In a first part, we will present the basics of tracing and what the major issues are. We will present some of the main tracing environments and try to compare them. We will focus on extrae and present some mechanisms that allow to increase scalability. We will also describe some of the analysis capabilities motivating such mechanisms and how to use them. In particular, we will present a couple of recent developments with clustering and processing sampled data ("folding"). We will illustrate the resulting analysis with paraver. In a second part, a few traces will be provided and attendees will have the opportunity of analyzing them or even to obtain traces from their own code if time allows