Modern distributed systems are characterized by a growing complexity of their architecture, functionalities and workload. This complexity, and in particular significant workloads, often lead to quality of service loss, saturation and sometimes unavailability of on-line services. To avoid troubles caused by important workloads and fulfill a given level of quality of service (such as response time), systems need to \emph{self-manage}, for instance by tuning or strengthening one tier through replication. This autonomic feature requires performance modelling of systems. In this objective, we developed an automatic identification process providing a queuing model for a part of distributed system considered as black box. This process is a part of a general approach targetting self-sizing for distributed systems and is based on a theoretical and experimental approach. In this report, we show how to derive automatically the performance model of one black box considered as a constituent of a distributed system, starting from load injection experiments. This model is determined progressively, using self-regulated test injections, from statistical analysis of measured metrics, namely response time. This process is illustrated through experimental results.