Disk drive devices using various kinds of disks, such as an optical disk, a magneto-optical disk, and a flexible magnetic disk, have been known in the art. In particular, a hard disk drive (HDD) has been widely used as a storage device of a computer and has been one of indispensable disk drive devices for current computer systems. Moreover, the HDD has found widespread application such as a removable memory used in a moving image recording/reproducing apparatus, a car navigation system, a cellular phone, or a digital camera, as well as the computer, due to its outstanding characteristics.
A magnetic disk used in the HDD has a plurality of data tracks formed concentrically. Each data track has a plurality of data sectors recorded thereon. Further, a plurality of servo data are recorded discretely in a circumferential direction on the magnetic disk. A head element portion supported by a swinging actuator accesses a desired data sector in accordance with address information of servo data, which allows data write to and data retrieval from a data sector.
The HDD repeats data write and data retrieval operations on a recording surface of the magnetic disk. In writing data to a selected track, leakage fields from a head affect the magnetic data on tracks adjacent to the selected track. Repetitive changes in magnetization on the data track affect magnetization of adjacent tracks. Therefore, if writing data on a certain data track is repeated, interference to the adjacent tracks due to the leakage fields from the head and the changes in magnetization on the data track is repeated so that the user data on the adjacent data tracks may change to cause a read hard error.
In order to prevent such a read hard error, a technique has been proposed that counts the number of write operations to each data track and rewrites data of adjacent data tracks if the number of write operations exceeds a threshold (for example, refer to Japanese Patent Publication No. 2005-216476 “Patent Document 1”). Specifically, the HDD disclosed in Patent Document 1 counts the number of write operations to the adjacent data tracks with respect to each data track. If the number of writing to the adjacent data track exceeds the threshold, the HDD retrieves the data on the particular data track and rewrites the retrieved data onto the same data track.
The above-described conventional technique effectively prevents occurrence of a read hard error due to repetitive data write onto a certain data track. However, as the number of the data tracks of the magnetic disk increases, the memory area required for recording the number of write operations increases. Although the storage capacity of the HDD notably increases, it is required to decrease the memory area for recording the number of write operations. Besides, it is supposed that the influence of data write expands to a wider area than the adjacent data tracks with decrease in track pitch.