Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Nobuhiro Maeto

Kohsuke Harada

Takeyori Hara

Akihiro Yamazaki

Naoki Tagami

Takayuki Kawabe

Yusuke Tomoda

Kazuto Kashiwagi

Tomokazu Okubo

Akihiko Takeo

Hiroshi Isokawa

Masahiro Kanamaru

According to one embodiment, a magnetic disk device includes a disk that has a track including a first servo sector and a second servo sector that is different from the first servo sector, a head that writes data to the disk and reads data from the disk, and a controller that records first signal strength record data related to a signal strength at which first target servo data that is a target of the first servo sector is read, and standardizes first signal strength data related to a signal strength at which the first target servo data is read when the first target servo data is read.

Magnetic disk device

According to one embodiment, a magnetic disk device including a disk, a head which writes data to the disk and reads data from the disk, and a controller which sets a first DOL for a first sector group and a second DOL for a second sector group to different values, the first sector group including one or more first sectors and a first parity sector, the first sectors which allow an error correction process to be performed for each track based on the first parity sector, and are continuously arranged in a circumferential direction of the disk from the first parity sector, the second sector group including one or more second sectors which allow no error correction process to be performed for each track, and are continuously arranged in the circumferential direction.

Magnetic disk device and DOL setting method

According to one embodiment, a magnetic disk device includes a disk, a head configured to write data to the disk and read the data from the disk, and a controller configured to control write processing based on a first determination value corresponding to a first shift amount defined for the excessive number of times at which the first shift amount of the head in a radial direction of the disk exceeds a first threshold value causing a read error in a second track adjacent to a first track in the radial direction at a time of the write processing of the first track of the disk, and a second threshold value changing the write processing.

Magnetic disk device with enhanced control of write processing based on a shift in drift of level (DOL)

According to one embodiment, a magnetic disk device includes a disk, a write head, and a write processing unit. The write processing unit executes first write processing of writing data to a first segment of a first data sector in a first data track. The write processing unit then executes second write processing of writing data to a first segment of a second data sector in the first data track. The write processing unit then executes third write processing of writing data to a second segment of the first data sector in a second data track.

According to an embodiment, tracks on a magnetic disk each include a long-distance sector having a length in the circumferential direction covering two or more servo sectors. A controller executes an acquisition operation to acquire one or more evaluation amounts on the basis of a track pitch in each of the two or more servo sectors included in a portion adjacent to the long-distance sector. The controller executes a protection operation to protect data of an adjacent track in a case where a total value of the one or more evaluation amounts exceeds a first threshold value.

Magnetic disk apparatus and method

According to one embodiment, a magnetic disk device includes a disk that includes a first track, a head that includes a heater, writes data to the disk, and reads data from the disk, and a controller configured to set a variation of a parameter related to a write process for the disk within one round of the first track to suppress a variation of an evaluation index corresponding to a write/read processing characteristic within one round of the first track.

Magnetic disk device and refresh threshold setting method

According to one embodiment, a magnetic disk device includes a disk, a head that writes data to the disk and reads data from the disk, and a controller that corrects a first signal into a first likelihood value by machine learning based on a correct learning signal set with a likelihood other than 1 and an incorrect learning signal set with a likelihood other than 0 and executes error correction processing based on a second likelihood value according to the first signal and the first likelihood value.

Magnetic disk device and read processing method

According to one embodiment, a magnetic disk device including a disk, a head that writes data with respect to the disk and reads data from the disk, and a controller that overwrites a second track on a first track in a radial direction of the disk, performs first alternative processing of recording a first user sector in a first region when writing of the first user sector available by a user in the first track is disabled, and performs second alternative processing different from the first alternative processing of recording a first parity sector in a second region when writing of the first parity sector acquired by an XOR operation in the first track is disabled.

Magnetic disk device and read/write processing method

According to one embodiment, a magnetic disk device includes a disk, a head, and a controller setting a rewrite threshold value for executing a rewrite process of different tracks in a first sector group including at least one first sector continuous from a first parity sector in which error correction processing in units of tracks is executable based on the first parity sector and including the first parity sector, and a second sector group including at least one second sector continuous in which the error correction processing in units of tracks is unexecutable, and rewriting the first sector group and the second sector group with different frequencies.

According to one embodiment, a magnetic disk device includes a disk, a head that writes data to the disk and reads data from the disk, and a controller that executes error correction on a first sector which is unreadable in a first track from an initial reading time of initially one-round reading the first track of the disk based on first parity data corresponding to the first track.

Magnetic disk device and error correction method

According to one embodiment, a magnetic disk device includes a disk, a head including a write head and a first read head and a second read head, and a controller that disposes the first read head at a first radial position of a first track of the disk in a radial direction to read the first track, changes a main read head which serves as a reference for positioning during a read process from the first read head to the second read head when read retrying the first track, disposes the second read head as the main read head at a second radial position different from the first radial position of the first track in the radial direction to read the first track, and changes an internal setting corresponding to the main read head to read the first track.

According to one embodiment, a magnetic disk device includes a disk, a head which writes data to the disk and reads data from the disk, and a controller which increases a first recording density of data to be written to a first sector having a first overwrite in the first sector and reduces a second recording density of data to be written to a second sector having a second overwrite different from the first overwrite, on a first track of the disk.

Magnetic disk device and method for adjusting write data

According to one embodiment, a magnetic disk device includes a disk, a head including a write head that writes data to the disk, and a first read head and a second read head that read data from the disk, and a controller that, in reading a first track of a first region of the disk, positions a middle portion of the first read head and the second read head at a first track center of the first track, and in reading a second track of a second region of the disk different from the first region, positions any one of the first read head and the second read head at a second track center of the second track.

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Yokohama, Japan

Nobuhiro Maeto