Abstract: Methods and systems consistent with the present invention provide an improved system that supervises the operation of a backup amplifier. The method comprises receiving an indication that a primary amplifier failed; determining a configuration of the primary amplifier; and configuring the backup amplifier to match the configuration of the primary amplifier.

Abstract: Methods for measuring media performance associated with adjacent track interference are provided. One such method includes iteratively writing data to a target track for each of a plurality of n frequencies, measuring a first signal amplitude and a first noise for each of the n sectors on the target track, writing an aggressor track pattern proximate the target track, measuring a second signal amplitude and a second noise for each of the n sectors on the target track, calculating a weighted sum for each of the signal amplitude measurements for each of the plurality of n frequencies, and calculating a weighted sum for each of the noise measurements for each of the plurality of n frequencies, and repeating the writing the aggressor track pattern, the measuring the second signal amplitude and the second noise, and calculating the weighted sums for preselected numbers of times.

Abstract: A method is provided according to one embodiment, which executes an optimum writing method even when overwrite is intervened between mixed read and write operations. In response to receiving an overwrite command while executing the mixed operations, which writes to a predetermined tape position, when a tape position to overwrite on is encountered before the append-written data ending position of the tape (tape EOD), the overwritten tape position is regarded as the append-written data ending position of the tape (tape EOD) to update the tape EOD by the overwritten tape position. When a tape position to overwrite is encountered after the append-written data ending position of the tape (tape EOD), the overwritten tape position is updated by the append-written data ending position of a non-volatile memory (non-volatile EOD). The updating the EODs enhances the performance of the mixed read and write operations even when an overwrite command is intervening.

Abstract: Systems and methods are included for determining a presence of an upcoming reading field during a write mode of a storage device, and initiating a read-while write (RWW) mode of the storage device in response to the sensed reading field. Initiating the RWW mode comprises warming up the reader circuitry, generating a signal in response to an end to the write operation, and activating reader bias current in response to the generated signal.

Abstract: A write driver circuit for generating a write current pulse for use by a magnetic write head includes an output stage adapted for connection with the magnetic write head and a charge storage circuit connected with the output stage. The charge storage circuit is operative in a first mode to store a prescribed charge and is operative in a second mode to transfer at least a portion of the charge stored therein to the output stage to thereby enable an output voltage level of the output stage to extend beyond a voltage supply rail of the write driver circuit. A control circuit in the write driver circuit is operative to generate at least one control signal for selectively controlling a mode of operation of the charge storage circuit.

Abstract: Disclosed is a magnetic recording/reproduction device 2 including: a recording/reproduction head 7; and a recording/reproduction head 7 for detecting a leakage magnetic field of each of the plurality of magnetic recording cells 1 so as to reproduce information, the recording/reproduction head 7 carrying out the recording on the magnetic recording medium 4 so that the magnetic recording medium 4 includes continuous recording regions that (i) satisfy Nmin?2 and that (ii) include a continuous recording region that satisfies N?n×Nmin, where N represents a number of magnetic recording cells 1 in a continuous recording region; Nmin represents a minimum value for N; and n represents a positive integer, the continuous recording regions each being a region on a reproduction track in which region magnetic recording cells 1 sharing an identical magnetization direction are sequentially arranged in a circumferential direction of the magnetic recording medium 4.

Abstract: A hard disk drive (HDD) has a high track misregistration (TMR) mode of writing data. If the position error signal (PES) from the servo positioning information exceeds a first write inhibit threshold (WI-1), writing is not inhibited but a high TMR mode of operation is enabled. In high TMR mode, prior to writing data to the target track, the data on the adjacent tracks is read and stored in a buffer. The data to be written to the target track is also stored in the buffer, and is flagged to indicate that the data needs to be written. The data is then written to the target track. However, if during writing the PES exceeds a second threshold (WI-2), then the data from the adjacent encroached track in the buffer is flagged for writing and the process repeated with the encroached track set as the target track.

Abstract: An apparatus includes a recording media including a substrate, a plurality of tracks of magnetic material on the substrate, and a non-magnetic material between the tracks; a recording head having an air bearing surface positioned adjacent to the recording media, and including a magnetic pole, an optical transducer, and a near-field transducer, wherein the near-field transducer directs electromagnetic radiation onto tracks to heat portions of the tracks and a magnetic field from the magnetic pole is used to create magnetic transitions in the heated portions of the tracks; and a plasmonic material positioned adjacent to the magnetic material to increase coupling between the electromagnetic radiation and the magnetic material.

Abstract: Methods for measuring media performance associated with adjacent track interference are provided. One such method includes iteratively writing data to a target track for each of a plurality of n frequencies, measuring a first signal amplitude and a first noise for each of the n sectors on the target track, writing an aggressor track pattern proximate the target track, measuring a second signal amplitude and a second noise for each of the n sectors on the target track, calculating a weighted sum for each of the signal amplitude measurements for each of the plurality of n frequencies, and calculating a weighted sum for each of the noise measurements for each of the plurality of n frequencies, and repeating the writing the aggressor track pattern, the measuring the second signal amplitude and the second noise, and calculating the weighted sums for preselected numbers of times.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. A bootstrap spiral track is written to the disk, wherein the bootstrap spiral track comprises a high frequency signal interrupted by sync marks. A first sync mark is written while writing a first part of the bootstrap spiral track, and a second sync mark is written while writing a second part of the bootstrap spiral track. A switch between writing the first sync mark and the second sync mark is made in response to a spindle BEMF voltage, thereby generating a sync mark seam in the bootstrap spiral track.

Abstract: Systems and methods are included for determining a presence of an upcoming reading field during a write mode of a storage device, and initiating a read-while write (RWW) mode of the storage device in response to the sensed reading field. Initiating the RWW mode comprises warming up the reader circuitry, generating a signal in response to an end to the write operation, and activating reader bias current in response to the generated signal.

Abstract: According to one embodiment, a disk storage apparatus includes a write module and a controller. The write module is configured to move a write head over a disk, and to perform the shingled write method, recording data in the first track while erasing data from a part of the second, i.e., adjacent track. The controller is configured to acquire a first head positioning error with respect to the first track and a second head positioning error with respect to the second track. If the first head positioning error exceeds an off-track threshold value, indicating that the data may no longer be maintained in the first and second tracks, the controller inhibits the data writing.

Abstract: Apparatus and method for write delay stabilization. A write driver is adapted to output bipolar write currents to write data to a memory. A preconditioning circuit is adapted to output first and second thermal preconditioning currents through the write driver to stabilize a write delay associated with the write driver to a steady-state level prior to the writing of data to the memory.

Abstract: According to one embodiment, an information recording device includes: a recording controller configured to control recording of information on a magnetic recording medium having tracks by a recording method; a managing module configured to manage two or more counters corresponding to each of plural track groups that are adjacent to each other; an updating module configured to update a count of one of the two or more counters corresponding to a second track group that is adjacent to a first track group of the plural track groups when information has been recorded on the first track group; a determining module configured to determine an attribute of the second track group based on the updated count of the one counter; and a rewriting module configured to rewrite information recorded in the second track group based on the determined attribute.

Abstract: A system and method for magnetic transfer. A magnetic transfer device includes a plurality of pairs of magnetic field generating units that apply a magnetic field to a contact body which includes a master disk in close contact with a magnetic recording medium, wherein the master disk has a pattern of preformatted signals. The magnetic field generating units, falling within a specified length range, are moved in synchrony at a predetermined speed in the directions of the outer periphery while the contact body is caused to rotate by a rotation drive unit. The system and method provide a magnetic transfer method and a magnetic transfer device that, by reducing the area of magnetic field generating units that apply a transfer magnetic field, can reduce an attractive force (or repulsive force) between the magnets, and furthermore, shorten a processing time for the transfer.

Abstract: Disclosed are a method and system for distinguishing spatial and thermal defects on perpendicular media. The magnetic domains of the perpendicular media are oriented to have a first polarity, scanned using a read head, oriented to have a second polarity and scanned again. The signals from the read head are combined to produce output signals having improved signal to noise ratios from which the locations of spatial and thermal defects can be identified and distinguished.

Abstract: Embodiments of the invention broadly contemplate systems, methods and arrangements for managing Adjacent Track Interference (ATI) risk through intelligent management of a table that logs individual tracks creating a risk of ATI in tracks adjacent thereto. Embodiments of the invention provide that tracks considered being at low risk for creating ATI be ejected from the table in order to maintain a track-level log of manageable size.

Abstract: Systems and methods for performing refresh operations using write/read commands are provided. In one embodiment, a disk drive comprises a disk partitioned into a plurality of refresh zones, a head configured to write data to and read data from the disk, and a controller. The controller is configured to receive an access command, to read data from at least one of the refresh zones using the head in response to the access command, to check a condition of the read data, and to determine whether to refresh the at least one refresh zone based on the condition of the read data, wherein the read data includes data from a portion of the at least one refresh zone not being accessed by the access command.

Abstract: An apparatus includes a recording media including a substrate, a plurality of tracks of magnetic material on the substrate, and a non-magnetic material between the tracks; a recording head having an air bearing surface positioned adjacent to the recording media, and including a magnetic pole, an optical transducer, and a near-field transducer, wherein the near-field transducer directs electromagnetic radiation onto tracks to heat portions of the tracks and a magnetic field from the magnetic pole is used to create magnetic transitions in the heated portions of the tracks; and a plasmonic material positioned adjacent to the magnetic material to increase coupling between the electromagnetic radiation and the magnetic material.

Abstract: A hard disk drive that includes a disk with data written onto a plurality of tracks, a spindle motor that rotates the disk, and a head that is coupled to the disk. The disk drive also includes a circuit that writes data onto a first writable shingle band of tracks if the first writable shingle band is adjacent to a guard band of tracks. The first writable shingle band includes a number of tracks that is a function of a head width. The guard band of tracks is capable of becoming a writable shingle band. Changing the designation of a shingle band between guard and writable creates floating guard bands. The creation of floating guard bands allows for the writing of a single band without having to move and restore adjacent tracks until reaching a fixed guard band as required in the prior art.

Abstract: A data storage device is disclosed with at least two partitions and a set of switches to separately enable and disable read and write operations to each of the partitions, wherein read and/or write operations for at least one of the partitions is disabled when the data storage device is accessible by one or more potentially malicious processes. In one embodiment, there are five partitions for (1) operating systems and trusted applications, (2) applications from non-trusted sources, (3) confidential data, (4) non-confidential data, and (5) all other data. A mode switch can be used to enable and disable reading and writing for each of the partitions according to a predetermined set of rules that effectively prevent viruses and other malware from altering or accessing programs and data.

Abstract: An information-processing apparatus includes a processing unit that compresses inputted data to produce compressed data of a first compressed format. The information-processing apparatus also includes a storage unit that stores the compressed data in a storage medium. The processing unit decompresses data, stored in the storage medium, of a second compressed format to produce decompressed data. Further, the processing unit controls the storage unit to store the compressed data of the first compressed format in the storage medium while the processing unit simultaneously decompresses the data, stored in the storage medium, of the second compressed format and reproduces the decompressed data. The first compressed format is different than the second compressed format.

Abstract: An information recording and reproducing apparatus 1 having a high efficiency of information transfer includes one or more recording media forming a plurality of recording surfaces, a plurality of heads respectively disposed on the recording surfaces, a first actuator for supporting the heads and moving the heads uniformly, a plurality of second actuators provided one for an associated one of the heads, the second actuators moving the heads independently relative to the first actuator, recording processing circuits for simultaneously outputting recording signals, and reproducing processing circuits simultaneously supplied with reproduced signals read out by the heads to reproduce information from the reproduced signals.

Abstract: According to one embodiment, a test device for a storage device includes: a module configured to acquire from the storage device a value corresponding to a signal level read from a magnetic disk through a magnetic head of the storage device, at a first timing at which an initial power of 0 or greater is supplied to a heater in the head and at a second timing at which a power to the heater is returned to the initial power after the power to the heater has been increased from the initial power, a periphery of a head element in the head has been expanded by the heater, and the element has been protruded toward a magnetic disk side; and a determiner configured to determine whether plastic deformation has occurred in the periphery of the element based on a difference between the values obtained at the first and second timings.

Abstract: Disclosed are a method and system for distinguishing spatial and thermal defects on perpendicular media. The magnetic domains of the perpendicular media are oriented to have a first polarity, scanned using a read head, oriented to have a second polarity and scanned again. The signals from the read head are combined to produce output signals having improved signal to noise ratios from which the locations of spatial and thermal defects can be identified and distinguished.

Abstract: Systems and techniques relating to interpreting signals on a channel having an asymmetrical signal amplitude response include an integrated circuit device including: an input to receive digital data corresponding to an asymmetry corrected analog signal of a read channel; an input to receive sequence data from a discrete time sequence detector, the sequence data generated by the discrete time sequence detector based on the digital data; an output to provide a coefficient adjustment to affect asymmetry correction of the analog signal; and circuitry to generate the coefficient adjustment based on an estimate of non-linearity for the read channel, the estimate derived from the digital data and the sequence data.

Abstract: A method of detecting skip track erasure for a head and disk of a disk drive is disclosed. N tracks are DC erased, and a periodic pattern is written to the disk at a target track within the DC erased tracks. The periodic pattern is substantially comprised of a high frequency component greater than 450 MHz. After writing the periodic pattern to the target track at least twice, at least two of the DC erased tracks other than the target track are read to generate respective read signals. The read signals are processed to detect a skip track erasure event.

Abstract: An audiocassette adapter (10) for coupling a mobile wireless communication station (20) to an audiocassette player, including a cassette head coupling device (12), a cassette adapter insertion detect switch (14), a mobile wireless communication station coupling device (50) having a mobile wireless communication station audio input coupled to the cassette head coupling device, the mobile wireless communication station coupling device having an insertion detect signal output (54) coupled to the cassette adapter insertion detect switch.

Abstract: Provided is a magnetic reproducing method that enables a thin-film magnetic head including a head element for reading data signals which has a noise in its output due to a low temperature to bring out an excellent read characteristic in which the noise is suppressed even under the use environment with the low temperature. The magnetic reproducing method comprises the steps of: heating a head element for reading data signals which has a noise in its output due to a low temperature; and performing a read operation by using the head element for reading data signals under condition that the head element is increased in temperature.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of tracks, and a head actuated over the disk. A plurality of refresh zones are defined, wherein each refresh zone corresponds to a plurality of the tracks. Data is written to a first refresh zone, and a first zone counter is updated for a second refresh zone at a first rate. Data is written to a third refresh zone, and the first zone counter is updated for the second refresh zone at a second rate different than the first rate.

Abstract: A data storage device includes a first filter that generates a short DC equalization target in response to a read back signal generated from magnetic patterns that are recorded on a storage medium using perpendicular recording. The data storage device also includes a first detector that generates an output sequence in response to the short DC equalization target. The data storage device also includes a high pass filter that attenuates DC components of the short DC equalization target and that passes low frequency components of the short DC equalization target above a cutoff frequency to generate a filtered signal. The data storage device also includes a second detector that processes the output sequence in response to the filtered signal.

Abstract: A data recording component includes a read transducer and a write transducer. A thermoelectric device generates heat flow between the read transducer and the write transducer. The heat flow is conducted by thermal conductors. A controlled current source provides current to the thermoelectric device that changes polarity to change directions of the heat flow and thereby vary a gamma ratio of transducer protrusion.

Abstract: Disclosed are a method and system for distinguishing spatial and thermal defects on perpendicular media. The magnetic domains of the perpendicular media are oriented to have a first polarity, scanned using a read head, oriented to have a second polarity and scanned again. The signals from the read head are combined to produce output signals having improved signal to noise ratios from which the locations of spatial and thermal defects can be identified and distinguished.

Abstract: Hard disk drive preamplifier timers and methods to calibrate hard disk drive preamplifier timers are disclosed. A timer in a hard disk drive preamplifier comprises a first switch to selectively store charge in a storage device based on an input signal, the storage device receiving a first current and storing the charge to cause the storage device to have a first voltage that increases at a first rate; a compensation device to cause the first voltage to be substantially equal to a second voltage after a predetermined time period; and a trigger to output a signal when the first voltage is substantially equal to the second voltage, the predetermined time period controlling a transition time between a first hard disk drive operating condition and a second hard disk drive operating condition different than the first operating condition.

Abstract: Systems and techniques relating to interpreting signals on a channel having an asymmetrical signal amplitude response. A signal processor, such as a read channel transceiver device usable in a magnetic recording system, includes an asymmetry correction circuit configured to receive an analog signal and to compensate for asymmetry in the received analog signal, a signal equalizer configured to receive an input signal responsive to an output of the asymmetry correction circuit and to generate an equalized signal, a discrete time sequence detector operable to examine the equalized signal, and a control circuit that provides a coefficient adjustment to the asymmetry correction circuit to affect the asymmetry compensation based on an estimate of non-linearity derived from the equalized signal and an output of the discrete time sequence detector. The estimate can be a least mean squared estimate of the non-linearity in the equalized signal.

Abstract: The present invention is directed to a method and apparatus for bulk erasure of disk drives. According to the novel invention, one or more relatively small-sized permanent magnets or electromagnets are configured to be brought into close proximity to a particular disk surface of the disk drive and to produce a concentrated magnetic force that erases the disk. Notably, the magnets are sized and configured to create a focused magnetic field, and correspondingly to prevent stray magnetic fields, which could otherwise be harmful to magnetically sensitive components of the disk drive, such as motor magnets. The magnets may be configured to gain access to the disk surface through one or more openings on a covered disk drive, e.g., through an actuator and/or servo track writer opening. The magnets and resultant focused magnetic field may be large enough to offer substantially full radial coverage of the disk, or may be smaller and configured to move (e.g.

Abstract: In the magnetic recording apparatus, a recording layer is formed in a concavo-convex pattern, and recording elements are formed of convex portions of the concavo-convex pattern. Furthermore, the following equation (I) BL?ERL?BL+2×GL??(Equation (I)) is satisfied in each of tracks, where BL represents a length of the recording element in a circumferential direction, GL represents a length of a gap between the recording elements in the circumferential direction, and ERL represents an effective recording length which is a length of an effective recording area ER in the circumferential direction, the effective recording area ER being created on a magnetic recording medium by a heating head and a recording head.

Abstract: A method for providing feedback current cancellation comprises providing an amplifier with an input, an output, and at least one stage, feeding back a first current based on the output of the amplifier to the input of the amplifier, and substantially cancelling the first current by supplying a second current to the input of the amplifier.

Abstract: An imaging apparatus includes an imaging unit, a recording and reproduction unit configured to record a serial moving image signal generated by the imaging unit as one cut on a recording medium during a period from an instruction to start photographing to an instruction to stop photographing, and to reproduce a moving image signal recorded on the recording medium, a mode setting unit configured to selectively setting one of a reproduction mode for reproducing a moving image signal recorded on the recording medium and a recording mode for recording a moving image signal on the recording medium, and a control unit configured to, responsive to an instruction to start reproduction in the reproduction mode, control the recording and reproduction unit to reproduce a moving image signal starting with a cut recorded first among a plurality of cuts recorded within a predetermined time period.

Abstract: Embodiments in accordance with the present invention reduce the number of errors caused by the aged deterioration of a heater for adjusting the clearance between a head and a disk. According to one embodiment, a thermal fly height control (TFC) controller executes the measurement of a resistance value of a heater in a predetermined timing. The TFC controller judges whether or not the measured resistance value falls within a predetermined reference range. If the measured resistance value falls within the reference range, the processing ends without performing any other processing. If the measured resistance value goes out of the reference range, the TFC controller executes error handling processing in response to a resistance failure. As one of the error handling processing, the TFC controller notifies the host that the abnormality (resistance failure) has been detected in the resistance value of the TFC heater.

Abstract: To effectively suppress a signal in a low frequency region in which the medium noise and the signal distortion are concentrated, and in order to effectively utilize a detected component of the reproduced signal in the low frequency region, a target of partial response equalization to the perpendicularly recorded/reproduced signal is set so that the low-frequency component around the direct current is suppressed to a regulated quantity for both the effective suppression and the effective utilization. Accordingly, a maximum-likelihood decoding process is carried out through the target of partial response equalization. Reliability of data detection is made higher and a signal-to-noise ratio is improved, so that the noise from the recording medium can be reduced more and it is possible to provide a high-density magnetic recording/reproducing apparatus.

Abstract: A read-channel module includes a variable-gain amplifier (VGA) module, an analog-to-digital converter (ADC) module, an amplitude measuring module, a gain adjusting module, and a zero phase start (ZPS) module. The VGA module has a variable gain, amplifies input signals, and generates amplified signals. The ADC module converts the amplified signals from analog to digital format and generates samples. The amplitude measuring module receives N of the samples and measures amplitudes of the N samples, where N is an integer greater than 1. The gain adjusting module communicates with the amplitude measuring module and selectively adjusts the variable gain of the VGA module based on the amplitudes. The zero phase start (ZPS) module communicates with the amplitude measuring module, receives the samples, and selectively generates phase information from the samples based on the amplitudes.

Abstract: A thermally assisted magnetic recording system is provided to achieve excellent thermal resistance and low noise. In one embodiment, a magnetic recording medium is used, in which the magnetic intergrain exchange coupling is large to let the magnetization be thermally stable by coupling the magnetic grains constituting the recording layer at room temperature (the temperature maintaining the magnetization) and reduced by heating during recording to let the recording magnetization transition slope become steep. Parameter A normalizing the slope around the coercivity of the MH-loop of the medium is 1.5?A<6.0 at room temperature, and it becomes approximately 1.0 with heating.

Abstract: Methods and recording systems are configured for recording different data simultaneously at two different depths of a tilted magnetic medium, the tilted magnetic medium having a hard axis of magnetization, the axis being out of a plane of the medium and at an angle of ?10 to ?80 degrees with respect to a direction along which data are recorded, the medium being capable of having two depths of recording. A method embodies writing with selected magnetic fields whose amplitudes and whose angles with respect to the medium hard axis direction differ at the two depths of the medium such that the recorded direction of magnetization at the respective two depths can be set independently.

Abstract: A mechanical transport device includes a system for transport; and a hard disk drive attached to the system. The hard disk drive comprises a magnetic recording disk to record data, a head to read or write the data to or from the disk, and a drop sensor designed to sense a shock condition. The system for transport may be a vehicle such as a car. Additional systems are also presented.

Abstract: The optimum head-field intensity for saturation recording is assumed to be 560×103 A/m or more. Under a condition where the recording track width of an information recording medium is equal to or less than 60 nm, the optimum head-field intensity Y satisfies the following inequalities (1) and (2): Y?(X2?119×X+4135)×1000??(1) Y?(X2?119×X+const)×1000??(2) where X denotes the nondimensional value of the recording track width divided by 10?9 m, and Y denotes a magnetic field (expressed in units of A/m) which a magnetic pole for head-field application applies to the center of the information recording medium in the direction of the thickness thereof. Note that const=?0.8×v2+33.7×v+4250 if the relative velocity v between the head and the medium at the position of the head is less than 20 m/sec, or const=4600 if the velocity v is equal to or more than 20 m/sec.

Abstract: An apparatus for producing an optical spot on the order of 25 nm in a recording media. The apparatus includes an optical transducer comprising a waveguide which defines an aperture adjacent to an air bearing surface of the transducer adjacent a recording media. The transducer includes a protrusion extending beyond the plane of the air bearing surface extending toward the recording media.

Abstract: This invention protects the data on the hard disk from viruses and hackers by making it possible to turn off any head whether it is a read head or a write head of any arm of the hard disk by providing switches, so when we surf the Internet we turn off the read/write heads of the platter surface which contains the confidential data and we always turn off the write head of the platter surface which contains the Windows programs and other program files so the programs data are always protected and at the same time it is always readable, after we logoff the Internet we turn off the read/write heads of the platter surface used to save Internet data onto it thus we will never have any virus moving from this platter surface to the rest of the hard disk platters surfaces.

Abstract: A method and an apparatus for copying data of a disc drive are provided. The method includes: determining whether the first disc drive has a predetermined jumper pin connection by identifying which of a plurality of jumper pins in a jumper block of the first disc drive are connected, the jumper block being used to determine an operation mode of the first disc drive; transmitting a copy command from the first disc drive to the second disc drive if the first disc drive has the predetermined jumper pin connection; and copying data recorded in the first disc drive to the second disc drive in response to the copy command. Accordingly, it is possible to copy data recorded in a first hard disc drive (HDD) to a second HDD without the aid of an additional host.

Abstract: A media storage device which reads and writes data from and to a storage medium using a head prevents in advance data loss due to thermal relaxation of data recorded on the storage medium. Management information is created, in units of received write commands, for holding the recording areas on the storage medium of the write data and signal quality information; the management data is stored in a management table, and signal quality is measured, updated, and used in re-recording judgements, in write command units. Thermal relaxation state management can be performed in write command units; thermal relaxation processing is simple, and moreover degradation of recorded data due to thermal relaxation can be detected accurately, and data loss can be prevented.