Magnetic disk device

Abstract

The embodiment of the invention relates to a magnetic disk device. A magnetic disk device is provided with a disk (DK), a head (HD), a read processing unit (63), a write processing unit (62), an error correction unit (64), an adjustment unit (65), a correction limit prediction unit (66), and a determination unit (67). In a first writing period, an adjustment unit (65) derives a first predicted excess amount that varies in accordance with a distance at which a head (RHD) seeks a trace, and derives a predicted upper threshold value, and a correction limit prediction unit (66) calculates a first cumulative predicted excess amount. The determination unit (67) causes the write processing unit (62) to continue the write processing when it is determined that the first cumulative prediction excess amount is equal to or less than the prediction upper limit threshold value. When the determination unit (67) determines that the first cumulative prediction excess amount exceeds the prediction upper limit threshold value, the determination unit (67) causes the write processing unit (62) to suspend the write processing.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2024-157235 (filed on September 11, 2024). This application incorporates the entire contents of the basic application by reference to that basic application. Technical Field

[0002] Embodiments of the present invention relate to disk drives. Background Technology

[0003] As disk devices, known types include conventional magnetic recording (CMR) type disk devices that write to multiple tracks at intervals in the radial direction of the disk, shingled magnetic recording (SMR) type disk devices that write to multiple tracks in an overlapping manner in the radial direction of the disk, and hybrid recording type disk devices that select and perform conventional recording and shingled recording. Summary of the Invention

[0004] One embodiment of the disk drive includes:

[0005] The disk has a first data track and a second data track adjacent to each other in the recording layer. Each of the first data track and the second data track includes a plurality of object sectors that are objects to be written. From the view of the second data track, the first data track is located in a first direction parallel to the radial direction of the disk.

[0006] The head has a write head for writing data to the recording layer and a read head for reading data from the recording layer;

[0007] The read processing unit is capable of performing seek processing to enable the read head to seek;

[0008] The write processing unit is capable of performing write processing on the data written to the recording layer;

[0009] The error correction unit performs error correction on the data of one or more damaged object sectors among the plurality of object sectors of the first data track that are determined to be corrupted.

[0010] Adjustment Department;

[0011] Correction limit prediction unit; and

[0012] Judgment Department

[0013] The first write period is the period between when the write processing unit performs the write processing on the plurality of object sectors of the first data track and when it performs the write processing on the plurality of object sectors of the second data track.

[0014] The read processing unit performs a first seek process to cause the read head to seek a track, moving the read head a first distance so that the write head faces the second data track.

[0015] The adjustment part,

[0016] A first predicted overshoot is derived, which is the predicted overshoot by which the position of the write head exceeds a reference radius position in the first direction during the first write, and varies based on the distance required for the read head to seek.

[0017] A prediction upper limit threshold is derived, which is a constant representing the limit of the feasible range of error correction for the first data track.

[0018] The correction limit prediction unit, whenever writing data to each of the target sectors of the second data track, measures the measured excess amount by which the position of the write head exceeds the reference radius position in the first direction, updates the accumulated measured excess amount, and calculates a first cumulative predicted excess amount by adding the first predicted excess amount to the accumulated measured excess amount.

[0019] The judgment unit

[0020] If it is determined that the first cumulative prediction exceeds the upper limit threshold of the prediction, the write processing unit continues to perform the write processing on the second data track.

[0021] If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the second data track.

[0022] In addition, one embodiment of the disk device includes:

[0023] The disk has a first data track and a second data track adjacent to each other in the recording layer. Each of the first data track and the second data track includes a plurality of object sectors as objects to which data is written. From the view of the second data track, the first data track is located in a first direction parallel to the radial direction of the disk.

[0024] The head has a write head for writing data to the recording layer and a read head for reading data from the recording layer;

[0025] The read processing unit is capable of performing seek processing to enable the read head to seek data.

[0026] The write processing unit is capable of performing write processing on the data written to the recording layer;

[0027] The error correction unit performs error correction on the data of one or more damaged object sectors among the plurality of object sectors of the first data track that are determined to be corrupted.

[0028] Adjustment Department;

[0029] Correction limit prediction unit; and

[0030] Judgment Department

[0031] The first write period is the period between when the write processing unit performs the write processing on the plurality of object sectors of the first data track and when it performs the write processing on the plurality of object sectors of the second data track.

[0032] The read processing unit performs a first seek process to cause the read head to seek a track, moving the read head a first distance so that the write head faces the second data track.

[0033] The adjustment part,

[0034] A first predicted overshoot is derived, which is a predicted overshoot that the position of the write head exceeds a reference radius position in the first direction during the first write, varying according to the distance the read head seeks.

[0035] A prediction upper limit threshold is derived. This prediction upper limit threshold is a variable representing the limit of the feasible range of error correction for the first data track. The greater the number of prediction overshoots, including the first prediction overshoot, the smaller the prediction upper limit threshold will be.

[0036] The correction limit prediction unit, whenever writing data to each of the target sectors of the second data track, measures the measured excess amount by which the position of the write head exceeds the reference radius position in the first direction, updates the accumulated measured excess amount, and calculates a first cumulative predicted excess amount by adding the first predicted excess amount to the accumulated measured excess amount.

[0037] The judgment unit

[0038] If it is determined that the first cumulative prediction exceeds the upper limit threshold of the prediction, the write processing unit continues to perform the write processing on the second data track.

[0039] If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the second data track.

[0040] According to this embodiment, a disk device can be provided that can predict, in association with seek operations, whether the error correction of a data track on the disk has reached its limit. Attached Figure Description

[0041] Figure 1 This is a block diagram illustrating the configuration of a disk device according to one embodiment.

[0042] Figure 2 This is a perspective view showing a portion of the aforementioned disk drive, and a view showing multiple disks and multiple heads.

[0043] Figure 3 This is a schematic diagram illustrating an example of the configuration of multiple servo areas and multiple data areas of a disk according to the above embodiment.

[0044] Figure 4 It is shown Figure 3 The diagram shows the three tracks of the user data area of ​​the disk undergoing record-keeping processing, and the write head.

[0045] Figure 5 It is shown Figure 3 The diagram shows the three tracks of the media cache on the disk, which is used for normal recording, and the write head.

[0046] Figure 6 This is a schematic diagram illustrating an example of data write processing on a disk.

[0047] Figure 7 It is shown Figure 6 The diagram shows two bands and one guard band in the user data area.

[0048] Figure 8 It is shown Figure 6 The diagram shows three sectors in one track of the strip.

[0049] Figure 9 It is shown Figure 7 The diagram showing two strips and one guard strip is used to illustrate multiple object sectors and multiple unused sectors.

[0050] Figure 10This is a schematic diagram illustrating an example of track 1 and track 2, assuming that the disk device does not have the function of performing track-by-track error correction on the data of the track. It is a diagram for illustrating the write processing of track 1 and track 2. It is a diagram for illustrating the state of continuing write processing of track 2 until the error correction of track 1 on a sector-by-sector basis reaches its limit. It is a graph showing the change of BER relative to track 1 and the change of BER relative to positioning error, respectively.

[0051] Figure 11 This diagram illustrates an example of tracks 1 and 2, assuming the disk device does not have the function of performing track-by-track error correction on the data of the tracks. It is a diagram for explaining the write processing of tracks 1 and 2. It is a diagram for explaining the state in which the write off-track slice is limited (strictly) with the judgment value set to be smaller than the track margin, and the write processing of track 2 is terminated when the positioning error is detected to exceed the reference radius position. It is a diagram that shows the change of BER relative to track 1 and the change of BER relative to the positioning error, respectively.

[0052] Figure 12 This is a schematic diagram showing an example of the first and second tracks of the aforementioned disk device, which has the function of performing track-by-track error correction on the data of the tracks. It is a diagram for explaining the write processing of the first and second tracks. It is a diagram for explaining the state in which the decision value is set to a (relaxed) write track deviation limit that is larger than the track margin, and the write processing of the second track continues until the track-by-track error correction of the first track reaches the limit. It is a diagram that shows the change of BER relative to the first track and the change of BER relative to the positioning error, respectively.

[0053] Figure 13 It is a table showing the presence or absence of ECC on the magnetic track in the first to third modes of the first and second write operations, the function name of the control DOL, the handling content when the positioning error exceeds the reference radius position, the setting of the prediction upper limit threshold, and the setting of the prediction excess amount.

[0054] Figure 14 It is a bar chart showing the change in the predicted excess amount of the above-mentioned disk device relative to the seek distance.

[0055] Figure 15 This is a graph showing the changes in positioning error, cumulative excess, and cumulative prediction excess when the write process is performed on the second track in the second and third modes of the second write operation described above. It is also a graph showing the case where the prediction upper limit threshold is a constant.

[0056] Figure 16 This is a graph showing the changes in positioning error, cumulative excess, and cumulative prediction excess when the write process is performed on the second track in the second and third modes of the second write operation described above. It is also a graph showing the case where the prediction upper limit threshold is a variable.

[0057] Figure 17 This is a bar chart showing the number (occurrence rate) of PTS (Packet Switching) when the disk device uses the first method of the second write operation and the second method of the second write operation.

[0058] Figure 18 This is a flowchart illustrating the write processing method for the nth target sector of the second track in the write processing method according to the above embodiment, and is a diagram of the disk device employing the first write operation during the first write.

[0059] Figure 19 This is a flowchart illustrating the write processing method for the nth target sector of the second track in the write processing method according to the above embodiment, and is a diagram of the second mode in which the disk device employs the second write operation during the first write.

[0060] Figure 20 Is following Figure 19 The following is a flowchart of the above-described write processing method.

[0061] Figure 21 This is a flowchart illustrating the write processing method for the nth target sector of the second track in the write processing method according to the above embodiment. It is a diagram of the third mode in which the disk device employs the second write operation during the first write period and the second write period.

[0062] Figure 22 Is following Figure 21 The following is a flowchart of the above-described write processing method.

[0063] Figure 23 Is following Figure 22 The following is a flowchart of the above-described write processing method.

[0064] Explanation of reference numerals in the attached figures

[0065] 1. Disk Device; 60MPU; 61. Read / Write Processing Unit; 62. Write Processing Unit; 63. Read Processing Unit; 64. Error Correction Unit; 65. Adjustment Unit; 66. Correction Limit Prediction Unit; 67. Judgment Unit; 68. Management Unit; 70. Volatile Memory; 80. Buffer Memory; 90. Non-Volatile Memory; 100. Host; 110. System Controller; 120. Driver IC; 130. Header Amplifier IC; 140. R / W Channel; 150. HDC; 24. VCM; 30. Arm; DK Disk; L Recording Layer; TR, STR, CTR Tracks; SC Sector; RSC Object Sector; CSC Damaged Object Sector; HD Head; WHD Write Head; RHD Read Head; PE Positioning Error; TM Track Margin; PO Reference Radius Position; WOS Write Track Deviation Limit; d1 Radius Direction; d2 Travel Direction; d3 Rotation Direction; d5 Overlap Write Direction; Da First Direction; Db Second Direction. Detailed Implementation

[0066] Hereinafter, a disk drive 1 according to one embodiment will be described in detail with reference to the accompanying drawings. First, the configuration of the disk drive 1 will be described. Figure 1 This is a block diagram illustrating the configuration of the disk device 1 according to this embodiment. In this embodiment, the disk device 1 is a hybrid recording type disk device that selectively performs both conventional recording and watt-hour recording. However, the techniques described later can also be applied to watt-hour recording disk devices, and also to conventional recording disk devices.

[0067] like Figure 1 As shown, the disk drive 1 includes multiple (e.g., 1 to 10) disks (disks) DK as recording media, a spindle motor (SPM) 20 as a drive motor, a head stack assembly 22, a driver IC 120, a head amplifier integrated circuit (hereinafter referred to as a head amplifier IC or preamplifier) ​​130, volatile memory 70, buffer memory (buffer) 80, non-volatile memory 90, and a system controller 110 as a single-chip integrated circuit. Furthermore, the disk drive 1 is connected to a host system (hereinafter simply referred to as a host) 100.

[0068] Each disk drive (DK) is formed, for example, with a diameter of 97 mm (3.8 inches) and has a recording layer (magnetic recording layer) on both sides. Furthermore, although the disk drive 1 in this embodiment has 1 to 11 disk drives, the number of disk drives is not limited to this.

[0069] The head stack assembly 22 can control the head HD mounted on the arm 30 to move to a target position on the disk DK by driving the voice coil motor (hereinafter referred to as VCM) 24, that is, it can perform track seeking. The VCM 24 functions as an actuator.

[0070] Regarding disk DK, its writable data area is allocated a user data area U that users can use, and a system area S that writes information required for system management.

[0071] The HD head records and reproduces information on the disk DK. The HD head is primarily composed of a slider and includes a write head (WHD) and a read head (RHD) mounted on the slider. The write head (WHD) writes data to the recording layer of the disk DK. The read head (RHD) reads data from the data tracks of the recording layer of the disk DK.

[0072] Sometimes the "center part of the head HD" is called "head HD", the "center part of the write head WHD" is called "write head WHD", and the "center part of the read head RHD" is called "read head RHD". Sometimes the "center part of the write head WHD" is simply called "head HD", and sometimes the "center part of the read head RHD" is simply called "head HD".

[0073] The driver IC120 controls the drive of SPM20 and VCM24 under the control of the system controller 110 (specifically, MPU60 described later). SPM20 supports and rotates multiple disks DK.

[0074] The head amplifier IC130 includes a read amplifier and a write driver. The read amplifier amplifies the read signal read from the disk DK and outputs it to the system controller 110 (specifically, the read / write (R / W) channel 140, described later). The write driver outputs a write current corresponding to the signal output from the R / W channel 140 to the head HD.

[0075] Volatile memory 70 is a semiconductor memory whose data is lost when the power supply is cut off. Volatile memory 70 stores data required for processing by various parts of disk drive 1. Volatile memory 70 is random access memory (RAM). Volatile memory 70 can also be, for example, DRAM (Dynamic Random Access Memory). Furthermore, volatile memory 70 can also be SDRAM (Synchronous Dynamic Random Access Memory).

[0076] The buffer memory 80 is a semiconductor memory that temporarily records data transmitted and received between the disk drive 1 and the host computer 100. Furthermore, the buffer memory 80 may be integrated with the volatile memory 70. The buffer memory 80 is a volatile RAM. Examples of types include DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), and MRAM (Magnetoresistive Random Access Memory).

[0077] The buffer memory 80 includes areas used as read cache and write cache, temporarily storing commands received from the host 100, etc.

[0078] Non-volatile memory 90 is a semiconductor memory that retains data even when the power supply is cut off. Non-volatile memory 90 is, for example, a NAND-type flash read-only memory (FROM). Alternatively, non-volatile memory 90 can also be a NOR-type FROM.

[0079] The system controller (controller) 110 is implemented, for example, using a large-scale integrated circuit (LSI) known as a system-on-a-chip (SoC), which integrates multiple components onto a single chip. The system controller 110 includes a read / write (R / W) channel 140, a hard disk controller (HDC) 150, and a microprocessor (MPU) 60. The system controller 110 is electrically connected to a driver IC 120, a head amplifier IC 130, volatile memory 70, buffer memory 80, non-volatile memory 90, and a host 100.

[0080] R / W channel 140 performs signal processing on read data transferred from disk DK to host 100 and write data transferred from host 100, according to instructions from MPU 60 (described later). R / W channel 140 has circuitry or functions for modulating write data. Additionally, R / W channel 140 has circuitry or functions for measuring the signal quality of read data. R / W channel 140 is electrically connected, for example, to head amplifier IC 130, HDC 150, and MPU 60.

[0081] HDC150 controls the data transfer between host 100 and R / W channel 140 according to instructions from MPU60. HDC150 is electrically connected to, for example, R / W channel 140, MPU60, volatile memory 70, buffer memory 80 and non-volatile memory 90.

[0082] The HDC150 has a gate generation unit. Based on commands from the host 100, instructions from the MPU60, etc., the gate generation unit generates various gates, such as write gates, read gates, and servo gates, and outputs them to the R / W channel 140, such as the gate detection unit. Hereinafter, "activating a predetermined gate" is sometimes referred to as "asserting a predetermined gate." Additionally, "disabling a predetermined gate" is sometimes referred to as "negate a predetermined gate." "Enabling a predetermined gate" and "negate a predetermined gate" sometimes also include the meaning of "generating a predetermined gate." Furthermore, the gate generation unit may also be included in the R / W channel 140 or the MPU60.

[0083] The R / W channel 140 has a gating detection unit. The gating detection unit detects whether various strobes, such as write strobe, read strobe, and servo strobe, are in a valid or invalid state.

[0084] For example, the gating detection unit performs write processing if it detects that the write gating is valid, and stops (stops) the write processing if it detects that the write gating is invalid.

[0085] Furthermore, the gating detection unit performs read processing if a read gating is detected as valid, and stops read processing if an invalid read gating is detected. Similarly, the gating detection unit performs servo read processing if a servo gating is detected as valid, and stops servo read processing if an invalid servo gating is detected. The gating detection unit can also be located within the HDC150 or MPU60.

[0086] MPU60 is the control unit that controls the various parts of disk drive 1, and is the main controller. MPU60 controls VCM24 via driver IC120, performing servo control for head HD positioning. MPU60 controls the write operation of data to disk DK and selects the destination for the write data transferred from host 100. Additionally, MPU60 controls the read operation of data from disk DK and controls the processing of read data transferred from disk DK to host 100. MPU60 is connected to various parts of disk drive 1. For example, MPU60 is electrically connected to driver IC120, R / W channel 140, and HDC150.

[0087] The MPU 60 includes a read / write processing unit 61, an error correction unit 64, an adjustment unit 65, a correction limit prediction unit 66, a judgment unit 67, and a management unit 68. The MPU 60 executes the processing of these units, such as the read / write processing unit 61, error correction unit 64, adjustment unit 65, correction limit prediction unit 66, judgment unit 67, and management unit 68, in the firmware. Furthermore, these units can also be included as circuitry within the MPU 60.

[0088] The read / write processing unit 61 includes a write processing unit 62 and a read processing unit 63. According to commands from the host 100, the write processing unit 62 controls the write processing of data, and the read processing unit 63 controls the read processing of data, causing the read head RHD to read data from the disk DK. The read processing unit 63 can perform seek processing to cause the read head RHD to seek. The write processing unit 62 can perform write processing to write data to the recording layer of the disk DK. The read / write processing unit 61 controls the VCM 24 via the driver IC 120, positioning the head HD at a target position (a predetermined radius position) on the disk DK, and performing read or write processing.

[0089] Figure 2 This is a perspective view showing a portion of disk drive 1, and a view showing multiple disks (DK) and multiple head (HD).

[0090] like Figure 2 As shown, in the circumferential direction, the direction of rotation of disk DK is called the rotation direction d3. Furthermore, although in Figure 2 In the example shown, the rotation direction d3 is represented as counterclockwise, but it can also be the opposite direction (clockwise). Additionally, the travel direction d2 of the head HD relative to the disk DK is opposite to the rotation direction d3. The travel direction d2 is the direction in which the head HD sequentially writes and reads data from the disk DK in the circumferential direction; that is, the direction in which the head HD travels relative to the disk DK in the circumferential direction.

[0091] The disk drive 1 includes i disks, DK1 to DKi, and j heads, HD1 to HDj. In this embodiment, the number of heads HD is twice the number of disks DK (j = 2 × i).

[0092] Disks DK1 to DKi are arranged coaxially and overlapped with a gap between them. Disks DK1 to DKi have the same diameter. Here, terms such as "same," "identical," "consistent," and "equivalent" naturally include the meaning of being completely identical, as well as the meaning of having differences in degree that can be considered substantially the same. In addition, the diameters of disks DK1 to DKi may also be different from each other.

[0093] Each disk DK has recording layers L on both sides. For example, disk DK1 has a first recording layer La1 and a second recording layer Lb1 on the opposite side of the first recording layer La1. Disk DK2 has a first recording layer La2 and a second recording layer Lb2 on the opposite side of the first recording layer La2. Disk DKi has a first recording layer Lai and a second recording layer Lbi on the opposite side of the first recording layer Lai. Each first recording layer La is sometimes referred to as the surface or recording plane. Each second recording layer Lb is sometimes referred to as the back side or recording plane.

[0094] Furthermore, each of the first recording layers La is sometimes referred to as the back surface. In this case, each of the second recording layers Lb is sometimes referred to as the surface.

[0095] Each record layer L has a user data area U and a system area S. Record layer 1 La1 has a user data area Ua1 and a system area Sa1. Record layer 2 Lb1 has a user data area Ub1 and a system area Sb1. Record layer 1 La2 has a user data area Ua2 and a system area Sa2. Record layer 2 Lb2 has a user data area Ub2 and a system area Sb2. Record layer 1 Lai has a user data area Uai and a system area Sai. Record layer 2 Lbi has a user data area Ubi and a system area Sbi.

[0096] The track in user data area Ua1 (first recording layer La1) that is sandwiched between double dashed lines in the diagram is designated as track Ta1. The track in user data area Ub1 (second recording layer Lb1) that is located on the opposite side of track Ta1 is designated as track Tb1.

[0097] The track in user data region Ua2 (first recording layer La2) that is sandwiched between double dashed lines in the diagram is designated as track Tc1. The track in user data region Ub2 (second recording layer Lb2) that is located on the opposite side of track Tc1 is designated as track Td1.

[0098] The track in the user data area Uai (first recording layer Lai) that is sandwiched between the double dashed lines in the diagram is designated as track Te1. The track in the user data area Ubi (second recording layer Lbi) that is located on the opposite side of track Te1 is designated as track Tf1.

[0099] In this embodiment, magnetic tracks Ta1, Tb1, Tc1, Td1, Te1, and Tf1 are located on the same cylindrical surface.

[0100] Head HD faces the disk DK. In this embodiment, for each recording layer L of the disk DK, there is one head HD facing it. For example, head HD1 faces the first recording layer La1 of the disk DK1, writes data to the first recording layer La1, and reads data from the first recording layer La1. Head HD2 faces the second recording layer Lb1 of the disk DK1, writes data to the second recording layer Lb1, and reads data from the second recording layer Lb1.

[0101] Head HD3 faces the first recording layer La2 of disk DK2, writing data to and reading data from the first recording layer La2. Head HD4 faces the second recording layer Lb2 of disk DK2, writing data to and reading data from the second recording layer Lb2. Head HDj-1 faces the first recording layer Lai of disk DKi, writing data to and reading data from the first recording layer Lai. Head HDj faces the second recording layer Lbi of disk DKi, writing data to and reading data from the second recording layer Lbi.

[0102] Figure 3 This is a schematic diagram illustrating an example of the configuration of multiple servo areas (SV) and multiple data areas (DTR) of a single disk (DK) according to this embodiment. Figure 3 As shown, in the radial direction d1 of disk DK, the direction towards the outer periphery of disk DK is called the outer direction (outer side), and the direction opposite to the outer direction is called the inner direction (inner side).

[0103] exist Figure 3 In the data, the user data area U is divided into an inner peripheral region IR located in the inward direction, an outer peripheral region OR located in the outward direction, and a middle peripheral region MR located between the inner peripheral region IR and the outer peripheral region OR.

[0104] The disk DK has multiple servo areas (SVs) and multiple data areas (DTRs). The multiple servo areas (SVs) can, for example, extend radially in the radial direction of the disk DK and be discretely arranged at predetermined intervals in the circumferential direction. Alternatively, the multiple servo areas (SVs) can extend linearly from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. Or, the multiple servo areas (SVs) can extend spirally from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. Furthermore, the multiple servo areas (SVs) can, for example, be arranged in an island shape in the radial direction and discretely arranged at varying predetermined intervals in the circumferential direction.

[0105] Hereinafter, a single servo region SV in a predetermined track is sometimes referred to as a "servo sector". Additionally, a "servo region SV" is sometimes referred to as a "servo sector SV". A servo sector contains servo data. Hereinafter, the "configuration of several servo data items constituting a servo sector" is sometimes referred to as a "servo pattern". Furthermore, the "servo data written to a servo sector" is sometimes referred to as a "servo sector".

[0106] Multiple Data Regions (DTRs) are configured between multiple Servo Regions (SVs). For example, a Data Region DTR corresponds to the area between two consecutive Servo Regions (SVs) in the circumferential direction. Hereinafter, a single Data Region DTR in a predetermined track is sometimes referred to as a "data sector." Furthermore, a "Data Region DTR" is sometimes referred to as a "Data Sector DTR." Data sectors contain user data. Additionally, "user data written to a data sector" is sometimes referred to as a "data sector." Sometimes, a "data sector" is also referred to as "user data." Furthermore, a "pattern composed of several data items" is sometimes referred to as a "data pattern." Figure 3 In the example shown, the data pattern of the predetermined track consists of multiple servo data (servo sectors) and multiple user data (data sectors).

[0107] A servo zone (SV) has multiple zone servo zones (ZSVs). In addition to the zone servo zones (ZSVs), a servo zone (SV) may also include regions containing gaps (the offset between the circumferential positions of the two zone servo zones), regions containing servo data, and data regions (DTRs). The multiple zone servo zones (ZSVs) are discretely arranged along the radial direction (d1). Each of the multiple zone servo zones (ZSVs) extends along the radial direction (d1).

[0108] Sometimes, a single partitioned servo region (servo area) ZSV in a predetermined track is referred to as a "partitioned servo sector" or "servo sector". Furthermore, sometimes the "partitioned servo region (servo area) ZSV" is referred to as a "partitioned servo sector ZSV" or "servo sector ZSV". Sometimes, "servo data written to a partitioned servo sector" is referred to as a "partitioned servo sector" or "servo sector". Hereinafter, sometimes the "configuration of several servo data constituting a partitioned servo sector" is referred to as a "partitioned servo pattern" or "servo pattern". Hereinafter, sometimes a single servo area SV in a predetermined track is referred to as a "partitioned pattern sector".

[0109] In addition, "servo area SV" is sometimes referred to as "partition pattern sector". "At least one piece of data written to a partition pattern sector" is sometimes referred to as "partition pattern sector". A partition pattern sector includes at least one partition servo sector. Hereinafter, "the data pattern of a partition pattern sector" is sometimes referred to as "partition data pattern".

[0110] exist Figure 3 In the example shown, the servo region SV has partitioned servo regions ZSV0, ZSV1, and ZSV2. The partitioned servo regions ZSV0, ZSV1, and ZSV2 are arranged in a houndstooth pattern (alternating vertically and horizontally) in the radial direction. Alternatively, the partitioned servo regions ZSV0, ZSV1, and ZSV2 can be arranged in a stepped pattern in the radial direction.

[0111] Partition servo region ZSV2 is located on the inner periphery side of partition servo region ZSV1. Partition servo region ZSV0 is located on the outer periphery side of partition servo region ZSV1. For example, partition servo region ZSV2 is configured from the inner periphery region IR to the middle periphery region MR, partition servo region ZSV1 is configured from the inner periphery region IR to the outer periphery region OR, and partition servo region ZSV0 is configured from the middle periphery region MR to the outer periphery region OR. Hereinafter, in the predetermined servo region SV, the predetermined region in the radial direction where multiple partition servo regions ZSV are configured in the circumferential direction is sometimes referred to as the partition servo boundary region, dual servo region, or dual partition servo region ZB.

[0112] exist Figure 3 In the example shown, the primary servo regions SVO and secondary servo regions SVE are arranged alternately with intervals in the circumferential direction. For example, one secondary servo region SVE is configured between two consecutive primary servo regions SVO arranged with intervals in the circumferential direction. In other words, one secondary servo region SVE is configured between two consecutive primary servo regions SVO arranged with intervals in the circumferential direction. For example, when all servo regions SV of disk DK are sequentially assigned consecutive numbers, the primary servo region SVO corresponds to the odd-numbered servo region SV, and the secondary servo region SVE corresponds to the even-numbered servo region SV. Furthermore, two or more secondary servo regions SVE can also be configured between two consecutive primary servo regions SVO arranged with intervals in the circumferential direction.

[0113] The master servo region (SVO) and slave servo region (SVE) can, for example, consist solely of a servo region that reads and demodulates servo data as a whole (hereinafter, sometimes referred to as a normal servo region). Hereinafter, "reading and demodulating servo data" is sometimes referred to as "servo reading." The master servo region (SVO) and slave servo region (SVE) can also, for example, consist of a normal servo region and a servo region that reads servo data in a circumferential direction for a range smaller than the range of servo data read in the normal servo region (hereinafter, sometimes referred to as a short servo region).

[0114] Media cache M is allocated on disk DK. However, media cache M may not be configured on disk DK.

[0115] By using the aforementioned multiple servo data, it is possible to derive the positioning error of the head HD (e.g., the write head WHD).

[0116] In this embodiment, the example given is a disk DK with three partitions, but the number of partitions on the disk DK can be varied. The number of partitions on the disk DK can also be 30 to 40. Furthermore, each partition can have multiple bands. For example, each partition can have hundreds of bands.

[0117] Figure 4 It is shown Figure 3 The diagram shows the three tracks STR of the user data area U on the disk DK, which is used for tape recording, and the write head WHD. User data area U is the tape recording area. Within user data area U, data can be written sequentially in tape units; that is, tape recording is permitted.

[0118] like Figure 4 As shown, the write head WHD can write data sequentially to disk DK in the direction of travel d2. Figure 3 The read head RHD shown can also read data written to disk DK sequentially in the direction of travel d2.

[0119] The direction in which multiple tracks STR, which are multiple data tracks, are continuously written in a direction parallel to the radial direction d1, that is, the direction in which the previously written track STR overlaps with the direction in which the next track STR is written, is called the overlapping write direction or the recording travel direction. Figure 4 In the BAe shown, the overlapping write direction d5 is the inward direction, but the overlapping write direction can also be the outward direction.

[0120] For example, the overlapping write direction applied to multiple bands BA (multiple partitions Z) located on the outer periphery of a position beyond a specific radius position can be opposite to the overlapping write direction applied to multiple bands BA (multiple partitions Z) located on the inner periphery of a position beyond the aforementioned specific radius position.

[0121] The BAe has multiple tracks STR, including tracks STRe, STRe+1, and STRe+2. Tracks STRe, STRe+1, and STRe+2 are written sequentially in the overlapping write direction d5 according to their recording order. Among tracks STRe, STRe+1, and STRe+2, track STRe corresponds to the track where data is written first, and track STRe+2 corresponds to the track where data is written last.

[0122] Track STRE, without overlapping writes to other tracks, has a track center (STCe) at the center of radial direction d1. Track STRE+1, without overlapping writes to other tracks, has a track center (STCe+1) at the center of radial direction d1. Track STRE+2, without overlapping writes to other tracks, has a track center (STCe+2) at the center of radial direction d1.

[0123] exist Figure 4 In the example shown, tracks STRE, STRE+1, and STRE+2 are written using a pitch (track spacing) STP. The track center line STCe of track STRE is separated from the track center line STCe+1 of track STRE+1 by a pitch STP in the radial direction d1. The track center line STCe+1 of track STRE+1 is separated from the track center line STCe+2 of track STRE+2 by a pitch STP in the radial direction d1. Tracks STRE through STRE+2 can also be written using different pitches.

[0124] The radial width d1 of the region in track STR that was not overwritten with track STR+1 is the same as the radial width d1 of the region in track STR+1 that was not overwritten with track STR+2. Alternatively, the radial width d1 of the region in track STR that was not overwritten with track STR+1 can be different from the radial width d1 of the region in track STR+1 that was not overwritten with track STR+2.

[0125] exist Figure 4 For ease of explanation, each track STR is shown as rectangular, but in reality, each track STR is curved along the circumferential direction. Alternatively, each track STR can also be wavy, varying in the radial direction d1 while extending circumferentially. Furthermore, in... Figure 4 In this context, overlapping writes can be performed on 3-track STRs, but overlapping writes can also be performed on 2-track STRs, and overlapping writes can also be performed on more than 3-track STRs.

[0126] The write processing unit 62 can select a watt-type recorder that writes data overlappingly to multiple tracks STR in the overlapping write direction d5, causing the write head WHD to perform data writing to each track BA. Figure 4 In the example shown, the write processing unit 62 sequentially records watts of data onto tracks STRe to STRe+2 in the inward direction (overlapping write direction d5) with a spacing STP in the tape BAe. The user data area U is the area where data is written in watt-based recording, thus enabling an increase in the recording density of the user data area U.

[0127] The write processing unit 62 writes to track STR+1 in the inward direction of track STR with a spacing STP, thereby overlapping the write operation on a portion of the inner periphery of track STR. The write processing unit 62 also writes to track STR+2 in the inward direction of track STR+1 with a spacing STP, thereby overlapping the write operation on a portion of the inner periphery of track STR+1.

[0128] Figure 5 It is shown Figure 3 The diagram shows the three tracks (CTR) of the media cache M on disk DK, which performs normal recording processing, and the write head (WHD). Media cache M and Figure 3 The system area S shown is the normal recording area. Random data writing is permitted in both the media cache M and the system area S; that is, normal recording is allowed.

[0129] like Figure 5 As shown, the media cache M has multiple tracks CTR, including tracks CTRe, CTRe+1, and CTRe+2. These multiple tracks CTR are data tracks. For example, tracks CTRe, CTRe+1, and CTRe+2 have the same width (track width) in the radial direction d1. However, the track widths of tracks CTRe through CTRe+2 can also be different from each other.

[0130] Track CTRe has a track centerline CTCe at its center in the radial direction d1, track CTRe+1 has a track centerline CTCe+1 at its center in the radial direction d1, and track CTRe+2 has a track centerline CTCe+2 at its center in the radial direction d1. Figure 5 In the example shown, tracks CTRe, CTRe+1, and CTRe+2 are written using a spacing (typically recorded as track spacing) CTP. The track center line CTCe of track CTRe is separated from the track center line CTCe+1 of track CTRe by a spacing CTP. The track center line CTCe+1 of track CTRe+1 is separated from the track center line CTCe+2 of track CTRe+2 by a spacing CTP.

[0131] Tracks CTRe and CTRe+1 are separated by gap GP. Tracks CTRe+1 and CTRe+2 are separated by gap GP. Furthermore, tracks CTRe to CTRe+2 can also be written to at different intervals. Figure 5 For ease of explanation, each track CTR is shown as rectangular, but in reality, each track CTR is curved along the circumferential direction. Alternatively, each track CTR can also be wavy, varying in the radial direction d1 while extending along the circumferential direction.

[0132] The write processing unit 62 can perform write processing on a typical recording type that writes data to multiple tracks CTR at intervals along the radial direction d1 of the disk DK. Figure 5 In the example shown, the write processing unit 62 positions the write head WHD at the track center line CTCe in a predetermined area of ​​the disk DK and performs normal recording on the track CTRe or a predetermined sector of the track CTRe.

[0133] The write processing unit 62 positions the write head WHD at track center line CTCe+1, which is separated from track center line CTCe by distance CTP in the inward direction from track center line CTCe of track CTRe, and performs normal recording on track CTRe+1 or a predetermined sector of track CTRe+1. The write processing unit 62 positions the write head WHD at track center line CTCe+2, which is separated from track center line CTCe+1 by distance CTP in the inward direction from track center line CTCe+1 of track CTRe+1, and performs normal recording on track CTRe+2 or a predetermined sector of track CTRe+2.

[0134] The write processing unit 62 can perform normal recording on tracks CTRe, CTRe+1 and CTRe+2 sequentially or randomly on predetermined sectors of track CTRe, track CTRe+1 and track CTRe+2 in a predetermined area of ​​disk DK.

[0135] Figure 6 This is a schematic diagram illustrating an example of data write processing on a disk DK. Tracks STR and CTR are the data tracks, respectively. Figure 6 As shown, the user data area U has bands BAa, BAb, and Bac. Bands BAa, BAb, and Bac belong to the same partition Ze. Within partition Ze, bands BAa, BAb, and Bac are intermittently (discontinuously) arranged in the overlapping write direction according to their recording order.

[0136] BAa and BAb are adjacent in the radial direction d1, and BAb and BAc are adjacent in the radial direction d1.

[0137] Band BAa includes tracks STRa0, STRa1, STRa2, ..., STRa(x-3), STRa(x-2), and STRa(x-1), totaling x tracks. Tracks STRa0 to STRa(x-1) are recorded in the overlapping write direction d5 according to their recording order. In band BAa, track STRa0 corresponds to the first track where data is written, and track STRa(x-1) corresponds to the last track where data is written.

[0138] The tape BAb includes tracks STRb0, STRb1, STRb2, ..., STRb(x-3), STRb(x-2), and STRb(x-1), totaling x tracks. Tracks STRb0 to STRb(x-1) are recorded in the overlapping write direction d5 according to their recording order. In the tape BAb, track STRb0 corresponds to the first track where data is written, and track STRb(x-1) corresponds to the last track where data is written.

[0139] The tape BAc comprises x tracks: STRc0, STRc1, STRc2, ..., STRc(x-3), STRc(x-2), and STRc(x-1). Tracks STRc0 to STRc(x-1) are recorded in the overlapping write direction d5 according to their recording order. In the tape BAc, track STRc0 corresponds to the first track where data is written, and track STRc(x-1) corresponds to the last track where data is written.

[0140] Each band BA belonging to the same partition Z has the same number of tracks STR. For example, each band BA belonging to partition Ze has the same number of tracks STR. In other words, the number of tracks STR in each band BA is fixed within each partition Z. In this example, each band BA belonging to partition Ze has x tracks STR.

[0141] exist Figure 6 The image shows tracks CTR(x-2) and CTR(x-1). Figure 6 In this process, tracks CTR(x-2) and CTR(x-1) are normally recorded in the media cache M or system area S. Tracks CTR(x-2) and CTR(x-1) are adjacent in the radial direction d1.

[0142] Figure 7 It is shown Figure 6 The diagram shows two bands BAa and BAb and one guard band GB in the user data area U. (See diagram.) Figure 7 As shown, in the watt recording mode, unlike the usual recording mode, the MPU60 manages the track groups (groups) of the user data area U in units called watts, based on the feature of overlapping writing of a portion of the track STR.

[0143] A guard band (GB) is typically provided between adjacent bands (BA) in the radial direction d1. The guard band (GB) includes a guard track (GTR). Alternatively, unlike this embodiment, the guard band (GB) may include multiple guard tracks (GTR). The guard band (GB) serves to suppress interference between adjacent bands (BA). With the guard band (GB), watt-level recording can be performed on a unit of 1 band (BA). Furthermore, the guard band (GB) allows for the separation of areas (BA) written sequentially.

[0144] For example, the track center lines STCa(x-3) of track STa(x-3), STCa(x-2) of track STa(x-2), STCa(x-1) of track STa(x-1), GTC of track GTR, STCb0 of track STRb0, STCb1 of track STRb1, and STCb2 of track STRb2 are arranged at equal intervals in the overlapping write direction d5.

[0145] Besides the guard band (GB), the recording capacity of each band (BA) in the user data area U is usually predetermined based on user requirements. The MPU60 can record the same amount of data in each band BA. Typically, the recording capacity of each band BA is 128 MiB or 256 MiB.

[0146] Figure 8 It is shown Figure 6 The diagram shows three sectors SCe, SC(e+1), and SC(e+2) in track STRa0 with BAa. Figure 8 As shown, each track STR has multiple sectors SC. Track STRa1 has multiple sectors SC, including sectors SCe, SC(e+1), and SC(e+2).

[0147] When sector SC(e+1) of multiple sectors SC of track STRa0 is taken as the nth sector, sector SC(e+2) is the (n+1)th sector following sector SC(e+1) in the travel direction d2, and sector SCe is the (n-1)th sector located before sector SC(e+1) in the travel direction d2. Tracks STR belonging to the same partition Z have the same number of sectors SC. In this embodiment, each track STR belonging to partition Ze has y sectors SC.

[0148] Each sector SC has a length Ls in the circumferential direction of disk DK. Sometimes, each sector SC is also called a split sector, which is divided by servo sectors SV. In this case, the length of sector SC may not be Ls.

[0149] The write head (WHD) is an energy-assisted recording head for performing energy-assisted magnetic recording (EAMR). In this embodiment, the write head (WHD) is configured to utilize energy other than magnetism, but it is not limited to this; the write head (WHD) may also be a magnetic head that is not configured to perform energy-assisted recording.

[0150] Figure 9 It is shown Figure 7 The diagram shown, with two bands BAa and Bab and one guard band GB, is used to illustrate multiple object sector RSCs and multiple unused sector VSCs.

[0151] exist Figure 9 For ease of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumference. Furthermore, although multiple track STRs are arranged non-overlapping in the overlapped write direction d5, they are actually arranged overlappingly in the overlapped write direction d5. Additionally, dotted patterns are used to annotate the target sector RSC in the figure. Unused sectors VSC are represented without patterns.

[0152] like Figure 9 As shown, the track number with BAa is set to "a", and the track number with BAb is set to "b". The track numbers for each BA are set to "0" to "x-1". The sector numbers for each track STR are set to "0" to "y-1". Hereinafter, the following designation "SC (track number, sector number)" is sometimes used to identify each sector SC with BA.

[0153] In this embodiment, band BAa is the band adjacent to band BAb, and is located upstream of band BAb in the overlapping write direction d5.

[0154] Each track STR with BAa includes G object sector RSCs (more than one object sector RSC) with valid data written to it. For example, track STa0 has y object sector RSCs (G = y). All sectors SC of track STa0 are object sector RSCs. Track STa(x-1) has 5 object sector RSCs (G = 5). The remaining sectors SC of track STa(x-1) are unused sectors VSCs that have not been written with valid data.

[0155] Based on the above, the number of target sector RSCs in track STa0 is different from the number of target sector RSCs in track STa(x-1).

[0156] Within each band BA of partition Ze, all sectors SC of track x-1 from 0 to x-2 are object sectors RSC (record sectors) with valid data written to them, and are also record sectors USC. Within track x-1 of each band BA of partition Ze, the five sectors SC from 0 to 4 are object sectors RSC (record sectors) and are also record sectors USC. On the other hand, within track x-1 of track STR, the remaining sectors SC from 5 to y-1 are unused sectors VSC (unused sectors) without valid data written to them.

[0157] Figure 10 This diagram illustrates an example of tracks STR0 and STR1, assuming disk device 1 does not have the function of performing error correction on track TR. It is a diagram illustrating the write processing of tracks STR0 and STR1, a diagram illustrating the state where write processing of track STR1 continues until the error correction per sector on track STR0 reaches its limit, and a diagram graphically representing the change in Bit Error Rate (BER) relative to track STR0 and the change in BER relative to Position Error (PE). In use... Figure 10 The description states that disk device 1 does not have... Figure 1 The error correction section 64 will be explained. Additionally, in Figure 10 For ease of explanation, the first magnetic track STR0, etc., are also depicted as a straight line in the circumferential direction.

[0158] like Figure 10 As shown, in the recording layer L, multiple tracks STR are adjacent in the radial direction d1. Track 1 STR0 and track 2 STR1 are data tracks and are adjacent to each other. All sectors SC of track 1 STR0 and all sectors (data sectors) SC of track 2 STR1 are object sectors RSC. Write processing to track 1 STR0 is ideally performed without positioning error PE (PE≒0 or PE=0).

[0159] When disk device 1 is subjected to external vibrations or other influences during write processing, a positioning error PE will occur during the positioning of the write head WHD. The positioning error PE is the offset of the write head WHD from the target position in the radial direction d1. By setting the track margin TM, the allowable range that ensures data can be read from adjacent tracks can be determined.

[0160] For example, during a write operation on track 2 STR1, when the positioning error PE exceeds the track margin TM, if the target sectors RSCe, RSC(e+1), and RSC(e+2) of track 1 STR0 are adjacent to the write head WHD in the radial direction d1, it is determined (presumably) that the data in the target sectors RSCe, RSC(e+1), and RSC(e+2) of track 1 STR0 is corrupted. Although a lower BER is better, this will cause the BER of the data in the target sectors RSCe, RSC(e+1), and RSC(e+2) of track 1 STR0 to exceed the threshold BERTH. Furthermore, according to... Figure 10 As shown in the chart on the right, the larger the positioning error PE, the greater the adverse effect of ATI (Adjacent Track Interference), which causes the BER of the data of track STR0, which is excessively affected by ATI, to become too high.

[0161] Therefore, in track STR0, target sectors RSCe, RSC(e+1), and RSC(e+2) are identified as damaged target sectors CSC1, CSC2, and CSC3, respectively. This will result in a deterioration in the signal quality obtained when reading data from damaged target sectors CSC1 to CSC3, or the data in damaged target sectors CSC1 to CSC3 being erased.

[0162] In use Figure 10 In the illustrated example, disk device 1 does not have the function of performing track-by-track error correction on the data of track TR. Here, track-by-track error correction is also referred to as track-by-track error correction, track ECC (Error Checking and Correcting), etc. Therefore, the target sector RSCe, target sector RSC(e+1), and target sector RSC(e+2) remain as damaged target sector CSC1, damaged target sector CSC2, and damaged target sector CSC3, respectively.

[0163] Here, in Figure 10 In the previous section, it was explained that all target sectors RSC, assuming track TR, share a common track margin TM. This will be discussed later. Figure 11 and Figure 12 The description also assumes that all target sectors RSC of track TR share a common track margin TM. However, the above setting of track margin TM is an example, and the track margin TM can also be made different on a per-target sector RSC basis.

[0164] Figure 11This diagram illustrates an example of tracks STR0 and STR1, assuming that disk device 1 does not have the function of performing track-by-track error correction on data in track TR. It is a diagram illustrating the write processing of tracks STR0 and STR1. It is a diagram illustrating the state where the judgment value is set to a (strict) write track deviation limit WOS smaller than the track margin TM, and the write processing of track STR1 ends when the positioning error PE is detected to exceed the reference radius position PO. It is a graph showing the changes in BER relative to track STR0 and the changes in BER relative to the positioning error PE, respectively. Figure 11 For ease of explanation, the first magnetic track STR0, etc., are also depicted as a straight line along the circumference. When using... Figure 11 The description states that disk device 1 does not have... Figure 1 The error correction section 64 will be explained.

[0165] like Figure 11 As shown, track STR0 and track STR1 are data tracks, and all sectors SC of track STR0 and all sectors (data sectors) SC of track STR1 are the target sectors RSC. Write operations on track STR0 are ideally performed without a positioning error PE (PE ≒ 0 or PE = 0). From track STR1, track STR0 is located in the first direction Da, which is parallel to the radial direction d1.

[0166] The write processing unit 62 is capable of selecting a watt-type recorder that writes data of the second track STR1 on the data of the first track STR0 in an overlapping write direction d5 opposite to the first direction Da.

[0167] To prevent or suppress write operations when the positioning error PE exceeds the track margin TM, the disk device 1 has a write track offset limit (WOS). The reference radius position PO is offset from the track center line STC1 of track 2 STR1 in the first direction Da by the write track offset limit WOS. During data writing to track 2 STR1, if it is determined that the positioning error PE exceeds the reference radius position PO, the data writing to track 2 STR1 can be stopped. The remaining object sectors RSC of the multiple object sectors RSC of track 2 STR1 that are abandoned for data writing become free sectors ESC without written data. By avoiding the situation where the positioning error PE exceeds the track margin TM, it is possible to prevent the generation of corrupt object sectors CSC on track 1 STR0.

[0168] In addition, the track STR has servo sectors in addition to the sector SC as the data sector. In the track STR, usually, the data sectors and the servo sectors are alternately arranged. The head HD (read head RHD) can derive the positioning error PE together with the servo sectors. Therefore, usually, the positioning error PE is information obtained intermittently.

[0169] In order to avoid PE > TM, it is necessary to set the write track deviation limit WOS in such a way that WOS ≤ TM. In order to avoid the situation of PE > TM, it is preferable to set the write track deviation limit WOS in such a way that WOS < TM. Thereby, it is possible to abort the write process for the second track STR1 before the positioning error PE exceeds the track margin TM, and it is possible to avoid the situation where the quality of the data in the first track STR0 deteriorates.

[0170] However, it should be noted that the smaller the write track deviation limit WOS is set, the easier the write process is to abort, which will lead to a reduction in the write performance of the disk device 1. In addition, in the disk device 1 that does not have the function of performing error correction on a track-by-track basis, in the case of aborting the write process for the second track STR1, a write retry process of waiting for the disk DK to rotate until PE ≤ WOS and then restarting the write process for the second track STR1 is executed. In the write retry process, the free sector ESC of the second track STR1 can be changed to the recording sector USC, so it is possible to avoid the situation where the utilization efficiency of the second track STR1 remains low.

[0171] Here, in Figure 11 it has been described that all the target sectors RSC of the track TR have a common write track deviation limit WOS. In the description of Figure 12 described later, it is also described that all the target sectors RSC of the track TR have a common write track deviation limit WOS. However, the setting of the above write track deviation limit WOS is an example, and the write track deviation limit WOS can also be different for each target sector RSC.

[0172] Figure 12 is a schematic diagram showing an example of the first track STR0 and the second track STR1 of the disk device 1 having the function of performing error correction on a track-by-track basis for the data of the track TR, is a diagram for explaining the write process for the first track STR0 and the second track STR1, is a diagram for explaining the state where the determination value is set to be larger (looser) than the track margin TM and the write process for the second track STR1 is continued until the track-by-track error correction for the first track STR0 reaches the limit, and is a diagram showing the change of BER with respect to the first track STR0 and the change of BER with respect to the positioning error PE in a graph respectively. In Figure 12For ease of explanation, the first magnetic track STR0, etc., are also depicted as a straight line in the circumferential direction.

[0173] like Figure 12 As shown, the write operation for track STR0 is ideally performed without a positioning error PE (PE≒0 or PE=0).

[0174] The disk drive 1 includes an error correction unit 64. When a corrupted target sector (CSC) is generated on track ST, the read processing unit 63, together with the head amplifier IC 130, can detect this situation, and the error correction unit 64 can perform error correction processing to recover the data from the corrupted target sector CSC. For example, if a corrupted target sector CSC is generated on track STR0, the error correction unit 64 can recover the data from the corrupted target sector CSC based on the data from multiple target sector RSCs and the parity sector data on track STR0.

[0175] The parity sector described above is generated based on data from multiple target sector RSCs of track STR0, and can be set within a portion of the multiple target sector RSCs of track STR0. For example, one or two target sector RSCs in track STR0 can be used as parity sectors. However, the parity sector described above can also be set on track TR other than track STR0. Alternatively, the parity sector can also be set in memory outside the disk (e.g., non-volatile memory 90).

[0176] As described above, even if a corrupted sector CSC is generated on track STR0, the error correction unit 64 can perform error correction processing to recover the data in the corrupted sector CSC, thus allowing the corrupted sector CSC to be generated on track STR0. In the disk device 1 equipped with the error correction unit 64, the write track can be set to deviate from the limit WOS in a manner that makes WOS≥TM, making it difficult to terminate the write process and suppressing the degradation of the write performance of the disk device 1.

[0177] Furthermore, it should be noted that the number of damaged sectors that the error correction unit 64 can perform error correction on a track-by-track basis is limited to the track TR. For example, if the number of damaged sectors CSCs on track STR0 exceeds the limit (e.g., 12), the error correction unit 64 may have difficulty recovering the data of all damaged sectors CSCs.

[0178] Figure 13It is a table showing the presence or absence of ECC track in the first to third modes of the first and second write operations, the function name of the control DOL, the handling content when the positioning error PE exceeds the reference radius position PO, the setting of the prediction upper limit threshold, and the setting of the prediction excess amount.

[0179] like Figure 13 , Figure 11 and Figure 1 As shown, assuming that disk device 1 does not have ECC functionality, disk device 1 can perform the first write operation. Control DOL (Drift-Off) The function name for Level is DDOL (Dynamic Drift-Off Level). The first write action corresponds to using... Figure 11 The writing action is shown.

[0180] If, during the first write operation of writing to track STR1, the positioning error PE exceeds the reference radius position PO, the write operation to track STR1 is aborted before the positioning error PE exceeds the track margin TM. Afterwards, a write retry process is performed, waiting for disk DK to rotate until PE ≤ WOS, and then resuming the write operation to track STR1.

[0181] When disk device 1 uses the first write operation, write retries, such as waiting for disk DK rotation, may occur frequently, making it difficult to improve the write performance of disk device 1. Therefore, to improve the write performance of disk device 1, disk device 1 using the second write operation has track ECC functionality. In disk device 1 using the second write operation, the function controlling DOL is called iDDOL (intelligence dynamic drift-off level).

[0182] It can allow a certain number of damaged object sectors (CSCs) to be generated in the track STR, which can increase TPI (Track Per Inch).

[0183] (Second method of the second write action) (Prediction upper limit threshold: constant)

[0184] Next, we will explain the second method for the second write operation. Here, the upper limit threshold for prediction is set to a constant.

[0185] like Figure 13 , Figure 1 and Figure 12 As shown, the error correction unit 64 can perform error correction on the data of one or more corrupted object sectors CSC in the multiple object sectors RSC of the first track STR0 that are determined to have data corruption.

[0186] Here, we focus on the first write period, which is the period after the write processing unit 62 performs write processing on the multiple target sectors RSC of the first track STR0, and the period during which write processing is performed on the multiple target sectors RSC of the second track STR1.

[0187] During the first write operation, the read processing unit 63 performs a first seek operation to move the read head RHD a first distance, bringing the write head WHD towards the second track STR1. For example, if a write operation to the second track STR1 is performed after a write operation to the first track STR0, the first distance is equivalent to moving the read head RHD by one track.

[0188] The adjustment unit 65 derives a first predicted overshoot, which is the amount by which the position of the write head WHD exceeds the reference radius position PO in the first direction Da during the first write operation. The first predicted overshoot is an amount that varies based on the distance the read head RHD seeks (seek distance). The adjustment unit 65 can adjust the first predicted overshoot and other predicted overshoots based on the seek distance.

[0189] For example, when the first distance is equivalent to the amount by which the read head RHD moves by one track, the adjustment unit 65 adjusts the prediction overshoot to the minimum, i.e., the minimum prediction overshoot.

[0190] Furthermore, the adjustment unit 65 derives a prediction upper limit threshold representing the limit of the executable range for error correction of the first track STR0. The prediction upper limit threshold is a constant.

[0191] Whenever data is written to each target sector RSC of track STR1, the correction limit prediction unit 66 measures the measured excess amount by which the position of the write head WHD exceeds the reference radius position PO in the first direction Da, updates the accumulated measured excess amount as the cumulative measured excess amount, and calculates the first cumulative predicted excess amount by adding the first predicted excess amount to the accumulated measured excess amount.

[0192] Here, the cumulative measured excess represents the expected amount of data corruption on track STR0 at the point in time from the execution of write processing up to the RSC of the target sector opposite to the write head WHD in track STR1.

[0193] The first cumulative prediction overshoot represents the expected amount of data corruption in track STR0 under the assumption that the write head WHD is facing the next target sector RSC along the travel direction d2 and a write operation is performed on that target sector RSC.

[0194] If the determination unit 67 determines that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit 62 can continue to perform write processing on the second track STR1.

[0195] In addition, the judgment unit 67 can cause the write processing unit 62 to stop (or end) the write processing of the second track STR1 if it determines that the first cumulative prediction exceeds the prediction upper limit threshold.

[0196] As described above, in the second mode of the second write operation, the prediction overshoot can be adjusted according to the seek distance. For example, consider the case where the first distance is equivalent to the distance that moves the read head RHD by one track. In the second mode of the second write operation, the adjustment unit 65 adjusts the prediction overshoot to the minimum, i.e., the minimum prediction overshoot. On the other hand, in the first mode of the second write operation, the adjustment unit 65 adjusts the prediction overshoot to the maximum, i.e., the maximum prediction overshoot. This is because, in the first mode of the second write operation, the prediction overshoot is always fixed at the maximum prediction overshoot.

[0197] Compared to the first method using a second write operation, the second method of the second write operation does not cause the cumulative prediction overshoot to be too large. Therefore, it can reduce the frequency of aborting (or ending) the write process on track STR1. Furthermore, it can reduce the frequency of initiating the Partial Track Slip (PTS) to transfer the remaining data that could not be written to track STR1 when the write process has ended. The second method of the second write operation can help improve the write performance of disk device 1.

[0198] Here, we focus on the nth object sector RSCn of track STR1.

[0199] The multiple target sectors RSC of track STR1 include the nth target sector RSCn and the (n+1)th target sector RSC(n+1) following the nth target sector RSCn in the direction of travel d2.

[0200] During the first write operation, the write processing unit 62 performs write processing up to the nth target sector RSCn of track STR1. The correction limit prediction unit 66 measures the measured excess amount and updates the cumulative measured excess amount. Furthermore, it adds the first predicted excess amount to the cumulative measured excess amount to calculate the first cumulative predicted excess amount. The first predicted excess amount is the amount by which the position of the write head WHD exceeds the reference radius position PO in the first direction Da, assuming data is written to the (n+1)th target sector RSC(n+1) during the first write operation.

[0201] If the determination unit 67 determines that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit 62 can continue to perform write processing on the (n+1)th object sector RSC(n+1) of the second track STR1.

[0202] In addition, the judgment unit 67 can cause the write processing unit 62 to stop (or end) the write processing of the (n+1)th target sector RSC(n+1) of the second track STR1 if it determines that the first cumulative prediction exceeds the prediction upper limit threshold.

[0203] Next, we will focus on the first prediction over-quantity and other prediction over-quantities.

[0204] When the first distance is less than or equal to the distance by which the read head RHD moves one track in the radial direction d1, the adjustment unit 65 can adjust the first prediction overshoot (prediction overshoot) to the minimum, i.e., the minimum prediction overshoot.

[0205] On the other hand, when the first distance is greater than or equal to the distance by which the read head RHD moves two tracks in the radial direction d1, the adjustment unit 65 can adjust the first prediction overage (prediction overage) to an amount greater than the minimum prediction overage.

[0206] Furthermore, since a technique to reduce head shaking is used to perform the seek operation, the aforementioned predicted overshoot is not a value proportional to the seek distance. However, it is anticipated that head HD shaking increases when the seek distance is more than two tracks, compared to cases where the seek distance is less than one track. Therefore, when the seek distance is more than two tracks, the predicted overshoot is adjusted to be an amount greater than the minimum predicted overshoot. Figure 14 ).also, Figure 14 The value of the vertical axis is an example, and various deformations can be performed.

[0207] Here, we will explain the path-finding motion that can reduce head shaking.

[0208] The seek process performed by the read processing unit 63 includes an acceleration period as the initial period and a deceleration period as the final period. During the acceleration period, the read processing unit 63 gradually increases the speed of the read head RHD in the first seek direction while seeking. During the deceleration period, the read processing unit 63 gradually decreases the speed of the read head RHD in the first seek direction while seeking.

[0209] When the read head RHD seeks from the outer periphery to the second track STR1, the first seeking direction is the inward direction; when the read head RHD seeks from the inner periphery to the second track STR1, the first seeking direction is the outward direction.

[0210] Instead of making the read head RHD seek at a constant speed, the read head RHD seeks by gradually accelerating and decelerating (ease-in-out). Because this suppresses abrupt changes in the speed of the read head RHD during seek, it reduces the risk of resonance at the resonant frequency of the system. This seek operation can also be used in conjunction with the second method of the second write operation, thereby helping to improve the write performance of the disk device 1.

[0211] Next, we will explain the case where a seek operation is interrupted during the write process for track STR1 of track 2. Here, we will focus on the nth object sector RSCn.

[0212] When write processing is performed during the first write period up to the nth target sector RSCn of track STR1, and the read head RHD seeks after the first write period, and then write processing is restarted during the second write period from the (n+1)th target sector RSC(n+1) of track STR1, the write processing unit 62 and the correction limit prediction unit 66 perform the following processing during the first write period.

[0213] The write processing unit 62 performs write processing up to the nth object sector RSCn of track STR1.

[0214] The correction limit prediction unit 66 measures the measured excess amount and updates the cumulative measured excess amount. Furthermore, it adds the first predicted excess amount to the cumulative measured excess amount to calculate the first cumulative predicted excess amount. The first predicted excess amount is the amount by which the position of the write head WHD exceeds the reference radius position PO in the first direction Da, assuming data is written to the (n+1)th object sector RSC(n+1) during the first write operation.

[0215] During the second write operation, the read processing unit 63, the adjustment unit 65, the correction limit prediction unit 66, and the judgment unit 67 perform the following processing.

[0216] The read processing unit 63 performs a second seek process to make the read head RHD seek the track, moves the read head RHD a second distance, and makes the write head WHD face the second track STR1 again.

[0217] The adjustment unit 65 re-derives a second predicted excess amount, which is the amount by which the position of the write head WHD during the second write operation exceeds the reference radius position PO in the first direction Da. The second predicted excess amount is the amount corresponding to the second distance mentioned above.

[0218] The correction limit prediction unit 66 recalculates the second cumulative predicted excess by adding the second predicted excess to the cumulative measured excess. The second predicted excess is the amount by which the position of the write head WHD exceeds the reference radius position PO in the first direction Da, assuming that data is written to the (n+1)th object sector RSC(n+1) during the second write.

[0219] If the determination unit 67 determines that the second cumulative prediction exceeds the prediction upper limit threshold, it can cause the write processing unit 62 to start writing processing on the (n+1)th object sector RSC(n+1) of the second track STR1 again.

[0220] In addition, the judgment unit 67 can cause the write processing unit 62 to stop (or end) the write processing of the (n+1)th target sector RSC(n+1) of the second track STR1 if it determines that the second cumulative prediction exceeds the prediction upper limit threshold.

[0221] As described above, when disk device 1 adopts the second method of the second write operation, the prediction overshoot can be adjusted, thereby improving the write performance of disk device 1.

[0222] When the seek distance is two tracks or more, the prediction overshoot is adjusted to be greater than the minimum prediction overshoot. Therefore, compared to cases where the seek distance is one track or less, the frequency of aborting (or ending) write processing on track 2 STR1 may increase. Furthermore, the frequency of initiating a PTS (Push-to-Swap) to transfer remaining data that could not be written to track 2 STR1 when write processing has ended may also increase.

[0223] Therefore, the disk device 1 using the third method of the second write operation can wait for the disk DK to rotate when the write processing of the second track STR1 is stopped, and adjust the predicted excess amount to a smaller amount.

[0224] (Third method of the second writing action) (Prediction upper limit threshold: constant)

[0225] Next, we will explain the third method for the second write operation. Here, the upper limit threshold for prediction is set to a constant.

[0226] During the first write operation, if the read processing unit 63 moves the read head RHD by a distance greater than the distance of moving two data tracks, and the adjustment unit 65 adjusts the first prediction overshoot by an amount greater than the minimum amount, and the judgment unit 67 determines that the first cumulative prediction overshoot exceeds the prediction upper limit threshold, the correction limit prediction unit 66 and the judgment unit 67 perform the following processing.

[0227] The correction limit prediction unit 66 then adds the aforementioned minimum prediction excess to the cumulative measured excess to calculate the minimum cumulative prediction excess.

[0228] When the determination unit 67 determines that the minimum cumulative prediction exceedance is below the prediction upper limit threshold, it controls the drive of the write processing unit 62 to stop the write processing of the second track STR1, maintains the position of the write head WHD in the radial direction d1, and switches to a write retry operation that waits for the disk DK to rotate before restarting the write processing. Therefore, compared with the second method of the second write operation, the frequency of PTS startup can be reduced, and the utilization efficiency of track STR can be improved.

[0229] In addition, the command processing latency increases when PTS is enabled compared to write retry actions. Therefore, having an option to switch to write retry actions is effective in improving write performance.

[0230] Furthermore, if the determination unit 67 determines that the minimum cumulative prediction overshoot exceeds the prediction upper limit threshold, it can cause the write processing unit 62 to terminate the write processing of track STR1 and transfer the remaining data that could not be written to track STR1 to a recording area other than track STR0 and track STR1. As a recording area other than track STR0 and track STR1, tracks such as track STR3, which is located in the overlapping write direction d5 and adjacent to track STR1 from track STR1, and tracks on disk DK can be included. The recording area other than track STR0 and track STR1 can also be the storage medium outside disk DK.

[0231] (Second method of the second writing action) (Prediction upper limit threshold: variable)

[0232] Next, another example of the second method of the second write action will be explained. Here, the prediction upper limit threshold is set as a variable. In addition, except as described here, the second method of the second write action with the prediction upper limit threshold set as a variable is the same as the second method of the second write action with the prediction upper limit threshold set as a constant.

[0233] like Figure 13 , Figure 1 and Figure 12 As shown, focusing on the first write period, the first write period is the period after the write processing unit 62 performs write processing on the multiple target sectors RSC of the first track STR0, and the period during which write processing is performed on the multiple target sectors RSC of the second track STR1.

[0234] During the first write operation, the read processing unit 63 performs the first seek process described above, causing the write head WHD to face the second track STR1.

[0235] The adjustment section 65 derives the first prediction exceeding the amount.

[0236] Furthermore, the adjustment unit 65 derives a prediction upper limit threshold representing the limit of the executable range for error correction of the first track STR0. The prediction upper limit threshold is a variable. The greater the various prediction overshoots, including the first prediction overshoot, the smaller the prediction upper limit threshold value.

[0237] Whenever data is written to each target sector RSC of track STR1, the correction limit prediction unit 66 calculates the first cumulative prediction overshoot.

[0238] If the determination unit 67 determines that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit 62 can continue to perform write processing on the second track STR1.

[0239] In addition, the judgment unit 67 can cause the write processing unit 62 to stop (or end) the write processing of the second track STR1 if it determines that the first cumulative prediction exceeds the prediction upper limit threshold.

[0240] As described above, in the second write operation where the prediction upper limit threshold is set as a variable, the prediction overshoot can be adjusted based on the seek distance. Furthermore, in the second write operation where the prediction upper limit threshold is set as a variable, the prediction upper limit threshold is a variable. For example, when the first distance is equivalent to the amount by which the read head RHD moves one track, the adjustment unit 65 can adjust the first prediction overshoot to a minimum (minimum prediction overshoot), adjust the first cumulative prediction overshoot to a minimum, and adjust the prediction upper limit threshold to a maximum (maximum prediction upper limit threshold). Since the setting makes it difficult for the first cumulative prediction overshoot to exceed the prediction upper limit threshold, writing to the second track STR1 can be easily continued.

[0241] On the other hand, when the first distance is equivalent to or greater than the amount by which the read head RHD moves two tracks, and the adjustment unit 65 adjusts the first prediction overshoot to the maximum (i.e., the maximum prediction overshoot) and the first cumulative prediction overshoot to the maximum, the adjustment unit 65 can adjust the prediction upper limit threshold to the minimum (i.e., the minimum prediction upper limit threshold). Since the setting makes it easy for the first cumulative prediction overshoot to exceed the prediction upper limit threshold, the write processing of the second track STR1 can be easily stopped (or ended).

[0242] Setting the upper limit threshold of the prediction as a variable in the second write operation can also help improve the write performance of disk device 1.

[0243] Next, we will focus on the first prediction overshoot and the prediction upper limit threshold.

[0244] When the first distance is less than the distance that causes the read head RHD to move one track in the radial direction d1, the adjustment unit 65 can adjust the first prediction overage (prediction overage) to the minimum, i.e., the minimum prediction overage, and adjust the prediction upper limit threshold to the maximum, i.e., the maximum prediction upper limit threshold.

[0245] On the other hand, when the first distance is greater than or equal to the distance by which the read head RHD moves two tracks in the radial direction d1, the adjustment unit 65 can adjust the first prediction overage (prediction overage) to an amount greater than the minimum prediction overage and adjust the prediction upper limit threshold to a value smaller than the maximum prediction upper limit threshold.

[0246] Next, we will explain the case where a seek operation is interrupted during the write process for track STR1 of track 2. Here, we will focus on the nth object sector RSCn.

[0247] When write processing is performed during the first write period up to the nth target sector RSCn of track STR1, and the read head RHD seeks after the first write period, and then write processing is restarted during the second write period from the (n+1)th target sector RSC(n+1) of track STR1, the write processing unit 62 and the correction limit prediction unit 66 perform the following processing during the first write period.

[0248] The write processing unit 62 performs write processing up to the nth object sector RSCn of track STR1.

[0249] The correction limit prediction unit 66 measures the measured excess amount, updates the cumulative measured excess amount, and calculates the first cumulative predicted excess amount by adding the first predicted excess amount to the cumulative measured excess amount.

[0250] During the second write operation, the read processing unit 63, the adjustment unit 65, the correction limit prediction unit 66, and the judgment unit 67 perform the following processing.

[0251] The read processing unit 63 performs the second seek process described above, so that the write head WHD faces the second track STR1 again.

[0252] Adjustment section 65 re-derives the above-mentioned second prediction exceeding the amount.

[0253] In addition, the adjustment unit 65 adjusts the upper limit threshold of the prediction to a value corresponding to the second prediction excess mentioned above.

[0254] The correction limit prediction unit 66 adds the second predicted excess to the cumulative measured excess and recalculates the second cumulative predicted excess.

[0255] If the determination unit 67 determines that the second cumulative prediction exceeds the prediction upper limit threshold, it can cause the write processing unit 62 to start writing processing on the (n+1)th object sector RSC(n+1) of the second track STR1 again.

[0256] In addition, the judgment unit 67 can cause the write processing unit 62 to stop (or end) the write processing of the (n+1)th target sector RSC(n+1) of the second track STR1 if it determines that the second cumulative prediction exceeds the prediction upper limit threshold.

[0257] Furthermore, the second method of the second write action, which sets the upper limit of the prediction threshold as a variable, can also perform the action of waiting for disk DK to rotate when the write processing of the second track STR1 is stopped, and adjust the prediction over-limit to a smaller amount.

[0258] (Third method of writing the second action) (Prediction upper limit threshold: variable)

[0259] Next, another example of the third method of the second write action will be explained. Here, the prediction upper limit threshold is set as a variable. In addition, except as described here, the third method of the second write action with the prediction upper limit threshold set as a variable is the same as the third method of the second write action with the prediction upper limit threshold set as a constant.

[0260] During the first write operation, if the read processing unit 63 moves the read head RHD by a distance greater than the distance of moving two data tracks, and the adjustment unit 65 adjusts the first prediction overshoot by an amount greater than the minimum amount, and the adjustment unit 65 adjusts the prediction upper limit threshold by a value smaller than the maximum prediction upper limit threshold, and the determination unit 67 determines that the first cumulative prediction overshoot exceeds the prediction upper limit threshold, the correction limit prediction unit 66 and the determination unit 67 perform the following processing.

[0261] The correction limit prediction unit 66 then adds the aforementioned minimum prediction excess to the cumulative measured excess to calculate the minimum cumulative prediction excess.

[0262] When the determination unit 67 determines that the minimum cumulative prediction exceedance is below the prediction upper limit threshold, it controls the drive of the write processing unit 62 to stop the write processing of the second track STR1, maintains the position of the write head WHD in the radial direction d1, and switches to a write retry operation that waits for the disk DK to rotate before restarting the write processing. This reduces the startup frequency of the PTS and improves the utilization efficiency of the track STR.

[0263] In addition, if the determination unit 67 determines that the minimum cumulative prediction over-limit exceeds the prediction upper limit threshold, the write processing unit 62 can end the write processing of the second track STR1 and transfer the remaining data that could not be written to the second track STR1 to a recording area other than the first track STR0 and the second track STR1.

[0264] (Examples of the second and third methods for the second write action) (Prediction upper limit threshold: constant)

[0265] Next, examples of the second and third methods for the second write operation will be provided. Here, the upper limit threshold for prediction is set to a constant. Figure 15 The graph shows the changes in positioning error PE, cumulative excess, and cumulative prediction excess when write processing is performed on track STR1 in the second and third modes of the second write operation. It also shows the case where the prediction upper limit threshold is constant.

[0266] like Figure 15 As shown, multiple object sectors RSC (Data Region DTR) and multiple servo sectors SSC (Servo Region SV) are arranged in a circumferential direction. Whenever the read head RHD passes through a servo sector SSC, the position of the head HD in the radial direction d1 can be corrected. This is effective when the head HD becomes vibrate due to seek operations, etc. However, the proportion (size) of the servo sector SSC in the track STR is smaller than that of the object sector RSC in the track STR. Therefore, it is difficult to sufficiently correct the position of the head HD in the radial direction d1.

[0267] Therefore, when performing write processing on multiple target sector RSCs of track STR1, the positioning error PE may sometimes exceed the reference radius position PO multiple times. The correction limit prediction unit 66 calculates the cumulative prediction overshoot, and the management unit 68 predicts the number of damaged target sector CSCs of track STR0. That is, during the write process to track STR1, whenever the positioning error PE exceeds the reference radius position PO, the management unit 68 can detect that a damaged target sector CSC has been generated in track STR0, and manage the cumulative number of damaged target sector CSCs in track STR0.

[0268] exist Figure 15In this example, we focus on the time point when the write processing unit 62 performs write processing up to the nth object sector RSCn of track 2 STR1. The management unit 68 can determine that 10 corrupt object sectors CSC have been generated on track 1 STR0. Here, we assume that the error correction unit 64 can perform error correction up to 12 corrupt object sector CSCs on track 1 STR0. In this case, the determination unit 67 can determine that it is permissible for 10 corrupt object sector CSCs to be generated on track 1 STR0, and that the generation of up to 2 new corrupt object sector CSCs is also permissible.

[0269] Furthermore, the judgment unit 67 can determine whether the cumulative prediction overshoot exceeds the prediction upper limit threshold. Figure 15 In the example, the first prediction overshoot and the first cumulative prediction overshoot correspond to the case where the seek distance is less than one track. Figure 14 For example, in the case of performing a write operation to track STR1 after writing to track STR0. The first prediction overshoot is the minimum prediction overshoot, and the first cumulative prediction overshoot is the minimum cumulative prediction overshoot. The cumulative prediction overshoot is below the upper prediction threshold, therefore, the determination unit 67 can determine that the write operation to track STR1 can continue.

[0270] On the other hand, Figure 15 In the example, the second prediction overshoot and the second cumulative prediction overshoot are equivalent to a seek distance of 2 tracks or more, and the head HD shaking becomes the maximum. Figure 14 For example, during the first write operation, write processing is performed until the nth target sector RSCn of track STR1 is reached, then a seek operation is performed, and during the second write operation, an attempt is made to restart write processing from the (n+1)th target sector RSC(n+1) of track STR1. The second prediction overshoot is the maximum prediction overshoot, and the second cumulative prediction overshoot is the maximum cumulative prediction overshoot. The cumulative prediction overshoot exceeds the prediction upper limit threshold, therefore, the determination unit 67 can determine that write processing to track STR1 needs to be aborted (or terminated).

[0271] (Examples of the second and third methods of the second writing action) (Prediction upper limit threshold: variable)

[0272] Next, examples of the second and third methods for the second write action will be provided. Here, the upper limit threshold for prediction will be set as a variable. Figure 16 The graph shows the changes in positioning error PE, cumulative excess, and cumulative prediction excess when write processing is performed on track STR1 in the second and third modes of the second write operation. It also shows the case where the prediction upper limit threshold is a variable.

[0273] like Figure 16 As shown, firstly, focusing on the time point from when the write processing unit 62 performs write processing up to the nth target sector RSCn of track 2 STR1, the management unit 68 can determine that 10 corrupted target sectors CSC have been generated on track 1 STR0. In this case, the determination unit 67 can determine that it is permissible for 10 corrupted target sectors CSC to be generated on track 1 STR0, and that the generation of up to 2 new corrupted target sectors CSC can also be permitted.

[0274] Furthermore, the judgment unit 67 can determine whether the cumulative prediction overshoot exceeds the prediction upper limit threshold. Figure 16 In the example, the first prediction over-quantity is equivalent to the amount less than one track distance. Figure 14 For example, in the case of performing a write operation to track STR1 after writing to track STR0. The first prediction overshoot is the minimum prediction overshoot, and the prediction upper limit threshold is the maximum prediction upper limit threshold. The cumulative prediction overshoot is below the prediction upper limit threshold, therefore, the determination unit 67 can determine that the write operation to track STR1 can continue.

[0275] On the other hand, Figure 16 In the example, the second prediction exceeds the amount equivalent to a seek distance of 2 tracks or more, and the head HD shaking becomes the maximum. Figure 14 For example, during the first write operation, write processing is performed until the nth object sector RSCn of track STR1 is reached, then a seek operation is performed, and during the second write operation, an attempt is made to restart write processing from the (n+1)th object sector RSC(n+1) of track STR1. The second prediction overshoot is the maximum prediction overshoot, and the prediction upper limit threshold is the minimum prediction upper limit threshold. The cumulative prediction overshoot exceeds the prediction upper limit threshold, therefore, the determination unit 67 can determine that write processing to track STR1 needs to be aborted (or terminated).

[0276] Next, the survey results on the frequency of PTS occurrences will be explained. Figure 17 This is a bar chart showing the number (occurrence rate) of PTS (Packet Switching) when disk device 1 uses mode 1 of the second write operation and mode 2 of the second write operation.

[0277] like Figure 17 As shown, compared to the first method using the second write operation, the second method of the second write operation reduces the frequency of aborting (or ending) the write processing of the second track STR1 because it does not cause the cumulative prediction to exceed the limit. The second method of the second write operation helps improve the write performance of disk device 1 by reducing the PTS startup frequency.

[0278] Furthermore, although a bar chart for the third mode of the second write operation is not shown, the third mode of the second write operation can also reduce the PTS startup frequency, which can help improve the write performance of disk device 1.

[0279] Next, a flowchart will be used to illustrate the first action. Figure 18 This is a flowchart illustrating the write processing method for the nth target sector RSCn of the second track STR1 in the write processing method according to this embodiment. It is a diagram of the disk device 1 using the first write operation during the first write.

[0280] like Figure 18 , Figure 1 and Figure 12 As shown, after the first write operation begins, firstly, in step ST1a, the write processing unit 62 performs write processing on the nth target sector RSCn of the second track STR1. Next, in step ST2a, the correction limit prediction unit 66 determines whether the positioning error PE exceeds the reference radius position PO.

[0281] If the positioning error PE exceeds the reference radius position PO (step ST2a: Yes), proceed to step ST3a, where the write processing unit 62 stops the write processing of track STR1. Next, in step ST4a, the write processing unit 62 begins the write retry processing of track STR1. Thus, the first write operation ends.

[0282] On the other hand, if the positioning error PE is below the reference radius position PO (step ST2a: no), the process moves to step ST5a, and the write processing unit 62 continues to write the second track STR1, ending the first write operation.

[0283] Next, a flowchart will be used to illustrate the second method of the second write action, which sets the upper limit of the prediction threshold to a constant. Figure 19 This is a flowchart illustrating the write processing method for the nth target sector RSCn of the second track STR1 in the write processing method according to this embodiment. It is a diagram of the second mode in which the disk device 1 uses the second write operation during the first write. Figure 20 Is following Figure 19 The following is a flowchart illustrating the write processing method.

[0284] like Figure 19 , Figure 1 , Figure 12 and Figure 15As shown, after the second write operation begins with the prediction upper limit threshold set to a constant in the second mode, firstly, in step ST1b, the write processing unit 62 performs write processing on the nth target sector RSCn of the second track STR1. Next, in step ST2b, the correction limit prediction unit 66 determines whether the positioning error PE exceeds the reference radius position PO.

[0285] If the positioning error PE exceeds the reference radius position PO (step ST2b: Yes), the process moves to step ST3b, where the determination unit 67 determines whether the number of damaged target sectors CSCs on track STR0 exceeds the upper limit (e.g., 12). If the number of damaged target sectors CSCs on track STR0 exceeds the upper limit (step ST3b: Yes), the process moves to step ST4b, where the write processing unit 62 ends the write processing on track STR1, and in step ST5b, the disk device 1 starts PTS. Thus, the second mode of the second write operation ends.

[0286] On the other hand, if the positioning error PE is less than or equal to the reference radius position PO (step ST2b: no), the process moves to step ST6b, and the write processing unit 62 continues to write to the second track STR1, ending the second write operation in the second mode.

[0287] like Figure 20 , Figure 1 , Figure 12 and Figure 15 As shown, if the number of damaged sector CSCs in track STR0 of track 1 is less than the upper limit (step ST3b: No), proceed to step ST7b, where the determination unit 67 determines whether the cumulative measured excess exceeds the predicted upper limit threshold. If the cumulative measured excess exceeds the predicted upper limit threshold (step ST7b: Yes), proceed to... Figure 19 Step ST4b.

[0288] On the other hand, if the cumulative measured excess is below the upper limit of the prediction threshold (step ST7b: No), proceed to step ST8b, where the disk device 1 determines whether the first distance that moves the read head RHD is greater than or equal to the distance of moving two tracks. If the first distance is greater than or equal to the distance of moving two tracks (step ST8b: Yes), proceed to step ST9b, where the adjustment unit 65 calculates a second predicted excess that is greater than the first predicted excess (adjusting the first predicted excess to the second predicted excess), and the correction limit prediction unit 66 adds the second predicted excess to the cumulative measured excess to calculate (recalculate) the second cumulative predicted excess, and proceed to step ST11b.

[0289] If the first distance is less than the distance of moving two tracks (step ST8b: No), proceed to step ST10b, the correction limit prediction unit 66 maintains the calculated first cumulative prediction over-limit, and proceeds to step ST11b. Next, in step ST11b, the determination unit 67 determines whether the first cumulative prediction over-limit (or the second cumulative prediction over-limit) exceeds the prediction upper limit threshold.

[0290] If the first cumulative forecast overshoot (or the second cumulative forecast overshoot) is below the upper forecast threshold (step ST11b: No), move to Figure 19 Step ST6b. On the other hand, if the first cumulative forecast overshoot (or the second cumulative forecast overshoot) exceeds the forecast upper limit threshold (step ST11b: yes), move to Figure 19 Step ST4b.

[0291] Next, a flowchart will be used to illustrate the third way of the second write action, which sets the upper limit of the prediction threshold to a constant. Figure 21 This is a flowchart illustrating the write processing method for the nth target sector RSCn of the second track STR1 in the write processing method according to this embodiment. It is a diagram of the disk device 1 employing a third mode of the second write operation during the first write period and the second write period. Figure 22 Is following Figure 21 The following is a flowchart illustrating the write processing method. Figure 23 Is following Figure 22 The following is a flowchart illustrating the write processing method.

[0292] like Figure 21 , Figure 1 , Figure 12 and Figure 16 As shown, after the third mode of the second write operation, in which the prediction upper limit threshold is set to a constant, begins, firstly, in step ST1c, the write processing unit 62 performs write processing on the nth target sector RSCn of the second track STR1. Next, in step ST2c, the correction limit prediction unit 66 determines whether the positioning error PE exceeds the reference radius position PO.

[0293] If the positioning error PE exceeds the reference radius position PO (step ST2c: Yes), the process moves to step ST3c, where the determination unit 67 determines whether the number of damaged target sectors CSCs on track STR0 exceeds the upper limit (e.g., 12). If the number of damaged target sectors CSCs on track STR0 exceeds the upper limit (step ST3c: Yes), the process moves to step ST4c, where the write processing unit 62 ends the write processing on track STR1, and in step ST5c, the disk device 1 starts PTS. Thus, the third mode of the second write operation ends.

[0294] On the other hand, if the positioning error PE is less than or equal to the reference radius position PO (step ST2c: no), the process moves to step ST6c, and the write processing unit 62 continues to write to the second track STR1, ending the second write operation in the third mode.

[0295] like Figure 22 , Figure 1 , Figure 12 and Figure 16 As shown, if the number of damaged sector CSCs in track STR0 of track 1 is less than the upper limit (step ST3c: No), proceed to step ST7c, where the determination unit 67 determines whether the cumulative measured excess exceeds the predicted upper limit threshold. If the cumulative measured excess exceeds the predicted upper limit threshold (step ST7c: Yes), proceed to... Figure 21 Step ST4c.

[0296] On the other hand, if the cumulative measured excess is below the prediction upper limit threshold (step ST7c: No), the process moves to step ST8c, where the disk device 1 determines whether the first distance that moves the read head RHD is greater than or equal to the distance of moving two tracks. If the first distance is less than the distance of moving two tracks (step ST8c: No), the process moves to step ST10c, where the correction limit prediction unit 66 maintains the calculated first cumulative prediction excess and moves to step ST11c. Next, in step ST11c, the determination unit 67 determines whether the first cumulative prediction excess (or the second cumulative prediction excess) exceeds the prediction upper limit threshold.

[0297] If the first cumulative forecast overshoot (or the second cumulative forecast overshoot) is below the upper forecast threshold (step ST11c: No), move to Figure 21 Step ST6c. On the other hand, if the first cumulative forecast overshoot (or the second cumulative forecast overshoot) exceeds the forecast upper limit threshold (step ST11c: Yes), move to Figure 21 Step ST4c.

[0298] like Figure 23 , Figure 1 , Figure 12 and Figure 16 As shown, if the first distance is greater than the distance of moving two magnetic tracks (step ST8c: Yes), proceed to step ST9c, the adjustment unit 65 calculates a second predicted excess that is greater than the first predicted excess (adjusting the first predicted excess to the second predicted excess), the correction limit prediction unit 66 adds the second predicted excess to the cumulative measured excess to calculate (recalculate) the second cumulative predicted excess, and proceed to step ST12c.

[0299] In step ST12c, the determination unit 67 determines whether the second cumulative prediction overshoot exceeds the prediction upper limit threshold. If the second cumulative prediction overshoot is below the prediction upper limit threshold (step ST12c: No), the process moves to... Figure 21 Step ST6c. On the other hand, if the second cumulative prediction exceeds the prediction upper limit threshold (step ST12c: yes), proceed to step ST13c, and the write processing unit 62 stops the write processing of the second track STR1.

[0300] Next, in step ST14c, the determination unit 67 performs a waiting-for-rotation action during one revolution of disk DK. Then, proceeding to step ST15c, the adjustment unit 65 adjusts the second predicted excess to the minimum predicted excess, and the correction limit prediction unit 66 calculates (recalculates) the minimum cumulative predicted excess by adding the minimum predicted excess to the cumulative measured excess. Figure 22 Step ST11c.

[0301] According to the disk device 1 of the first embodiment configured as described above, the disk device 1 includes a disk DK, a header HD, a read processing unit 63, a write processing unit 62, an error correction unit 64, an adjustment unit 65, a correction limit prediction unit 66, and a judgment unit 67.

[0302] During the first write operation, the read processing unit 63 performs a first seek operation to move the read head RHD a first distance, bringing the write head WHD towards the second track STR1. The adjustment unit 65 derives a first prediction overshoot and a prediction upper limit threshold. The correction limit prediction unit 66 calculates a first cumulative prediction overshoot. The determination unit 67 can, if it determines that the first cumulative prediction overshoot is below the prediction upper limit threshold, cause the write processing unit 62 to continue writing to the second track STR1. The determination unit 67 can, if it determines that the first cumulative prediction overshoot exceeds the prediction upper limit threshold, cause the write processing unit 62 to stop writing to the second track STR1.

[0303] The adjustment unit 65 can adjust the prediction overshoot. Since the cumulative prediction overshoot does not become excessive, the frequency of aborting (or ending) write processing on track STR1 can be reduced. Furthermore, the PTS startup frequency can be reduced. Moreover, it can help improve the write performance of disk device 1.

[0304] As can be seen from the above, a disk device 1 is available that can predict whether the error correction of the track STR of disk DK has reached its limit in relation to the seek operation.

[0305] The embodiments of the present invention have been described above, but these embodiments are merely illustrative examples and are not intended to limit the scope of the invention. The new embodiments described above can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above embodiments and their variations are included within the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A disk drive, comprising: The disk has a first data track and a second data track adjacent to each other in the recording layer. Each of the first data track and the second data track includes a plurality of object sectors as objects to which data is written. From the view of the second data track, the first data track is located in a first direction parallel to the radial direction of the disk. The head has a write head for writing data to the recording layer and a read head for reading data from the recording layer; The read processing unit is capable of performing seek processing to enable the read head to seek data. The write processing unit is capable of performing write processing on the data written to the recording layer; The error correction unit performs error correction on the data of one or more damaged object sectors among the plurality of object sectors of the first data track that are determined to be corrupted. Adjustment Department; Correction limit prediction unit; and Judgment Department The first write period is the period between when the write processing unit performs the write processing on the plurality of object sectors of the first data track and when it performs the write processing on the plurality of object sectors of the second data track. The read processing unit performs a first seek process to cause the read head to seek a track, moving the read head a first distance so that the write head faces the second data track. The adjustment part, A first predicted overshoot is derived, which is the predicted overshoot by which the position of the write head exceeds a reference radius position in the first direction during the first write, and varies based on the distance required for the read head to seek. A prediction upper limit threshold is derived, which is a constant representing the limit of the feasible range of error correction for the first data track. The correction limit prediction unit, whenever writing data to each of the target sectors of the second data track, measures the measured excess amount by which the position of the write head exceeds the reference radius position in the first direction, updates the cumulative measured excess amount as the accumulated measured excess amount, and calculates the first cumulative predicted excess amount by adding the first predicted excess amount to the cumulative measured excess amount. The judgment unit If it is determined that the first cumulative prediction exceeds the upper limit threshold of the prediction, the write processing unit continues to perform the write processing on the second data track. If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the second data track.

2. The disk drive according to claim 1, The plurality of object sectors of the second data track includes the nth object sector and the (n+1)th object sector following the nth object sector in the direction of travel of the head relative to the recording layer. During the first writing, The write processing unit performs the write processing up to the nth object sector of the second data track. The correction limit prediction unit measures the measured excess and updates the cumulative measured excess. Furthermore, it adds the first predicted excess to the cumulative measured excess to calculate the first cumulative predicted excess, which is anticipated as the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the first write operation. The judgment unit If it is determined that the first cumulative prediction exceeds the upper limit threshold, the write processing unit continues to perform the write processing on the (n+1)th object sector of the second data track. If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the (n+1)th object sector of the second data track.

3. The disk drive according to claim 1, When the first distance is less than or equal to the distance that moves the read head by one data track in the radial direction, the adjustment unit adjusts the first prediction overshoot to a minimum, i.e., a minimum prediction overshoot. If the first distance is greater than or equal to the distance by which the read head moves two data tracks in the radial direction, the adjustment unit adjusts the first prediction overshoot to an amount greater than the minimum prediction overshoot.

4. The disk drive according to claim 3, During the first writing, When the first distance by which the read head is moved by the read processing unit is greater than or equal to the distance of moving two data tracks, and the first prediction overshoot adjusted by the adjustment unit is greater than the minimum amount, and the determination unit determines that the first cumulative prediction overshoot exceeds the prediction upper limit threshold. The correction limit prediction unit then adds the minimum predicted excess to the cumulative measured excess to calculate the minimum cumulative predicted excess. The judgment unit If it is determined that the minimum cumulative prediction exceeds the upper prediction threshold, the drive of the write processing unit is controlled to stop the write processing on the second data track, maintain the position of the write head in the radial direction, and switch to a write retry operation that waits for the disk to rotate before restarting the write processing. If it is determined that the minimum cumulative prediction exceeds the prediction upper limit threshold, the write processing unit terminates the write processing of the second data track and transfers the remaining data that could not be written to the second data track to a recording area outside the first and second data tracks.

5. The disk drive according to claim 1, The plurality of object sectors of the second data track includes the nth object sector and the (n+1)th object sector following the nth object sector in the direction of travel of the head relative to the recording layer. If the write process is performed during the first write operation up to the nth object sector of the second data track, and the read head seeks after the first write operation, and then the write process restarts during the second write operation from the (n+1)th object sector of the second data track, During the first writing, The write processing unit performs the write processing up to the nth object sector of the second data track. The correction limit prediction unit measures the measured excess and updates the cumulative measured excess. Furthermore, it adds the first predicted excess to the cumulative measured excess to calculate the first cumulative predicted excess, which is anticipated as the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the first write operation. During the second writing, The read processing unit performs a second seek process to cause the read head to seek a track, moving the read head a second distance so that the write head is once again facing the second data track. The adjustment unit re-derives a second predicted overshoot, which corresponds to the second distance and is the predicted overshoot that the position of the write head exceeds the reference radius position in the first direction during the second write operation. The correction limit prediction unit recalculates the second cumulative predicted excess by adding the second predicted excess to the cumulative measured excess. The second predicted excess is anticipated to be the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the second write operation. The judgment unit If it is determined that the second cumulative prediction exceeds the upper limit threshold, the write processing unit restarts the write processing of the (n+1)th object sector of the second data track. If it is determined that the second cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the (n+1)th object sector of the second data track.

6. The disk drive according to claim 5, The period during which the read processing unit performs the second seek process includes an acceleration period as the initial period and a deceleration period as the final period. The read processing unit, During the acceleration, the read head gradually increases its speed while seeking in the first seek direction. During the deceleration, the read head gradually reduces its speed while seeking in the first seek direction.

7. The disk drive according to claim 1, The write processing unit is a watt-type recorder that writes data of the second data track onto the data of the first data track in an overlapping write direction opposite to the first direction.

8. A disk drive, comprising: The disk has a first data track and a second data track adjacent to each other in the recording layer. Each of the first data track and the second data track includes a plurality of object sectors as objects to which data is written. From the view of the second data track, the first data track is located in a first direction parallel to the radial direction of the disk. The head has a write head for writing data to the recording layer and a read head for reading data from the recording layer; The read processing unit is capable of performing seek processing to enable the read head to seek data. The write processing unit is capable of performing write processing on the data written to the recording layer; The error correction unit performs error correction on the data of one or more damaged object sectors among the plurality of object sectors of the first data track that are determined to be corrupted. Adjustment Department; Correction limit prediction unit; and Judgment Department The first write period is the period between when the write processing unit performs the write processing on the plurality of object sectors of the first data track and when it performs the write processing on the plurality of object sectors of the second data track. The read processing unit performs a first seek process to cause the read head to seek a track, moving the read head a first distance so that the write head faces the second data track. The adjustment part, A first predicted overshoot is derived, which is a predicted overshoot that the position of the write head exceeds a reference radius position in the first direction during the first write, varying according to the distance the read head seeks. A prediction upper limit threshold is derived. This prediction upper limit threshold is a variable representing the limit of the feasible range of error correction for the first data track. The greater the number of prediction overshoots, including the first prediction overshoot, the smaller the prediction upper limit threshold will be. The correction limit prediction unit, whenever writing data to each of the target sectors of the second data track, measures the measured excess amount by which the position of the write head exceeds the reference radius position in the first direction, updates the accumulated measured excess amount, and calculates a first cumulative predicted excess amount by adding the first predicted excess amount to the accumulated measured excess amount. The judgment unit If it is determined that the first cumulative prediction exceeds the upper limit threshold of the prediction, the write processing unit continues to perform the write processing on the second data track. If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the second data track.

9. The disk drive according to claim 8, The plurality of object sectors of the second data track includes the nth object sector and the (n+1)th object sector following the nth object sector in the direction of travel of the head relative to the recording layer. During the first writing, The write processing unit performs the write processing up to the nth object sector of the second data track. The correction limit prediction unit measures the measured excess and updates the cumulative measured excess. Furthermore, it adds the first predicted excess to the cumulative measured excess to calculate the first cumulative predicted excess, which is anticipated as the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the first write operation. The judgment unit If it is determined that the first cumulative prediction exceeds the upper limit threshold, the write processing unit continues to perform the write processing on the (n+1)th object sector of the second data track. If it is determined that the first cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the (n+1)th object sector of the second data track.

10. The disk drive according to claim 8, When the first distance is less than or equal to the distance by which the read head moves one data track in the radial direction, the adjustment unit adjusts the first prediction overshoot to a minimum, i.e., the minimum prediction overshoot, and adjusts the prediction upper limit threshold to a maximum, i.e., the maximum prediction upper limit threshold. When the first distance is greater than or equal to the distance by which the read head moves two data tracks in the radial direction, the adjustment unit adjusts the first prediction overshoot to an amount greater than the minimum prediction overshoot, and adjusts the prediction upper limit threshold to a value smaller than the maximum prediction upper limit threshold.

11. The disk drive according to claim 10, During the first writing, When the first distance by which the read head is moved by the read processing unit is greater than or equal to the distance of moving two data tracks, and the first prediction overshoot adjusted by the adjustment unit is greater than the minimum amount, and the prediction upper limit threshold adjusted by the adjustment unit is less than the maximum prediction upper limit threshold, and the determination unit determines that the first cumulative prediction overshoot exceeds the prediction upper limit threshold. The correction limit prediction unit then adds the minimum predicted excess to the cumulative measured excess to calculate the minimum cumulative predicted excess. The judgment unit If it is determined that the minimum cumulative prediction exceeds the upper prediction threshold, the drive of the write processing unit is controlled to stop the write processing on the second data track, maintain the position of the write head in the radial direction, and switch to a write retry operation that waits for the disk to rotate before restarting the write processing. If it is determined that the minimum cumulative prediction exceeds the prediction upper limit threshold, the write processing unit terminates the write processing of the second data track and transfers the remaining data that could not be written to the second data track to a recording area outside the first and second data tracks.

12. The disk drive according to claim 8, The plurality of object sectors of the second data track includes the nth object sector and the (n+1)th object sector following the nth object sector in the direction of travel of the head relative to the recording layer. If the write process is performed during the first write operation up to the nth object sector of the second data track, and the read head seeks after the first write operation, and then the write process restarts during the second write operation from the (n+1)th object sector of the second data track, During the first writing, The write processing unit performs the write processing up to the nth object sector of the second data track. The correction limit prediction unit measures the measured excess and updates the cumulative measured excess. Furthermore, it adds the first predicted excess to the cumulative measured excess to calculate the first cumulative predicted excess, which is anticipated as the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the first write operation. During the second writing, The read processing unit performs a second seek process to cause the read head to seek a track, moving the read head a second distance so that the write head is once again facing the second data track. The adjustment part, The second predicted overshoot is re-derived, corresponding to the second distance, and is the predicted overshoot that the position of the write head exceeds the reference radius position in the first direction during the second write operation. The upper limit threshold for prediction is adjusted to a value corresponding to the second prediction over-limit. The correction limit prediction unit recalculates the second cumulative predicted excess by adding the second predicted excess to the cumulative measured excess. The second predicted excess is anticipated to be the amount by which the write head position exceeds the reference radius position in the first direction, assuming data is written to the (n+1)th object sector during the second write operation. The judgment unit If it is determined that the second cumulative prediction exceeds the upper limit threshold, the write processing unit restarts the write processing of the (n+1)th object sector of the second data track. If it is determined that the second cumulative prediction exceeds the prediction upper limit threshold, the write processing unit stops the write processing of the (n+1)th object sector of the second data track.

13. The disk drive according to claim 12, The period during which the read processing unit performs the second seek process includes an acceleration period as the initial period and a deceleration period as the final period. The read processing unit, During the acceleration, the read head gradually increases its speed while seeking in the first seek direction. During the deceleration, the read head gradually reduces its speed while seeking in the first seek direction.

14. The disk drive according to claim 8, The write processing unit is capable of selecting a watt-type recorder that writes data of the second data track overlapping the data of the first data track in an overlapping write direction opposite to the first direction.

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