A storage device includes a controller that determines a degree of data degradation for a data track targeted by a pending read command and sets a head/media clearance parameter for execution of the read command based on the determined degree of data degradation for the data track, the head/media clearance parameter providing for a greater head-media separation when the determined level of degradation is lower than when the determined level of degradation is higher.

A method for writing data onto a medium on which data are stored in tracks includes encoding the data into at least one codeword, and writing a respective portion of each of the at least one codeword onto respective different tracks on the medium. The writing may include writing a respective portion of each of the at least one codeword onto respective different adjacent tracks on the medium. Another method for reading data includes positioning a plurality of read heads to read codewords that have been written across multiple tracks of a medium. Each read head in the plurality of read heads reads a different portion of the first group of the multiple tracks, and where each different portion of the multiple tracks overlaps at least one other different portion of the multiple tracks. Signals are detected from the plurality of read heads, and the detected signals are decoded.

In an optical disc apparatus that records and reproduces data onto and from an optical disc in units of predetermined block, an information divider divides the data so as to reduce an amount of the data included in each of blocks when a recording state of the optical disc does not satisfy a predetermined criterion, and reproduces recording data in units of the block by adding sub-information including a value indicating the amount of the data included in each of the blocks. An error-correction encoder circuit encodes the recording data in a first error-correction code format, and a recorder converts encoded recording data into a recording signal, and records the recording signal onto the optical disc. A quality evaluator circuit produces an evaluation value indicating a recording quality based on a result of reproducing the recording signal recorded on the optical disc.

The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

A storage device includes a controller that determines a degree of data degradation for a data track targeted by a pending read command and sets a head/media clearance parameter for execution of the read command based on the determined degree of data degradation for the data track, the head/media clearance parameter providing for a greater head-media separation when the determined level of degradation is lower than when the determined level of degradation is higher.

The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

A data storage device is disclosed comprising a head actuated over a disk. A first plurality of codewords and corresponding parity sector are generated, and a second plurality of codewords and corresponding parity sector are generated. The first and second plurality of codewords are written to the disk, and during a read of the first and second set of codewords, M codeword locations within the data track that are unrecoverable are saved, and N codeword locations out of the M codeword locations are selected based on a quality metric of the read. The N codewords are reread from the data track at the N codeword locations and reliability metrics associated with the N codewords are saved. The saved reliability metrics are updated using at least one of the first parity sector or the second parity sector.

A data storage device is disclosed comprising a head actuated over a disk. A first plurality of codewords and corresponding parity sector are generated, and a second plurality of codewords and corresponding parity sector are generated. The first and second plurality of codewords are written to the disk, and during a read of the first and second set of codewords, M codeword locations within the data track that are unrecoverable are saved, and N codeword locations out of the M codeword locations are selected based on a quality metric of the read. The N codewords are reread from the data track at the N codeword locations and reliability metrics associated with the N codewords are saved. The saved reliability metrics are updated using at least one of the first parity sector or the second parity sector.

In an optical disc apparatus that records and reproduces data onto and from an optical disc in units of predetermined block, an information divider divides the data so as to reduce an amount of the data included in each of blocks when a recording state of the optical disc does not satisfy a predetermined criterion, and reproduces recording data in units of the block by adding sub-information including a value indicating the amount of the data included in each of the blocks. An error-correction encoder circuit encodes the recording data in a first error-correction code format, and a recorder converts encoded recording data into a recording signal, and records the recording signal onto the optical disc. A quality evaluator circuit produces an evaluation value indicating a recording quality based on a result of reproducing the recording signal recorded on the optical disc.

To obtain a signal quality evaluation value capable of having a high correlation to an error rate and high accuracy for a reproduction signal of high density recording. For the object, an estimated value of a path selection error rate is obtained on the basis of a distribution of a path metric difference between a maximum likelihood path at each time, which is a detection path in maximum likelihood decoding in a PRML decoding system and a second path having a second highest likelihood. Further, an average error bit number in erroneous detection is obtained from a bit difference number between the maximum likelihood path and the second path at the time of path selection of each time in the maximum likelihood decoding. In addition, an estimated bit error rate is obtained from results and an evaluation value according to the estimated bit error rate is generated.