A computer-implemented method for migrating file data in a hierarchical storage environment includes: detecting that a file recalled from a magnetic tape to a primary storage device was modified; determining whether the magnetic tape from which the file was recalled is loaded in a tape drive upon detecting that the file was modified; responsive to determining that the magnetic tape from which the file was recalled is loaded in the tape drive upon detecting that the file was modified, appending only a modified portion of the file to the magnetic tape; and responsive to determining that the magnetic tape from which the file was recalled is not loaded in the tape drive upon detecting that the file was modified, appending the file in its entirety, including the modified portion of the file and any unmodified portions of the file, to a different magnetic tape.