According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, an electric power supply section, a control section, and an address storage section. The control section reads data from the magnetic disk by means of the read head on the basis of the address stored in the address storage section at predetermined timing, and writes the read data to the magnetic disk by means of the write head without suppressing the magnetic field range.

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, an electric power supply section, a control section, and an address storage section. The control section reads data from the magnetic disk by means of the read head on the basis of the address stored in the address storage section at predetermined timing, and writes the read data to the magnetic disk by means of the write head without suppressing the magnetic field range.

According to one embodiment, a magnetic disk device, including a disk, a head to write data to the disk and read data from the disk, a preamplifier to generate a recording current corresponding to data that the head writes to the disk, and a controller to convert a first data pattern in first write data, in accordance with a pattern length of a second data pattern previous to the first data pattern, to a different data pattern including a pseudo polarity inversion that does not cause a polarity inversion when converting the first data pattern to the recording current.

According to one embodiment, a magnetic disk device, including a disk, a head to write data to the disk and read data from the disk, a preamplifier to generate a recording current corresponding to data that the head writes to the disk, and a controller to convert a first data pattern in first write data, in accordance with a pattern length of a second data pattern previous to the first data pattern, to a different data pattern including a pseudo polarity inversion that does not cause a polarity inversion when converting the first data pattern to the recording current.

Processing hard disk drive (HDD) data track repeatable runout (RRO) compensation data includes, for each read-write head constituent to the HDD, and for each data track on which the read-write head operates, saving RRO compensation data to single-level cell (SLC) area of a NAND memory component, and finalizing the RRO data before processing the next read-write head of the HDD, thereby minimizing the SLC area used. Finalizing the RRO data may include sorting the RRO data for the read-write head in the SLC area, moving the sorted RRO data from the SLC area to triple-level cell (TLC) or other higher-level cell area of the NAND, and then erasing the RRO data from the SLC area to free up that memory space, thereby reducing the risk of wearing out the TLC area.

Processing hard disk drive (HDD) data track repeatable runout (RRO) compensation data includes, for each read-write head constituent to the HDD, and for each data track on which the read-write head operates, saving RRO compensation data to single-level cell (SLC) area of a NAND memory component, and finalizing the RRO data before processing the next read-write head of the HDD, thereby minimizing the SLC area used. Finalizing the RRO data may include sorting the RRO data for the read-write head in the SLC area, moving the sorted RRO data from the SLC area to triple-level cell (TLC) or other higher-level cell area of the NAND, and then erasing the RRO data from the SLC area to free up that memory space, thereby reducing the risk of wearing out the TLC area.

Example systems, data storage devices, and methods to provide data protection during concurrent operations for multiple actuator data storage devices are described. The data storage device includes a plurality of actuators configured to actuate a plurality of heads over different subsets of a plurality of disk surfaces. Responsive to receiving a write command for one of the actuators, the coupling state with at least one other of the actuators is determined and execution of write commands is inhibited if the coupling state indicates a possible coupling event. The inhibit of the write commands in the presence of coupling events may prevent off-track writes and protect data.

Example systems, data storage devices, and methods to provide data protection during concurrent operations for multiple actuator data storage devices are described. The data storage device includes a plurality of actuators configured to actuate a plurality of heads over different subsets of a plurality of disk surfaces. Responsive to receiving a write command for one of the actuators, the coupling state with at least one other of the actuators is determined and execution of write commands is inhibited if the coupling state indicates a possible coupling event. The inhibit of the write commands in the presence of coupling events may prevent off-track writes and protect data.

A heat-assisted magnetic recording device is disposed in a hermetically sealed enclosure. The device includes a slider comprising a reader, a writer, and an optical waveguide configured to couple light from a light source to a near-field transducer situated at or near an air bearing surface of the slider. The near-field transducer comprises an enlarged portion and a peg extending from the enlarged portion in a direction of the air bearing surface. A fill gas is provided within the enclosure. The fill gas comprises a mixture of a low-density, inert gas and at least one gas that oxidizes carbon, where the total carbon oxidizing gas concentration of the fill gas is 3-50% by volume. In certain embodiments, the fill gas comprises a hydrogen concentration sufficient to retard oxidation of the peg when the peg is at an operating temperature associated with write operations.

A heat-assisted magnetic recording device is disposed in a hermetically sealed enclosure. The device includes a slider comprising a reader, a writer, and an optical waveguide configured to couple light from a light source to a near-field transducer situated at or near an air bearing surface of the slider. The near-field transducer comprises an enlarged portion and a peg extending from the enlarged portion in a direction of the air bearing surface. A fill gas is provided within the enclosure. The fill gas comprises a mixture of a low-density, inert gas and at least one gas that oxidizes carbon, where the total carbon oxidizing gas concentration of the fill gas is 3-50% by volume. In certain embodiments, the fill gas comprises a hydrogen concentration sufficient to retard oxidation of the peg when the peg is at an operating temperature associated with write operations.