A disk device includes a disk medium, a magnetic recording head, a processor configured to control the magnetic recording head to write data to and read data from a plurality of tracks of the disk medium on a sector-by-sector basis, and a check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track. The processor controls the magnetic recording head to write check value data for a first track of the plurality of tracks in a first sector on the disk medium and check value data for a second track of the plurality of tracks in a second sector on the disk medium that is adjacent to the first sector.

Systems and methods are disclosed for error recovery in a digital data channel. In an error recovery approach when the hardware fails to recover a sector, the sample for that sector can be saved along with a metric measure that indicates the quality of the sample. This process can begin from a first on-the-fly receiving and decoding of data. During each step of error recovery, a retry attempt may either use samples obtained during a new decoding attempt or may use a sample, or a combination of samples, having the best metric from an earlier attempt, or a combination of earlier attempts, to perform the recovery during a current retry recovery attempt.

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.

Methods and systems for detecting hidden sectors in a hard drive. The method may include initiating a linear copy of the hard drive and, while the hard drive is being copied, capturing images of a platter and an actuator arm within the hard drive using an imaging device. The captured images are output and they indicate a range of movement of the actuator arm across the platter during the linear copy. Ranges of movement that fail to scan across the full expected size of the platter may be indicative of a modified partition record that maliciously hides a portion of the hard drive from the copy operation.

Methods, apparatuses and systems for detecting defective sectors on a recording medium. A defective sector detector apparatus comprises an error-corrected ECC symbol number calculator and a defective sector determination unit. The error-corrected ECC symbol number calculator is configured to count a total number of error correcting code (ECC) symbols that are error-corrected in data read from data sectors on a track of a recording medium of the storage device. The defective sector determination unit is configured to receive the total number of ECC symbols that are error-corrected for a data sector from the error-corrected ECC symbol number calculator and determine whether the total number of ECC symbols that are error-corrected exceeds a threshold value. If it is determined that the total number of ECC symbols that are error-corrected exceeds the threshold value, the defective sector determination unit outputs information indicating the data sector to be a defective sector.

A disk device includes a disk medium, a magnetic recording head, a processor configured to control the magnetic recording head to write data to and read data from a plurality of tracks of the disk medium on a sector-by-sector basis, and a check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track. The processor controls the magnetic recording head to write check value data for a first track of the plurality of tracks in a first sector on the disk medium and check value data for a second track of the plurality of tracks in a second sector on the disk medium that is adjacent to the first sector.

When a shingled magnetic recording (SMR) hard disk drive (HDD) receives a write command that references one or more target logical block addresses (LBAs) and determines that one or more target LBAs are included in a range of LBAs for which data are stored in a memory of the drive, additional data are written to the media cache of the SMR HDD along with the write data during the same disk access. The additional data include data that are stored in the volatile memory and are associated with one or more LBAs that are adjacent in LBA space to the target LBAs. The one or more LBAs that are adjacent in LBA space to the target LBAs may include a first group of LBAs that is adjacent to and follows the target LBAs and a second group of LBA that is adjacent to and precedes the target LBAs.

A magnetic disk device includes a disk including a plurality of error sectors including a defect, a first track having a first parity sector, and a controller. The controller is configured to, upon receiving a write command to write first data in a first region of a portion of the first track, which is a portion of the first track, first perform an XOR operation on all sectors of the first track other than one or more sectors of the first region and the first parity sector of the first track, and then write the first data in the one or more sectors of the first region, perform a second XOR operation on the one or more sectors of the first region and the result of the first XOR operation, and write the result of the second XOR operation in the first parity sector.

According to the embodiment, an HDC receives a plurality of data segments from a host, and executes generation and addition of a first code and output of a data segment to which the first code is added to each data segment. An HDC calculates exclusive OR with respect to the first codes, and outputs obtained first information. The RWC performs data conversion and calculation of exclusive OR on the plurality of data segments to which the first code is added, and outputs the plurality of data segments after the data conversion and a track parity obtained by the calculation of the exclusive OR. The RWC acquires the first code from the plurality of data segments. The RWC calculates exclusive OR with respect to a group of the second codes which are the acquired first codes to acquire second information. The RWC compares the first information with the second information.

A heat-assisted magnetic recording head is moved relative to a magnetic recording medium. The medium comprises a plurality of sectors. The sectors define a plurality of sector groups distributed around a circumference of the medium. The sectors of each sector group are written using different operational currents supplied to a laser diode of the head such that at least one sector from each sector group is written using one of the different operational currents. For each of the different operational currents, an average write performance metric is calculated for all sectors written at each of the different operational currents. A particular operational current of the different operational currents is determined that results in a best average write performance metric.