A method includes determining an error after attempting to read, via a first read transducer and a second read transducer, a data sector in a first data track. The method further includes calculating a weight ratio associated with the data sector and determining a read offset direction of the data sector based, at least in part, on the calculated weight ratio.

A hard disk drive includes a magnetic recording medium comprising data sectors along a data track, a read head arranged to read data from the data sectors, and an integrated circuit. The integrated circuit includes circuitry programmed to detect a read error associated with a first of the data sectors and continue to read data from the data sectors after the detection of the read error.

A method for writing servo information in a disk drive that includes a write head and one or more recording surfaces includes: writing a first portion of a first spiral with the write head on a first recording surface of the one or more recording surfaces while controlling a radial position of the write head with a controller that is configured with a first set of controller parameter values; after the read head crosses a second spiral formed on a second recording surface of the one or more recording surfaces, determining a radial position error for the write head based on information associated with the second spiral; and in response to the radial position error exceeding a disturbance threshold value, writing a second portion of the first spiral with the write head while controlling the radial position of the write head with the controller while the controller is configured with a second set of controller parameter values.

Processing hard disk drive (HDD) data track repeatable runout (RRO) compensation data includes, for each read-write head constituent to the HDD, and for each data track on which the read-write head operates, saving RRO compensation data to single-level cell (SLC) area of a NAND memory component, and finalizing the RRO data before processing the next read-write head of the HDD, thereby minimizing the SLC area used. Finalizing the RRO data may include sorting the RRO data for the read-write head in the SLC area, moving the sorted RRO data from the SLC area to triple-level cell (TLC) or other higher-level cell area of the NAND, and then erasing the RRO data from the SLC area to free up that memory space, thereby reducing the risk of wearing out the TLC area.

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.

The presently disclosed technology teaches integrating disc drive electronics into a transducer head. Decreased electrical transit times and data processing times can be achieved by placing the electronics on or within the transducer head because electrical connections may be made physically shorter than in conventional systems. The electronics may include one or more of a control system circuit, a write driver, and/or a data buffer. The control system circuit generates a modified clock signal that has a fixed relation to phase and frequency of a bit-detected reference signal that corresponds to positions of patterned bits on the disc. The write driver writes outgoing data bits received from an external connection to off-head electronics directly to the writer synchronized with the modified clock signal. The data buffer stores and converts digital data bits sent from the off-head electronics to an analog signal that is synchronized with the modified clock signal.

A set of consecutive user data wedges are each located between consecutive servo wedges of a heat-assisted recording medium. Test data is written at least every other one of the consecutive data wedges using different laser power values. Based on reading the test data, a nominal laser power is selected for use by the read/write head.

The technology disclosed herein pertains to a system and method for managing off-track retry. An implementation of a method of determining offset direction for read off-track retry includes storing analog to digital converter (ADC) values of data read from a data sector by a data reader in a read channel buffer, calculating an indicator value of the distribution of the ADC values, determining an amount of offset for the data reader based on the indicator value, and moving the data reader by the amount of offset before performing a read retry operation.

The technology disclosed herein pertains to a system and method for managing off-track retry. An implementation of a method of determining offset direction for read off-track retry includes storing analog to digital converter (ADC) values of data read from a data sector by a data reader in a read channel buffer, calculating an indicator value of the distribution of the ADC values, determining an amount of offset for the data reader based on the indicator value, and moving the data reader by the amount of offset before performing a read retry operation.

In an optical disc apparatus for reproducing information recorded on a track of an optical disc, an optical head irradiates a light beam onto the track, detects a reflected light reflected by the track, and generates a reproduction signal based on the reflected light. A decoder circuit decodes the reproduction signal, and generates a decoded signal including information recorded on the track. A correlation detector circuit calculates a cross-correlation value between the reproduction signal and the decoded signal. A servo circuit detects a deviation amount of an irradiation position of the light beam onto the track, from the reproduction signal, and controls the irradiation position of the optical head based on the cross-correlation value and the deviation amount.