According to one embodiment, a magnetic disk device includes: a disk; a head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a gap, a first assist element that is disposed in the gap and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction; and a controller configured to: cause a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk; and cause a second assist energy from the second assist element to be applied to the disk and affect a coercive force of the disk, wherein the first assist energy is different from the second assist energy.

A data storage device is disclosed comprising a head actuated over an energy assisted magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A write operation to a first data sector is executed by applying a first current to a write coil of the head while the head is over a second data sector preceding the first data sector, wherein the first current comprises a first amplitude. A second current is applied to the write coil while the head is over the first data sector, wherein the second current comprises a second amplitude lower than the first amplitude.

According to one embodiment, a magnetic disk apparatus is provided with a magnetic disk, a buffer memory, and a control circuit. The magnetic disk has plural bands, each of which is a storage area in which data is written by the method of SMR. The control circuit receives a read request from outside. If the data requested to be read is first data of an update target stored in a first band among plural bands, the control circuit reads the first data from the first band, stores the first data in a buffer memory, and updates the first data in the buffer memory. Then, the control circuit transmits the first data in the buffer memory to the outside and writes the first data in the buffer memory to one of the plural bands.

A data storage device is disclosed comprising a head actuated over an energy assisted magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A write operation to a first data sector is executed by applying a first current to a write coil of the head while the head is over a second data sector preceding the first data sector, wherein the first current comprises a first amplitude. A second current is applied to the write coil while the head is over the first data sector, wherein the second current comprises a second amplitude lower than the first amplitude.

A write signal may be adjusted, or modified, based on one or more read signals acquired, or read from, one or more portions proximate a target portion on a storage medium where the write signal is to be applied. The one or more read signals may be read from the storage medium in response to receiving a write data unit such that the read signals may not need to be buffered or later clock synchronized to the write signal.

A thermally-assisted magnetic recording head includes a main pole and a plasmon generator. The plasmon generator includes a first material portion and a second material portion formed of different materials. The first material portion is located away from the medium facing surface. The second material portion includes a near-field light generating surface. The main pole has a front end face including a first end face portion and a second end face portion. The near-field light generating surface, the first end face portion and the second end face portion are arranged in this order along the direction of travel of a recording medium.

A disk drive apparatus determines a pattern of bits of a data signal applied to a magnetic write transducer of a heat-assisted magnetic recording apparatus. The magnetic write transducer applies a magnetic field to a recording medium in response to the data signal. A laser power signal is applied to a laser that heats the recording medium while the magnetic field is applied. The laser power signal is modulated based on the pattern of bits. The modulation reduces differences between track widths of recorded marks having different elapsed time values and/or increases a signal-to-noise ratio of the recorded marks having different elapsed time values.

A recording device including at least one processor, wherein the processor is configured to: acquire, for attached information attached to each of a plurality of recording target data recorded on a recording medium, a first relevance degree according to a frequency at which data other than the recording target data attached with information having the same contents as the attached information is read out within a period determined in advance; derive, for each combination of a plurality of recording target data, a second relevance degree representing a possibility that the plurality of recording target data included in the combination is read out within the period based on the first relevance degree; and classify the plurality of recording target data into groups based on the second relevance degree and perform control of recording the classified data on the recording medium for each group.

According to one embodiment, a magnetic disk device includes: a disk; a head including a main magnetic pole, a write shield that faces the main magnetic pole in a first direction and is separated from the main magnetic pole by a gap, a first assist element that is disposed in the gap and a second assist element that is disposed in the gap and is positioned relative to the first assist element in a second direction intersecting the first direction; and a controller configured to: cause a first assist energy from the first assist element to be applied to the disk and affect a coercive force of the disk; and cause a second assist energy from the second assist element to be applied to the disk and affect a coercive force of the disk, wherein the first assist energy is different from the second assist energy.

A data storage device is disclosed comprising a head actuated over an energy assisted magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A write operation to a first data sector is executed by applying a first current to a write coil of the head while the head is over a second data sector preceding the first data sector, wherein the first current comprises a first amplitude. A second current is applied to the write coil while the head is over the first data sector, wherein the second current comprises a second amplitude lower than the first amplitude.