Techniques for reducing the time required for erasing specific data recorded on a tape medium. A specific group of records is erased without preliminarily locating the erasure end position. This is carried out by simultaneously utilizing three heads, that is, two read heads and one write head, to detect the erasure end position during data erasure. Various embodiments are applicable to tape media as well as other storage media. Various embodiments are not only applicable as a file system cooperating as a combination of hardware (H/W) and software (S/W), but also applicable in systems, such as databases, that directly use storage without an intermediary file system.