High-Performance Computing (HPC) and other research cluster computing resources provided by universities can be useful supplements to the collaboration’s own WLCG computing resources for data analysis and production of simulated event samples. The shared HPC cluster "NEMO" at the University of Freiburg has been made available to local ATLAS users through the provisioning of virtual machines incorporating the ATLAS software environment analogously to a WLCG center. In addition to the provisioning of the virtual enviroment, the talk describes the on-demand integration of these opportunistic resource into the Tier-3 scheduler in a dynamic way. Resources are scheduled using an intermediate layer that monitors requirements and requests the resources needed .
The performance of the virtualized environment is evaluated. Recent developments on monitoring and work towards a more flexible scheduling of opportunistic resources are discussed. This flexibility is essential due to the different requirements needed for various data analysis tasks.