Abstract: A method is disclosed for managing the performance of shared computing resources in furtherance of delivering on-demand IT services to multiple customers. The inventive method comprises predicting the performance of resources allocated among the customers to minimize performance related problems; preventing performance related problems by evaluating the impact of changes in resource allocations; reacting to performance alerts to resolve performance related problems; and determining the appropriate level of resource performance needed in service level agreements, and that these requirements detailed in the service level agreements are achieved. This Performance Management method ensures that the demands of the customers are not affected by the allocation and utilization of the shared IT resources.