Abstract: Embodiments of the present invention provide a magnetic disk drive in which the error correction capability of ECC is improved without sacrificing the storage capacity. In one embodiment, a data track adopts a format structure in which no data-to-data gap area is formed in data sectors. When one of the data sectors is updated in a state in which the rotational speed of a magnetic disk does not satisfy specified conditions, a leading end area of a succeeding data sector or a trailing end area of a preceding data sector is overwritten by the data sector. If a read error occurs in the overwritten data sector, ERP steps are executed to perform read retry so that the read error is recovered by means of on-the-fly ECC or erasure correction. In the case of the erasure correction, an erasure pointer equivalent to the maximum number of overwritten bytes is set.

Abstract: Embodiments of the invention provide a magnetic disk drive capable of reducing an area used for a preamble of each data sector to increase the storage capacity. The magnetic disk drive adopts a data-surface servo system. In one embodiment, main preambles are written on a magnetic disk at a frequency of a data clock. Each of data sectors is written with a write clock that is synchronized with a signal obtained by reading the main preamble. The data sectors include sub preambles respectively. When the data sector which has been written in this manner is read, a read clock is synchronized by use of a signal obtained by reading the main preamble, and a signal obtained by reading the sub preamble included in a data sector to be read. The bit length of the sub preamble is shorter than that of the conventional preamble that is used to independently achieve the synchronization.

Abstract: Embodiments of the invention detect a head offset in a data region between servo regions in a data write operation. To detect a head offset even in a data region between servo regions, a magnetic disk drive according to an embodiment of the invention makes adjustments to maintain a fixed relative position between the write head and the read head and reads positional information embedded in certain data by use of the read head until just before writing data. This allows the magnetic disk drive to detect a head offset until just before writing data, leading to enhanced reliability.

Abstract: Embodiments of the invention provide a magnetic disk drive capable of reducing an area used for a preamble of each data sector to increase the storage capacity. The magnetic disk drive adopts a data-surface servo system. In one embodiment, main preambles are written on a magnetic disk at a frequency of a data clock. Each of data sectors is written with a write clock that is synchronized with a signal obtained by reading the main preamble. The data sectors include sub preambles respectively. When the data sector which has been written in this manner is read, a read clock is synchronized by use of a signal obtained by reading the main preamble, and a signal obtained by reading the sub preamble included in a data sector to be read. The bit length of the sub preamble is shorter than that of the conventional preamble that is used to independently achieve the synchronization.

Abstract: Embodiments of the present invention provide a magnetic disk drive in which the error correction capability of ECC is improved without sacrificing the storage capacity. In one embodiment, a data track adopts a format structure in which no data-to-data gap area is formed in data sectors. When one of the data sectors is updated in a state in which the rotational speed of a magnetic disk does not satisfy specified conditions, a leading end area of a succeeding data sector or a trailing end area of a preceding data sector is overwritten by the data sector. If a read error occurs in the overwritten data sector, ERP steps are executed to perform read retry so that the read error is recovered by means of on-the-fly ECC or erasure correction. In the case of the erasure correction, an erasure pointer equivalent to the maximum number of overwritten bytes is set.

Abstract: Embodiments of the invention detect a head offset in a data region between servo regions in a data write operation. To detect a head offset even in a data region between servo regions, a magnetic disk drive according to an embodiment of the invention makes adjustments to maintain a fixed relative position between the write head and the read head and reads positional information embedded in certain data by use of the read head until just before writing data. This allows the magnetic disk drive to detect a head offset until just before writing data, leading to enhanced reliability.