1. A data storage manager operational in a data storage subsystem that uses a plurality of data storage elements to store data thereon for a plurality of host processors that are connected to said data storage subsystem, comprising: means for storing a set of logical data storage device definitions that are created from said plurality of data storage elements; means for identifying a set of data storage characteristics appropriate for a present data object; means for comparing said identified set of data storage characteristics with said stored set of logical data storage device definitions; means, responsive to a failure to match said identified set of data storage characteristics with a single one of said stored set of logical data storage device definitions, for creating a new logical device definition using a plurality of said stored set of logical data storage device definitions; and means for storing said present data object on interconnected ones of said plurality of data storage elements that correspond to said new logical device definition.