According to an embodiment, a magnetic disk is provided with a track, and the track is provided with a data sector. The data sector includes a plurality of servo regions in which servo data is written, and a plurality of first data regions. Each of the plurality of first data regions is disposed between two servo regions of the plurality of servo regions. The controller executes a first write operation of writing data sequentially to the plurality of first data regions using the magnetic head. After the first write operation, the controller executes a second write operation of retrying the writing to a second data region in which the write error is detected among the plurality of first data regions, and not retrying the writing to a third data region in which the write error is not detected among the plurality of first data regions.

A method of recovering data from one or more failed data sectors includes estimating a reader offset position from a first or a second read attempt of the one or more failed data sectors at a current set of channel parameters and basing the estimated reader offset position on, at least in part, a position error signal generated during the first or second read attempt. At least one read is performed on the one or more failed data sectors at the estimated reader offset position to obtain one or more samples. The one or more samples are processed to obtain a processed sample. Iterative outer code recovery is performed on the processed sample.

A method for writing repeatable run-out data, representing a recurring contribution to position error, to a rotating constant-density magnetic storage medium, includes repeating, for each respective track at a respective radius of the constant-density magnetic storage medium, (1) determining a respective track pattern frequency based on track location and desired data density, (2) locating a position in a respective servo wedge on the respective track based on servo sync mark detection, (3) writing the repeatable run-out data to the respective servo wedge at a time delay, from the location of the position in the respective servo wedge, that is inversely proportional to the respective radius, to achieve a predetermined offset, and (4) repeating the determining, the locating and the writing for each servo wedge on the respective track of the constant-density magnetic storage medium.

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of data tracks, wherein each servo sector comprises a track ID followed by a sync mark followed by at least one servo burst, and a first servo sector does not include a preamble. During a read operation, a servo gate is opened in order to read the track ID, the sync mark, and the servo burst of the first servo sector. During a write operation, the servo gate is opened in order to miss reading at least part of the track ID of the first servo sector so as to reduce a write gap preceding the first servo sector.

Identifying recording disk defects in a data storage device such as a hard disk drive (HDD), for which disk defects are not previously identified, includes responsive to a first user data write request to a particular storage area of a disk medium, writing the user data to the particular storage area, reading the written user data from the particular storage area, and verifying the integrity of the user data read from the particular storage area. Upon passing, a second user data write request to the same particular storage area can be fulfilled without again reading and verifying. Upon failing, the particular storage area is marked as defective and the user data is written to a different storage area. This procedure can be repeated in response to each initial user write request to each storage area of each disk medium, foregoing the need for disk surface scanning during manufacturing.

According to one embodiment, a control device to be used for a magnetic disk device includes a power source control section and a control section. The power source control section configured to change an output voltage value of a voltage supplied to the control device from a power source on the basis of a voltage control parameter. The control section configured to, when a magnetic head makes access to a zone set on a magnetic disk, set a voltage control parameter provided in such a manner as to be correspondent to the zone to the power source control section.

A hard disk drive includes a base deck, a cover coupled to the base deck to create an internal cavity, and a testing assembly coupled to the cover. The testing assembly includes a housing and is arranged to expose an organic material, for example grease or oil, to the internal cavity.

A hard disk drive includes a base deck, a cover coupled to the base deck to create an internal cavity, and a testing assembly coupled to the cover. The testing assembly includes a housing and is arranged to expose an organic material, for example grease or oil, to the internal cavity.

According to one embodiment, a magnetic disk device includes a magnetic disk, a first magnetic head and a second magnetic head that are moved independently of each other, a first controller chip, a second controller chip, and a third memory. The first controller chip includes a first processor and a first memory, and controls the first magnetic head. The second controller chip includes a second processor and a second memory, and controls the second magnetic head. Management information is stored in the third memory. The first controller chip is connected to the third memory. The second controller chip is connected to the third memory via the first controller chip. The second controller chip saves the management information into the second memory.

A read error occurs when performing a read with a first read head. It is determined whether a second read head capable of use in a read-while-write operation runs within or outside of a first track. The second read head width defines a verified area on a track. If the second read head runs entirely within the first track, the first read head is positioned within the verified area. If the second read head runs partly outside of the first track, and a portion of the verified area within the first track is wider than the width of the first read head, the first read head is positioned within the portion of the verified area that is within the first track. If the portion is not wider, the first read head is positioned so that a side of the first read head is at a border the first track.