Abstract: A method, program product, and data processing system are provided for modifying a cluster in a data processing system, the cluster comprising a plurality of nodes. A monitoring unit monitors resource usage over at least one cycle of a periodic timeframe to obtain monitored resource usage data. A forecasting component forecasts resource usage over a future cycle of the periodic timeframe using the monitored resource usage data to obtain forecast resource usage data. An analysis component analyzes the forecast resource usage data using at least a first rule to determine whether a modification of the cluster is necessary and at least a second rule to determine a time window for the modification of the cluster. A modification component modifies the cluster by adding or removing a node to the plurality of nodes in the time window.