A method, apparatus, system, and signal-bearing medium that, in an embodiment, simulate allocation of a simulated resource to simulated partitions in a simulated logically-partitioned computer and determine whether the allocation conflicts. The simulation may include summing amounts of the simulated resource for the simulated partition in an order, where the order of the simulated partitions is received via a user interface. In various embodiments, the allocation may conflict if the allocation exceeds the capacity of the simulated logically-partitioned computer or if the simulated resource is restricted to exclusive allocation. The result of the simulation, including whether the allocation conflicts, is presented via the user interface. In various embodiments, the simulated resource may be memory, an I/O controller, or a storage device.