A method of and system for managing a data set stored on units of storage space in a storage facility is disclosed. The method and system may include identifying prospect extents of the data set. The prospect extents may include a first prospect extent stored on a first unit of storage space and a second prospect extent stored on a second unit of storage space. The method and system may include congregating the first prospect extent and the second prospect extent on a destination unit of storage space in the storage facility.