Methods, systems and devices are described to improve the storage and retrieval of video content. The general concepts set forth herein could be used in any video storage system that uses disk drives to store video content, including remote or local storage digital video recorders (DVRs) and the like.

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.

According to one embodiment, a magnetic disk device includes a disk, a write head, a write processing unit selecting a shingled magnetic recording, a determination unit, and a refresh processing unit. The determination unit determines whether a quality-degraded recording sector exists in all recording sectors in each of the bands. If it is determined that a target band including the quality-degraded recording sector exists in the bands, the refresh processing unit refreshes target recording sectors. The target recording sectors include the quality-degraded recording sector. In the target band, the number of the target recording sectors is less than the number of all recording sectors.

According to one embodiment, a magnetic disk device includes a disk, a write head, a write processing unit selecting a shingled magnetic recording, a determination unit, and a refresh processing unit. The determination unit determines whether a quality-degraded recording sector exists in all recording sectors in each of the bands. If it is determined that a target band including the quality-degraded recording sector exists in the bands, the refresh processing unit refreshes target recording sectors. The target recording sectors include the quality-degraded recording sector. In the target band, the number of the target recording sectors is less than the number of all recording sectors.