An apparatus having a memory and a controller is disclosed. The memory may have a write head and sectors in tracks. The controller may have a sector map and a translation map and may be configured to (i) receive a write command having a logical block address and a range value, (ii) examine the sector map to find a sector sequence (a) marked free, (b) about to reach the write head and (c) at least as long as the range value, (iii) write new data in the sector sequence, (iv) update the translation map to associate the logical block address of the write command with a physical address of the written sectors and (v) update the sector map according to the sectors written. Each entry in the sector map generally corresponds to a respective sector and indicates whether the respective sector contains valid data or is free.

The disclosure is related to systems and methods of On the Fly Formatting. Various parameters that influence areal density of hard disc regions can be changed on the fly based on storage capacity and reliability needs. Further adjustments can be made to the formatting of the region to fine tune achievable storage capacity and reliability values. In some cases, the formatting can include error correction code strength, gap widths between user data sectors and servo data sectors, other characteristics or parameters, or any combinations thereof.

According to one embodiment, a magnetic disk device includes a disk including a first sector arranged at a first radial position deviated from a target position in a radial direction by a first offset amount larger than a first threshold value, a head that writes data to the disk and reads data from the disk, and a controller that reads the first sector by arranging the head at a second radial position deviated from the target position by a second offset amount different from the first offset amount.

A data storage device is disclosed comprising a head actuated over a magnetic media. A write boost is configured to a first setting, and a first pattern of magnetic transitions is written to a first servo field of a servo sector on the magnetic media using the first setting for the write boost. The write boost is configured to a second setting different from the first setting, and the first pattern of magnetic transitions is written to a second servo field of the servo sector on the magnetic media using the second setting for the write boost.

According to one embodiment, a magnetic disk device includes a disk including a first sector arranged at a first radial position deviated from a target position in a radial direction by a first offset amount larger than a first threshold value, a head that writes data to the disk and reads data from the disk, and a controller that reads the first sector by arranging the head at a second radial position deviated from the target position by a second offset amount different from the first offset amount.

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.

A method for storing data in groups of logical data sectors across a plurality of contiguous data tracks of a data storage medium includes defining a plurality of interleaver patterns, each interleaver pattern including a sector interleaving pattern specifying a respective order in which segments of respective ones of the logical data sectors are spread across physical data sectors of a respective one of the contiguous data tracks. For each respective group of logical data sectors, a respective interleaver pattern is selected. Data is written from each group of logical data sectors to one of the data tracks using the selected interleaver pattern. Each respective group of logical data sectors is written to its respective data track using a different interleaver pattern from any other group of logical data sectors written to an adjacent data track, so that no two adjacent data tracks are written using the same interleaver pattern.

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 magnetic disk, a read head for reading data from sectors and tracks of the magnetic disk, a read channel including a first circuit configured to process an output signal from the read head according to a value of a parameter, and processor. The processor is configured to, upon detection of a read error while the read head is reading data from an error sector of an error track, determine an error amount in each sector in the error track, select from the error track a plurality of sectors having an error amount that is within a predetermined range from an error amount of the error sector, perform a training read on the selected sectors, determine a new value of the parameter based on the training read, and set the new value of the parameter for the read channel.

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.