Abstract: An automatic volume block resizer for automatically resizing a volume in a disk drive system. The original volume includes original volume blocks each having an original volume block size, and the resized volume including new volume blocks each having a new volume block size. The volume block resizer comprises means for automatically aligning files contiguously on new volume block boundaries and means for redefining the volume for use with the new volume block size. The file aligning means comprises means for moving original volume blocks to available locations on the volume to create disk space equivalent to the new volume block size and to store the files on the new volume block boundaries. The files are stored contiguously; that is, they are defragmented as they are realigned onto the new volume block boundaries. The realignment is performed through the manipulation of original volume blocks of data.