Storage unit selection for virtualized storage units

Performance information for storage units located at a virtual data center is determined by executing storage administrator logic whose execution is controlled by a management entity different than the virtual data center provider. Performance expectations are automatically determined based on the determined performance information. In response to determining that a particular storage unit is incompatible with performance expectations applicable to the particular storage unit, embodiments cause a reduction in utilization of the particular storage unit. Based on determined performance information, another embodiment determines that a performance pattern indicating a physical co-location of a first storage unit and a second storage unit has occurred. In response to determining that the performance pattern indicating a physical co-location of a first storage unit and a second storage unit has occurred, the embodiment disables use of a selected storage unit of the first storage unit or the second storage unit for at least a particular purpose.