When restoring a partition over an existing one, the target partition is deleted from the disk along with its entry in the target disk MBR. Then, with the preserve_mbr option, the restored partition’s entry will occupy the upper empty position in the target disk MBR. Thus, the target disk MBR is preserved. If not specified, the restored partition’s entry will occupy the same position as in the source disk MBR saved in the image. If the position is not empty, the existing entry will be moved to another position.