According to one embodiment, a controller of a magnetic disk device determines whether or not to cause a magnetic flux control unit to generate a magnetic field, and in accordance with the determination result, causes a control circuit to apply a drive voltage to the magnetic flux control unit so that an assisted recording area and a non-assisted recording area are provided in a magnetic disk mixedly as desired.

A system is provided to receive a first request to write data to an HDD which comprises a plurality of platters with corresponding heads, wherein a respective platter includes a plurality of tracks. The system aligns the heads at a same first position on a first track of each platter, and distributes the data as a plurality of data sectors to track sectors located at the same first position on the first track of each platter. The system then receives a second request to read the data from the HDD, and aligns the heads at a same random position on the first track of each platter. Subsequently, the system reads, during a single rotation of the platters, all data stored on the first track of each platter, stores the read data in a data buffer, and reshuffles the read data in the data buffer to obtain the requested data.

In a disk drive, when an off-track error occurs during a sequential disk access operation that spans multiple contiguous data tracks, efficient recovery is performed. In an embodiment, the disk access operation (e.g., reading from or writing to a disk) is attempted for all sectors of the sequential disk access operation. The disk access operation is then attempted again for sectors associated with any off-track errors that occurred during the disk access operation. In another embodiment, when an off-track error occurs during a sequential write operation in a shingled magnetic recording drive, the data originally targeted to be written to a first portion is written to a second portion of the data track that follows the first portion. Since no additional revolutions of the disk are needed for data associated with the sequential write operation to be written to the disk.

Systems and methods are disclosed for reducing adjacent track erasure from write retry operations. In certain embodiments, an apparatus may comprise a circuit configured to abort a write operation while writing to a selected sector of a disc storage medium during a first revolution of the disc storage medium, and mark the selected sector as a temporary bad sector in a mapping table. The circuit may perform a write retry to continue the write operation starting at a next sector contiguously following the selected sector, without attempting to write the selected sector again, during a second revolution of the magnetic disc.

A magnetic disk device includes a magnetic disk, which includes, in a track, a plurality of first sectors each recording user data and a second sector recording parity data for restoring the user data recorded in the first sectors, and a disk controller configured to read data from a plurality of sectors including the first sectors and the second sector based on an instruction from a host, and to detect whether there is an error in each of the first sectors when the user data is read from the first sectors. The disk controller continues reading the data recorded in the plurality of sectors even when an error is detected in one of the first sectors by the disk controller.

Systems for location selection based on adjacent location errors are provided. One system includes a monitor module that monitors write numbers for one or more locations on a storage device, wherein a write number in the write numbers describes a number of times a storage device operation has been performed at a location in the one or more locations. Additionally, the system includes an identification module that identifies locations in one or more locations that are susceptible to adjacent location errors, wherein an adjacent location error is an error caused by a storage device operation associated with an adjacent location. Also, the system includes a selection module that selects a location in one or more locations for storing data based on monitored write numbers and identified locations.

A setting unit is configured to set first write processing for writing second data in a hard disk, or second write processing for writing the second data in the hard disk and reading data that is written by writing of the second data, and a change unit is configured to change the write processing set in the setting unit. The change unit changes the write processing set in the setting unit from the first write processing to the second write processing, based on determination that the first data is greater than or equal to a threshold by a determination unit.

A method includes monitoring operations performed on tracks in a main storage area of a disc, and identifying a track of the tracks in the main storage area susceptible to adjacent track interference (ATI). When a track is identified, the identified track or an adjacent track which contributes to ATI of the identified track is remapped to an ATI safe zone of the disc having a tracks per inch (TPI) density lower than a TPI density of the main storage area.

Techniques perform data access to a disk array. The disk array includes a parity disk and a plurality of data disks. Via such techniques, data is written to the parity disk in the disk array in response to a write request to a failed data disk in the disk array when the disk array is in a degraded state; and corresponding degraded storage position information is set in disk resource mapping information so as to indicate that the data are stored in the parity disk. Accordingly, enormous computing resources can be saved, and I/O operations required by reads in the degraded state can be reduced.

In a disk drive, when an off-track error occurs during a sequential disk access operation that spans multiple contiguous data tracks, efficient recovery is performed. In an embodiment, the disk access operation (e.g., reading from or writing to a disk) is attempted for all sectors of the sequential disk access operation. The disk access operation is then attempted again for sectors associated with any off-track errors that occurred during the disk access operation. In another embodiment, when an off-track error occurs during a sequential write operation in a shingled magnetic recording drive, the data originally targeted to be written to a first portion is written to a second portion of the data track that follows the first portion. Since no additional revolutions of the disk are needed for data associated with the sequential write operation to be written to the disk.