A method, executed by at least one processor, includes receiving a migration request for a plurality of files, assigning files of the plurality of files that are smaller than a selected size to one or more small-file secondary storage devices, assigning files of the plurality of files that are larger than the selected size to one or more large-file secondary storage devices, and initiating migration of the plurality of files from one or more primary storage devices to the secondary storage devices to which they are assigned. A corresponding computer program product and computer system are also disclosed herein.