Abstract: A method, a system and a computer program product for selecting a primary controller for a server system based on the services offered by each controller. A primary controller designator (PCD) utility determines the relative importance of a controller based upon the services provided by the controller and the weighted importance assigned to these services. The PCD utility classifies the services provided by a system-controller according to the following: (1) the number of OS partitions a system-controller is able to communicate with; and (2) the number of hardware devices that a controller has access to. The importance of the services is determined by the host OS partition information and the degree of importance of a partition that utilizes/requires the particular service(s). The PCD utility designates a controller as a “Primary” if the designated “Primary” is capable of providing services that are required for the most important OS partitions, according to the classification of controller services.