steps of automatically generating a causality mapping model of the dependences between causing events at the nodes of the distributed system and the detectable events associated with a subset of the nodes, the model suitable for representing the execution of at least one system operation, reducing the number of detectable events in the model, wherein the reduced number of detectable events is suitable for substantially representing the execution of the at least one system operation; and placing at least one of the at least one monitoring entities at selected ones of the nodes associated with the detectable events in the reduced model. In another aspect, the processing described herein is in the form of a computer-readable medium suitable for providing instruction to a computer or processing system for executing the processing claimed.