Magnetic disk drive

Abstract

The present invention provides a magnetic disk device that can improve the recording density of data on the disk and suppress the degradation of write performance. [Solution] During the first write period, if the determination unit 67 determines that the error correction of the first user data on the first data track has not exceeded the limit, it instructs the write processing unit 62 to continue the write process and the management unit 65 to perform the second management. If the determination unit 67 determines that the above error correction has exceeded the limit, it instructs the write processing unit 62 to continue the write process and the management unit 65 to perform the third management. During or after the first write period, the determination unit 67 instructs the management unit 65 to perform the process of saving the data belonging to the third group to a non-volatile recording medium.

Description

Technical Field

[0001] Embodiments of the present invention relate to a magnetic disk drive.

Background Art

[0002] As magnetic disk drives, there are known a magnetic disk drive of a Conventional Magnetic Recording (CMR) format (or, conventional recording format) that writes a plurality of tracks at intervals in the radial direction of the disk, a magnetic disk drive of a Shingled Magnetic Recording (SMR) format that overwrites a plurality of tracks in the radial direction of the disk, and a magnetic disk drive of a hybrid recording format that selects and executes the conventional recording format and the shingled recording format.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present embodiment provides a magnetic disk drive that can improve the recording density of data on a disk and suppress a decrease in write performance.

Means for Solving the Problems

[0005] A magnetic disk device according to one embodiment is described as follows: A disk having a first data track and a second data track adjacent to each other on a recording layer, wherein the first data track and the second data track each include a plurality of target sectors on which data is to be written, and the first data track is located in a first direction parallel to the radial direction of the disk with respect to the second data track, A head having a write head for writing data to the recording layer and a read head for reading data from the recording layer, A read processing unit capable of performing a seek operation to seek the read head, A write processing unit capable of performing a write operation to write data to the recording layer, An error correction unit that performs error correction on the data of one or more corrupted target sectors of the first data track that are determined to have corrupted data, A buffer memory capable of holding multiple data, including first user data and second user data, A management unit capable of selectively executing: a first management that prohibits overwriting the first user data in the buffer memory; a second management that permits overwriting all of the first user data in the buffer memory; and a third management that permits overwriting data belonging to the first group and the second group of the first user data in the buffer memory, while prohibiting overwriting data belonging to the third group of the first user data in the buffer memory. Correction limit determination unit, It comprises a determination unit, During the first write period, which is the period after the write processing unit has performed the write processing to write the first data including the first user data to the plurality of target sectors of the first data track and during the period in which the write processing unit performs the write processing to write the second data including the second user data to the plurality of target sectors of the second data track, The read processing unit performs a seek process to move the read head, and positions the write head opposite the second data track. The correction limit determination unit acquires information that the position of the light head extends beyond the reference radius position in the first direction each time data is written to the target sector of the second data track. The management unit shall perform the first management, The unit that makes the determination said, Based on the information acquired by the correction limit determination unit, if it determines that the error correction of the first user data on the first data track by the error correction unit has not exceeded the limit, the write processing unit is instructed to continue the write process on the second data track, and the management unit is instructed to perform the second management instead of the first management. Based on the aforementioned information, if the error correction unit determines that the error correction of the first user data on the first data track has exceeded its limit, the write processing unit is instructed to continue the write process on the second data track, and the management unit is instructed to perform the third management instead of the first management. During the first light period, or after the first light period, The determination unit causes the management unit to perform a process to save the data belonging to the third group to a non-volatile recording medium. The data belonging to the first group is the original data of one or more target sectors of the first data track that are determined not to be corrupted. The data belonging to the second group is the original data of one or more first corrupted target sectors of the first data track that are determined to be corrupted, and is the original data of data within the range in which the error correction unit can perform the error correction. The data belonging to the third group is the original data of one or more second corrupted target sectors of the first data track that are determined to be corrupted, and is the original data of data that falls outside the range in which the error correction unit can perform the error correction. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a block diagram showing the configuration of a magnetic disk device according to one embodiment. [Figure 2] Figure 2 is a perspective view showing a part of the magnetic disk drive described above, and shows multiple disks and multiple heads. [Figure 3] Figure 3 is a schematic diagram showing an example of the arrangement of multiple servo areas and multiple data areas on a single disk according to the above embodiment. [Figure 4] Figure 4 is a schematic diagram showing the three tracks in the user data area where the disk recording process shown in Figure 3 takes place, as well as the write head. [Figure 5] Figure 5 is a schematic diagram showing the three tracks of the media cache where the normal recording process of the disk shown in Figure 3 takes place, as well as the write head. [Figure 6] Figure 6 is a schematic diagram illustrating an example of data writing to a disk. [Figure 7] Figure 7 is a schematic diagram showing two bands and one guard band from the user data area shown in Figure 6. [Figure 8] Figure 8 is a schematic diagram showing three sectors of one track in the band shown in Figure 6. [Figure 9] Figure 9 is a schematic diagram showing the two bands and one guard band shown in Figure 7, and is a diagram for illustrating multiple target sectors and multiple unused sectors. [Figure 10]Figure 10 is a schematic diagram showing an example of the first and second tracks, assuming that the magnetic disk device does not have the function to perform track-level error correction on the track data; it is a diagram for explaining the write process to the first and second tracks; it is a diagram for explaining the state in which the write process to the second track is continued until the sector-level error correction to the first track reaches its limit; and it is a diagram that shows the change in BER for the first track and the change in BER with respect to positioning error, respectively, in graph form. [Figure 11] Figure 11 is a schematic diagram showing an example of the first and second tracks, assuming that the magnetic disk device does not have the function to perform track-level error correction on the track data. It is a diagram to explain the write process for the first and second tracks. It is a diagram to explain the state in which the write process for the second track is terminated when the judgment value is set to a write-off track slice smaller than the track margin (stricter) and it is detected that the positioning error exceeds the reference radius position. It is a diagram that shows the change in BER for the first track and the change in BER for the positioning error in graph form. [Figure 12] Figure 12 is a schematic diagram showing an example of the first and second tracks of the magnetic disk device described above, which has a function to perform track-level error correction on the data of the tracks. It is a diagram for explaining the write process for the first and second tracks. It is a diagram for explaining a state in which the write-off track slice is set to be larger (looser) than the track margin, and the write process for the second track continues even if the track-level error correction for the first track exceeds the limit. The diagram shows the change in BER for the first track and the change in BER for positioning error, respectively, in graph form. [Figure 13]FIG. 13 is a diagram showing in a table the presence or absence of track ECC in the first and second methods of the first light operation and the second light operation, the function name for controlling the DOL, the content of the process when the positioning error exceeds the reference radius position, the setting regarding overwriting of data in the buffer memory, and the setting regarding saving of data in the buffer memory. [Figure 14] FIG. 14 is a diagram showing the change in the positioning error and the change in the cumulative number of damaged target sectors when performing a write process on the second track in the first method of the second light operation, and is a diagram showing the case where the cumulative number exceeds the PTS activation threshold during the write process to the n-th target sector of the second track. [Figure 15] FIG. 15 is a diagram showing the change in the positioning error and the change in the cumulative number of damaged target sectors when performing a write process on the second track in the second method of the second light operation, and is a diagram showing the case where the cumulative number exceeds the upper limit number during the write process to the n-th target sector of the second track. [Figure 16] FIG. 16 is a diagram showing the change in the positioning error and the change in the cumulative measured excess amount when performing a write process on the second track in the second method of the second light operation, and is a diagram showing the case where the cumulative measured excess amount exceeds the upper limit threshold during the write process to the n-th target sector of the second track. [Figure 17] FIG. 17 is a flowchart showing the write process method for the n-th target sector of the second track among the write process methods according to the above embodiment, and is a diagram when the magnetic disk device adopts the second method of the second light operation during the first write period. [Figure 18] FIG. 18 is a flowchart showing the above write process method, following FIG. 17. [Figure 19] FIG. 19 is a modified example of the flowchart showing the above write process method, following FIG. 17.

Embodiments for Carrying Out the Invention

[0007] Hereinafter, a magnetic disk device 1 according to one embodiment will be described in detail with reference to the drawings. First, the configuration of the magnetic disk device 1 will be described. Figure 1 is a block diagram showing the configuration of the magnetic disk device 1 according to this embodiment. In this embodiment, the magnetic disk device 1 is a hybrid recording type magnetic disk device that can select and perform both normal recording and tile recording. However, the technology described later may be applied to a tile recording type magnetic disk device or a normal recording type magnetic disk device.

[0008] As shown in Figure 1, the magnetic disk drive 1 comprises a plurality of disks (magnetic disks) DK as recording media, for example, 1 to 10 disks, 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 head amplifier IC or preamplifier) ​​130, a volatile memory 70, a buffer memory (buffer) 80, a non-volatile memory 90, and a system controller 110 which is a single-chip integrated circuit. The magnetic disk drive 1 is also connected to a host system (hereinafter simply referred to as host) 100.

[0009] Each disk 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. In this embodiment, the magnetic disk device 1 is equipped with 1 to 11 disks DK, but the number of disks DK is not limited to these.

[0010] The head stack assembly 22 can move the head HD mounted on the arm 30 to a target position on the disk DK, i.e., seek, by driving the voice coil motor (hereinafter referred to as VCM) 24. The VCM 24 functions as an actuator. Disk DK has two areas allocated to its writable data: a user data area U, which is accessible to users, and a system area S, which is used to write information necessary for system management.

[0011] The head HD records and plays back information to and from the disk DK. The head HD consists of a slider as its main body, 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 track of the recording layer of the disk DK.

[0012] Sometimes the "center of the head HD" is referred to as "head HD," the "center of the light head WHD" as "light head WHD," and the "center of the read head RHD" as "read head RHD." Sometimes the "center of the light head WHD" is simply referred to as "head HD," and sometimes the "center of the read head RHD" is simply referred to as "head HD."

[0013] The driver IC 120 controls the driving of the SPM20 and VCM24 according to the control of the system controller 110 (specifically, the MPU 60, which will be described later). The SPM20 supports and rotates multiple disk DKs.

[0014] The head amplifier IC 130 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, which will be described later). The write driver outputs a write current to the head HD corresponding to the signal output from the R / W channel 140.

[0015] The volatile memory 70 is a semiconductor memory in which the data stored is lost when the power supply is cut off. The volatile memory 70 stores data necessary for processing in each part of the magnetic disk device 1. The volatile memory 70 is a random access memory (RAM). For example, the volatile memory 70 is a DRAM (Dynamic Random Access Memory). However, the volatile memory 70 may also be an SDRAM (Synchronous Dynamic Random Access Memory).

[0016] The buffer memory 80 is a semiconductor memory that temporarily records data transmitted and received between the magnetic disk device 1 and the host 100. The buffer memory 80 may be integrated with the volatile memory 70. The buffer memory 80 is a volatile RAM. Examples of buffer memory 80 include DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), and MRAM (Magnetoresistive Random Access Memory). The buffer memory 80 includes areas used as read cache and write cache, and temporarily stores commands and other information received from the host 100.

[0017] Non-volatile memory 90 is a semiconductor memory that retains stored data even when the power supply is cut off. Non-volatile memory 90 is, for example, a NAND-type flash read-only memory (FROM). However, non-volatile memory 90 may also be a NOR-type FROM.

[0018] The system controller (controller) 110 is implemented, for example, using a large-scale integrated circuit (LSI) called a System-on-a-Chip (SoC), in which multiple elements are integrated 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, a volatile memory 70, a buffer memory 80, a non-volatile memory 90, and a host 100.

[0019] The R / W channel 140 performs signal processing for read data transferred from disk DK to host 100 and write data transferred from host 100, in response to instructions from the MPU 60, which will be described later. The R / W channel 140 has a circuit or function for modulating the write data. The R / W channel 140 also has a circuit or function for measuring the signal quality of the read data. The R / W channel 140 is electrically connected to, for example, the head amplifier IC 130, HDC 150, MPU 60, etc.

[0020] The HDC150 controls data transfer between the host 100 and the R / W channel 140 in response to instructions from the MPU60. The HDC150 is electrically connected to, for example, the R / W channel 140, the MPU60, the volatile memory 70, the buffer memory 80, the non-volatile memory 90, etc.

[0021] The HDC150 has a gate generation unit. The gate generation unit generates various gates, such as write gates, read gates, and servo gates, in response to commands from the host 100, instructions from the MPU 60, etc., and outputs them to the R / W channel 140, for example, the gate detection unit. Hereinafter, "raising a predetermined gate" may be referred to as "asserting a predetermined gate." Similarly, "lowering a predetermined gate" may be referred to as "negating a predetermined gate." "Asserting a predetermined gate" and "negating a predetermined gate" may also include the meaning of "generating a predetermined gate." The gate generation unit may be included in the R / W channel 140 or the MPU 60.

[0022] The R / W channel 140 has a gate detection unit. The gate detection unit detects whether various gates, such as a light gate, read gate, or servo gate, are in an asserted or negated state. For example, the gate detection unit executes the write process when it detects that the write gate is asserted, and pauses (stops) the write process when it detects that the write gate is negated. In addition, the gate detection unit executes read processing when it detects that a read gate is asserted, and stops read processing when it detects that a read gate is negated. The gate detection unit executes servo read processing when it detects that a servo gate is asserted, and stops servo read processing when it detects that a servo gate is negated. The gate detection unit may be located within the HDC150 or MPU60.

[0023] The MPU60 is a control unit that controls various parts of the magnetic disk drive 1 and is the main controller. The MPU60 controls the VCM24 via the driver IC120 and performs servo control to position the head HD. The MPU60 controls the write operation of data to the disk DK and selects the storage location for the write data transferred from the host 100. The MPU60 also controls the read operation of data from the disk DK and controls the processing of the read data transferred from the disk DK to the host 100. The MPU60 is connected to various parts of the magnetic disk drive 1. For example, the MPU60 is electrically connected to the driver IC120, R / W channel 140, HDC150, etc.

[0024] The MPU 60 includes a read / write processing unit 61, an error correction unit 64, a management unit 65, a correction limit determination unit 66, a judgment unit 67, and the like. The MPU 60 executes the processing of each of these units, such as the read / write processing unit 61, the error correction unit 64, the management unit 65, the correction limit determination unit 66, and the judgment unit 67, on the firmware. The MPU 60 may also include each of these units as a circuit.

[0025] 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 data writing process, and the read processing unit 63 controls the data reading process, causing the read head RHD to read data from the disk DK. The read processing unit 63 is capable of performing a seek process to cause the read head RHD to seek. The write processing unit 62 is capable of performing a write process to write data to the recording layer of the disk DK. The read / write processing unit 61 controls the VCM24 via the driver IC 120 to position the head HD at a target position (a predetermined radius position) on the disk DK and execute a read or write operation.

[0026] Figure 2 is a perspective view showing a part of the magnetic disk drive 1, and shows multiple disks DK and multiple heads HD. As shown in Figure 2, the direction in which the disk DK rotates in the circumferential direction is called the rotation direction d3. In the example shown in Figure 2, the rotation direction d3 is shown as counterclockwise, but it may also be in the opposite direction (clockwise). Furthermore, the direction of travel d2 of the head HD relative to the disk DK is opposite to the rotation direction d3. The direction of travel d2 is the direction in which the head HD sequentially writes and reads data relative to the disk DK in the circumferential direction, that is, the direction in which the head HD moves relative to the disk DK in the circumferential direction.

[0027] The magnetic disk drive 1 comprises i disks, numbered DK1 to DKi, and j heads, numbered HD1 to HDj. In this embodiment, the number of heads HD is twice the number of disks DK (j = 2 × i). Disks DK1 through DKi are mounted coaxially and stacked with a gap between them. Disks DK1 through DKi have the same diameter. Here, terms such as “same,” “identical,” “matching,” and “equivalent” include not only the meaning of being exactly the same, but also the meaning of being different to the extent that they can be considered substantially the same. Note that the diameters of disks DK1 through DKi may differ from each other.

[0028] 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 may also be referred to as the front or recording surface. Each second recording layer Lb may also be referred to as the back or recording surface. However, each first recording layer La is sometimes referred to as the back surface. In this case, each second recording layer Lb is sometimes referred to as the front surface.

[0029] Each recording layer L has a user data area U and a system area S. The first recording layer La1 has a user data area Ua1 and a system area Sa1. The second recording layer Lb1 has a user data area Ub1 and a system area Sb1. The first recording layer La2 has a user data area Ua2 and a system area Sa2. The second recording layer Lb2 has a user data area Ub2 and a system area Sb2. The first recording layer Lai has a user data area Uai and a system area Sai. The second recording layer Lbi has a user data area Ubi and a system area Sbi.

[0030] Within the user data area Ua1 (first recording layer La1), the track enclosed by the double dashed lines in the diagram is designated as track Ta1. Within the user data area Ub1 (second recording layer Lb1), the track located on the opposite side of track Ta1 is designated as track Tb1. In the user data area Ua2 (first recording layer La2), the track enclosed by the double dashed lines in the diagram is designated as track Tc1. In the user data area Ub2 (second recording layer Lb2), the track located on the opposite side of track Tc1 is designated as track Td1. Within the user data area Uai (first recording layer Lai), the track enclosed by the double dashed lines in the diagram is designated as track Te1. Within the user data area Ubi (second recording layer Lbi), the track located on the opposite side of track Te1 is designated as track Tf1. In this embodiment, tracks Ta1, Tb1, Tc1, Td1, Te1, and Tf1 are located in the same cylinder.

[0031] The head HD faces the disk DK. In this embodiment, one head HD faces each recording layer L of the disk DK. For example, head HD1 faces the first recording layer La1 of 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 disk DK1, writes data to the second recording layer Lb1, and reads data from the second recording layer Lb1.

[0032] Head HD3 faces the first recording layer La2 of disk DK2, writes data to the first recording layer La2, and reads data from the first recording layer La2. Head HD4 faces the second recording layer Lb2 of disk DK2, writes data to the second recording layer Lb2, and reads data from the second recording layer Lb2. Head HDj-1 faces the first recording layer Lai of disk DKi, writes data to the first recording layer Lai, and reads data from the first recording layer Lai. Head HDj faces the second recording layer Lbi of disk DKi, writes data to the second recording layer Lbi, and reads data from the second recording layer Lbi.

[0033] Figure 3 is a schematic diagram showing an example of the arrangement of multiple servo regions SV and multiple data regions DTR on a single disk DK according to this embodiment. As shown in Figure 3, in the radial direction d1 of the disk DK, the direction toward the outer circumference of the disk DK is referred to as the outward direction (outside), and the direction opposite to the outward direction is referred to as the inward direction (inside). In Figure 3, the user data area U is divided into an inner circumference area IR located in the inward direction, an outer circumference area OR located in the outward direction, and a middle circumference area MR located between the inner circumference area IR and the outer circumference area OR.

[0034] The disk DK has multiple servo regions SV and multiple data regions DTR. The multiple servo regions SV may, for example, extend radially in the radial direction of the disk DK and be discretely arranged at predetermined intervals in the circumferential direction. The multiple servo regions SV may, for example, extend linearly from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. The multiple servo regions SV may, for example, extend spirally from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. Alternatively, the multiple servo regions SV may, for example, be arranged in an island-like manner in the radial direction and discretely arranged at predetermined intervals in the circumferential direction.

[0035] Hereafter, a single servo region SV on a given track may be referred to as a "servo sector." Furthermore, a "servo region SV" may also be referred to as a "servo sector SV." A servo sector contains servo data. Hereafter, the "arrangement of several servo data that constitute a servo sector" may be referred to as a "servo pattern." Furthermore, the "servo data written to a servo sector" may also be referred to as a "servo sector."

[0036] Multiple data areas DTR are each positioned between multiple servo areas SV. For example, a data area DTR corresponds to the area between two consecutive servo areas SV in the circumferential direction. Hereinafter, one data area DTR in a given track may be referred to as a "data sector." Note that a "data area DTR" may also be referred to as a "data sector DTR." A data sector contains user data. Note that "user data written to a data sector" may also be referred to as a "data sector." A "data sector" may also be referred to as "user data." Furthermore, a "pattern composed of several data" may also be referred to as a "data pattern." In the example shown in Figure 3, the data pattern of a given track consists of multiple servo data (servo sectors) and multiple user data (data sectors).

[0037] The servo region SV has multiple zone servo regions ZSV, etc. In addition to the zone servo regions ZSV, the servo region SV may also include a region containing a gap (the circumferential positional difference between two zone servo regions), a region containing servo data, and a data region DTR, etc. The multiple zone servo regions ZSV are discretely arranged along the radial direction d1. Each of the multiple zone servo regions ZSV extends radially along d1.

[0038] A single zone servo area (servo area) ZSV on a given track may be referred to as a "zone servo sector" or "servo sector." Furthermore, a "zone servo area (servo area) ZSV" may also be referred to as a "zone servo sector ZSV" or "servo sector ZSV." The "servo data written to a zone servo sector" may also be referred to as a "zone servo sector" or "servo sector." Hereafter, the "arrangement of several servo data that constitute a zone servo sector" may be referred to as a "zone servo pattern" or "servo pattern." Hereafter, a single servo area SV on a given track may also be referred to as a "zone pattern sector."

[0039] Note that the “servo area SV” may also be referred to as the “zone pattern sector.” The “at least one piece of data written to the zone pattern sector” may also be referred to as the “zone pattern sector.” A zone pattern sector includes at least one zone servo sector. Hereinafter, the “data pattern of the zone pattern sector” may also be referred to as the “zone data pattern.”

[0040] In the example shown in Figure 3, the servo region SV has zone servo regions ZSV0, ZSV1, and ZSV2. The zone servo regions ZSV0, ZSV1, and ZSV2 are arranged in a staggered pattern in the radial direction. The zone servo regions ZSV0, ZSV1, and ZSV2 may also be arranged in a stepped pattern in the radial direction.

[0041] Zone servo region ZSV2 is located on the inner circumference side of zone servo region ZSV1. Zone servo region ZSV0 is located on the outer circumference side of zone servo region ZSV1. For example, zone servo region ZSV2 is arranged from the inner circumference region IR to the middle circumference region MR, zone servo region ZSV1 is arranged from the inner circumference region IR to the outer circumference region OR, and zone servo region ZSV0 is arranged from the middle circumference region MR to the outer circumference region OR. Hereinafter, in a given servo region SV, a predetermined radial region in which multiple zone servo regions ZSV are arranged in the circumferential direction may be referred to as a zone servo boundary region, a double servo region, or a double zone servo region ZB.

[0042] In the example shown in Figure 3, the main servo region SVO and the secondary servo region SVE are arranged alternately with spacing in the circumferential direction. For example, one secondary servo region SVE is placed between two main servo regions SVO that are spaced apart and arranged consecutively in the circumferential direction. In other words, one secondary servo region SVE is placed between two main servo regions SVO that are spaced apart and arranged consecutively in the circumferential direction. For example, if all servo regions SV of disk DK are assigned sequential numbers, the main 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. Note that two or more secondary servo regions SVE may be placed between two main servo regions SVO that are spaced apart and arranged consecutively in the circumferential direction.

[0043] The main servo region SVO and the secondary servo region SVE may consist, for example, only of a servo region that reads and demodulates servo data overall (hereinafter sometimes referred to as the normal servo region). Hereinafter, "reading and demodulating servo data" may be referred to as "servo reading". The main servo region SVO and the secondary servo region SVE may consist, for example, of a normal servo region and a servo region that servo reads a range of servo data in the circumferential direction that is smaller than the range of servo data read in the normal servo region (hereinafter sometimes referred to as the short servo region).

[0044] The media cache M is allocated to disk DK. However, the media cache M does not necessarily have to be located on disk DK. By using the multiple servo data mentioned above, it is possible to derive, for example, the positioning error of the head HD (e.g., the light head WHD).

[0045] In this embodiment, the case where the disk DK has 3 zones was described as an example, but the number of zones in the disk DK can be changed in various ways. The number of zones in the disk DK may be 30 to 40. Furthermore, each zone has multiple bands. For example, each zone may have several hundred bands.

[0046] Figure 4 is a schematic diagram showing the three tracks STR of the user data area U where the tile recording process of disk DK shown in Figure 3 takes place, and the write head WHD. The user data area U is a tile recording area. Within the user data area U, sequential writing of data on a band-by-band basis is permitted; in other words, tile recording is permitted.

[0047] As shown in Figure 4, the write head WHD can sequentially write data to disk DK in the direction of travel d2. The read head RHD shown in Figure 3 can also sequentially read data written to disk DK in the direction of travel d2.

[0048] In a direction parallel to the radial direction d1, the direction in which multiple data tracks, or multiple track STRs, are recorded consecutively, that is, the direction in which the next track STR to be written is superimposed on the track STR that was written one step earlier in the radial direction d1, is called the overwriting direction or recording progress direction. In band BAe shown in Figure 4, the overwriting direction d5 is inward, but the overwriting direction may also be outward. For example, the overlay direction applied to multiple bands BA (multiple zones Z) located on the outer circumference side of a specific radial position may be opposite to the overlay direction applied to multiple bands BA (multiple zones Z) located on the inner circumference side of the specific radial position.

[0049] Band 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 writing direction d5 in the order they are described. Of tracks STRe, STRe+1, and STRe+2, track STRe is the track to which data is written first, and track STRe+2 is the track to which data is written last.

[0050] Track STRe has a track center STCe at the center of radial d1 when no other tracks are overlapping it. Track STRe+1 has a track center STCe+1 at the center of radial d1 when no other tracks are overlapping it. Track STRe+2 has a track center STCe+2 at the center of radial d1 when no other tracks are overlapping it.

[0051] In the example shown in Figure 4, tracks STRe, STRe+1, and STRe+2 are lit with a pitch (tile recording track pitch) STP. The track center STCe of track STRe and the track center STCe+1 of track STRe+1 are separated by a pitch STP in the radial direction d1. The track center STCe+1 of track STRe+1 and the track center STCe+2 of track STRe+2 are separated by a pitch STP in the radial direction d1. Tracks STRe through STRe+2 may be lit with different pitches.

[0052] The radial width d1 of the area within track STRe where track STRe+1 is not superimposed is the same as the radial width d1 of the area within track STRe+1 where track STRe+2 is not superimposed. However, the radial width d1 of the area within track STRe where track STRe+1 is not superimposed is different from the radial width d1 of the area within track STRe+1 where track STRe+2 is not superimposed.

[0053] In Figure 4, for the sake of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumference. Furthermore, each track STR may be wavy, extending circumferentially while fluctuating radially d1. Note that in Figure 4, three track STRs are superimposed, but two track STRs may be superimposed, or more than three track STRs may be superimposed.

[0054] The write processing unit 62 can select a tile recording format in which data is written to multiple tracks STR in the overlay direction d5 and cause the write head WHD to write data to each band BA. In the example shown in Figure 4, the write processing unit 62 sequentially records data to tracks STRe to STRe+2 in the band BAe with a pitch STP toward the inward direction (overlay direction d5). Since the user data area U is an area where data is written in the tile recording format, the recording density of the user data area U can be improved.

[0055] The light processing unit 62 lights track STre+1 inward of track STre with pitch STP, overwriting track STre+1 onto a portion of the inner circumference of track STre. The light processing unit 62 lights track STre+2 inward of track STre+1 with pitch STP, overwriting track STre+2 onto a portion of the inner circumference of track STre+1.

[0056] Figure 5 is a schematic diagram showing the three tracks CTR and the write head WHD of the media cache M where the normal recording process of disk DK shown in Figure 3 takes place. The media cache M and the system area S shown in Figure 3 are normal recording areas. Random data writing is permitted in the media cache M and system area S; in other words, normal recording is permitted.

[0057] As shown in Figure 5, the media cache M has multiple tracks CTR, including tracks CTRe, CTRe+1, and CTRe+2. Each of the multiple tracks CTR is a data track. For example, the radial width d1 (track width) of tracks CTRe, CTRe+1, and CTRe+2 is the same. However, the track widths of tracks CTRe to CTRe+2 may be different from each other.

[0058] Track CTRe has a track center CTCe at the center of radial d1, track CTRe+1 has a track center CTCe+1 at the center of radial d1, and track CTRe+2 has a track center CTCe+2 at the center of radial d1. In the example shown in Figure 5, tracks CTRe, CTRe+1, and CTRe+2 are written at pitch (normal recording track pitch) CTP. The track center CTCe of track CTRe and the track center CTCe+1 of track CTRe+1 are separated by pitch CTP. The track center CTCe+1 of track CTRe+1 and the track center CTCe+2 of track CTRe+2 are separated by pitch CTP.

[0059] Tracks CTRe and CTRe+1 are separated by a gap GP. Tracks CTRe+1 and CTRe+2 are separated by a gap GP. Tracks CTRe to CTRe+2 may be lit at different pitches. In Figure 5, for the sake of explanation, each track CTR is shown as a rectangle, but in reality, each track CTR is curved along the circumference. Furthermore, each track CTR may be wavy, extending circumferentially while fluctuating in the radial direction d1.

[0060] The write processing unit 62 can select a normal recording format in which data is written to multiple tracks CTR at intervals in the radial direction d1 of the disk DK and perform the write process. In the example shown in Figure 5, the write processing unit 62 positions the write head WHD on the track center CTCe in a predetermined area of ​​the disk DK and performs normal recording on track CTRe or a predetermined sector of track CTRe.

[0061] The write processing unit 62 positions the write head WHD at track center CTCe+1, which is located inward from track center CTCe of track CTRe by a pitch CTP, and normally records track CTRe+1 or a predetermined sector of track CTRe+1. The write processing unit 62 positions the write head WHD at track center CTCe+2, which is located inward from track center CTCe+1 of track CTRe+1 by a pitch CTP, and normally records track CTRe+2 or a predetermined sector of track CTRe+2.

[0062] The write processing unit 62 may sequentially record tracks CTRe, CTRe+1, and CTRe+2 in a predetermined area of ​​disk DK, or it may randomly record them in predetermined sectors of track CTRe, track CTRe+1, and track CTRe+2.

[0063] Figure 6 is a schematic diagram illustrating an example of data writing in disk DK. Tracks STR and CTR are data tracks, respectively. As shown in Figure 6, the user data area U has bands BAa, BAb, and BAc. Bands BAa, BAb, and BAc belong to the same zone Ze. In zone Ze, bands BAa, BAb, and BAc are arranged intermittently in the overlay direction in the order they are described.

[0064] Bands BAa and BAb are adjacent in the radial direction d1, and bands BAb and BAc are adjacent in the radial direction d1. Band BAa contains x tracks: STRa0, STRa1, STRa2, ..., STRa(x-3), STRa(x-2), and STRa(x-1). Tracks STRa0 through STRa(x-1) are recorded in the order listed above in the overwriting direction d5. In band BAa, track STRa0 corresponds to the first track on which data is written, and track STRa(x-1) corresponds to the last track on which data is written.

[0065] Band BAb contains x tracks: STRb0, STRb1, STRb2, ..., STRb(x-3), STRb(x-2), and STRb(x-1). Tracks STRb0 through STRb(x-1) are recorded in the order listed above in the overlay direction d5. In band BAb, track STRb0 corresponds to the first track on which data is written, and track STRb(x-1) corresponds to the last track on which data is written.

[0066] Band BAc contains x tracks: STRc0, STRc1, STRc2, ..., STRc(x-3), STRc(x-2), and STRc(x-1). Tracks STRc0 through STRc(x-1) are recorded in the order listed above in the overlay direction d5. In band BAc, track STRc0 corresponds to the first track on which data is written, and track STRc(x-1) corresponds to the last track on which data is written.

[0067] Each band BA belonging to the same zone Z has the same number of track STRs. For example, each band BA belonging to zone Ze has the same number of track STRs. In other words, the number of track STRs that each band BA has is fixed for each zone Z. In this example, each band BA belonging to zone Ze has x track STRs.

[0068] Figure 6 shows tracks CTR(x-2) and CTR(x-1). In Figure 6, 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.

[0069] Figure 7 is a schematic diagram showing two bands BAa and BAb and one guard band GB within the user data area U shown in Figure 6. As shown in Figure 7, unlike the normal recording method, the tile recording method has the characteristic of overwriting a portion of track STR, so the MPU60 manages the track groups of the user data area U in units called bands.

[0070] Generally, a guard band GB is provided between adjacent bands BA in the radial direction d1. The guard band GB includes a guard track GTR. Unlike this embodiment, the guard band GB may include multiple guard tracks GTR. The guard band GB plays a role in suppressing interference between adjacent bands BA. The guard band GB makes it possible to perform sequential recording in units of one band BA. In addition, the guard band GB makes it possible to separate the range (band BA) to be written sequentially.

[0071] For example, the track centers STCa(x-3) of track STRa(x-3), STCa(x-2) of track STRa(x-2), STCa(x-1) of track STRa(x-1), GTC of guard track GTR, STCb0 of track STRb0, STCb1 of track STRb1, and STCb2 of track STRb2 are all positioned at equal pitches in the overlapping direction d5.

[0072] With the exception of the guard band GB, the recording capacity of each band BA in the user data area U is usually predetermined based on the user's requirements. The MPU60 can record the same amount of data in each band BA. Generally, the recording capacity of each band BA is 128 MiB or 256 MiB.

[0073] Figure 8 is a schematic diagram showing three sectors SCe, SC(e+1), and SC(e+2) of track STRa0 in band BAa shown in Figure 6. As shown in Figure 8, each track STR has multiple sectors SC. Track STRa1 has multiple sectors SC, including sectors SCe, SC(e+1), and SC(e+2).

[0074] If we consider sector SC(e+1) as the nth sector among the multiple sectors SC of track STRa0, then sector SC(e+2) is the (n+1)th sector following sector SC(e+1) in the direction of travel d2, and sector SCe is the (n-1)th sector located before sector SC(e+1) in the direction of travel d2. Each track STR belonging to the same zone Z has the same number of sectors SC. In this embodiment, each track STR belonging to zone Ze has y sectors SC.

[0075] Each sector SC has a length Ls in the circumferential direction of disk DK. Each sector SC may also be a split sector, divided by a servo sector SV. In this case, the length of sector SC does not have to be Ls. The light head (WHD) is a magnetic head for energy-assisted magnetic recording (EAMR). In this embodiment, the light head (WHD) is configured to utilize energy other than magnetic energy, but it is not limited to this configuration; the light head (WHD) may be a magnetic head that is not configured to perform energy-assisted recording.

[0076] Figure 9 is a schematic diagram showing the two bands BAa and BAb shown in Figure 7, and one guard band GB, and is a diagram for explaining multiple target sectors RSC and multiple unused sectors VSC. In Figure 9, for illustrative purposes, each track STR is shown as a rectangle; however, in reality, each track STR is curved along the circumference. Also, while multiple track STRs are shown aligned in the overlapping direction d5 without overlapping, in reality, multiple track STRs overlap while aligned in the overlapping direction d5. Furthermore, in the figure, the target sector RSC is marked with a dot pattern. Unused sector VSC is represented as blank.

[0077] As shown in Figure 9, the band number of band BAa is denoted as "a" and the band number of band BAb is denoted as "b". The track numbers of each band BA are denoted as "0" to "x-1". The sector numbers of each track STR are denoted as "0" to "y-1". Hereafter, the sector SC of each band BA may be identified using the following code "SC(track number, sector number)".

[0078] In this embodiment, band BAa is a band adjacent to band BAb and is positioned above band BAb in the overlay direction d5. Each track STR in band BAa contains G target sector RSCs (one or more target sector RSCs) on which valid data has been written. For example, track STRa0 has y target sector RSCs (G=y). All sector SCs in track STRa0 are target sector RSCs. Track STRa(x-1) has 5 target sector RSCs (G=5). The remaining sector SCs in track STRa(x-1) are unused sector VSCs on which no valid data has been written. From the above, the number of target sector RSCs in track STRa0 is different from the number of target sector RSCs in track STRa(x-1).

[0079] In each band BA of Zone Ze, all sector SCs of the x-1 tracks STR from 0 to x-2 are target sector RSCs and recording sector USCs with valid data written to them. In the x-1 track STR of each band BA in Zone Ze, the five sector SCs from 0 to 4 are target sector RSCs and recording sector USCs. On the other hand, in the x-1 track STR, the remaining sector SCs from 5 to y-1 are unused sector VSCs with no valid data written to them.

[0080] Figure 10 is a schematic diagram showing an example of a first track STR0 and a second track STR1, assuming that the magnetic disk drive 1 does not have a function to perform error correction on the data of track TR. It is a diagram for explaining the write process to the first track STR0 and the second track STR1. It is a diagram for explaining the state in which the write process to the second track STR1 is continued until the sector-by-sector error correction for the first track STR0 reaches its limit. It is a diagram that shows the change in the bit error rate (BER) for the first track STR0 and the change in BER with respect to the position error (PE) as graphs. In the explanation using Figure 10, the magnetic disk drive 1 is described as not having the error correction unit 64 of Figure 1. Also, in Figure 10, for the sake of explanation, the first track STR0, etc. are drawn as if the circumferential direction is a straight line.

[0081] As shown in Figure 10, in the recording layer L, multiple tracks STR are adjacent in the radial direction d1. The first track STR0 and the second track STR1 are data tracks, adjacent to each other, and all sectors SC of the first track STR0 and all sectors (data sectors) SC of the second track STR1 are target sectors RSC, respectively. The write operation to the first track STR0 is performed ideally without positioning error PE (PE ≈ 0, or PE = 0).

[0082] If the magnetic disk drive 1 is affected by external vibrations during the write process, a positioning error PE occurs when positioning the write head WHD. The positioning error PE is the amount of deviation of the write head WHD from the target position in the radial direction d1. By setting the track margin TM, it is possible to determine the acceptable range within which it is guaranteed that data on adjacent tracks can be read.

[0083] For example, if a write operation is performed on the second track STR1, and the target sectors RSCe, RSC(e+1), and RSC(e+2) of the first track STR0 are adjacent to the light head WHD in the radial direction d1 during the period when the positioning error PE exceeds the track margin TM, then the data in target sectors RSCe, RSC(e+1), and RSC(e+2) of the first track STR0 is judged (expected) to be corrupted. A lower BER for the data is desirable, but the BER of the data in target sectors RSCe, RSC(e+1), and RSC(e+2) of the first track STR0 exceeds the threshold BERTH. As can be seen from the graph on the right side of Figure 10, the larger the positioning error PE, the greater the adverse effect of ATI (Adjacent Track Interference), and the BER of the data in the first track STR0, which is excessively affected by the adverse effect of ATI, becomes excessively high.

[0084] Therefore, among the multiple target sector RSCs of the first track STR0, target sector RSCe, target sector RSC(e+1), and target sector RSC(e+2) are determined to be corrupted sector CSC1, target sector CSC2, and target sector CSC3. This can lead to a deterioration in the quality of the signal obtained by reading the data from corrupted sectors CSC1 to CSC3, or the erasure of the data from corrupted sectors CSC1 to CSC3.

[0085] In the example explained using Figure 10, the magnetic disk drive 1 does not have the function to perform track-level error correction on the data of track TR. Here, track-level error correction is also called track ECC (Error Checking and Correcting). Therefore, target sectors RSCe, RSC(e+1), and RSC(e+2) remain as corrupted sectors CSC1, CSC2, and CSC3.

[0086] Here, in Figure 10, it is assumed that all target sector RSCs of track TR have a common track margin TM. In the explanations of Figures 11 and 12 described later, it is also assumed that all target sector RSCs of track TR have a common track margin TM. However, the above setting of track margin TM is just an example, and the track margin TM may be different for each target sector RSC.

[0087] Figure 11 is a schematic diagram showing an example of a first track STR0 and a second track STR1, assuming that the magnetic disk drive 1 does not have a function to perform track-level error correction on the data of track TR. It is a diagram for explaining the write process for the first track STR0 and the second track STR1. It is a diagram for explaining the state in which the write process for the second track STR1 is terminated when the judgment value is set to a write-off track slice WOS that is smaller (stricter) than the track margin TM and the positioning error PE is detected to have exceeded the reference radius position PO. It is a diagram that shows the change in BER for the first track STR0 and the change in BER for the positioning error PE, respectively, as graphs. In Figure 11, for the sake of explanation, the first track STR0, etc., are drawn as if the circumferential direction is a straight line. In the explanation using Figure 11, the magnetic disk drive 1 is described as not having the error correction unit 64 of Figure 1.

[0088] As shown in Figure 11, the first track STR0 and the second track STR1 are data tracks, and all sectors SC of the first track STR0 and all sectors (data sectors) SC of the second track STR1 are target sectors RSC, respectively. The write operation to the first track STR0 is performed ideally without positioning error PE (PE ≈ 0, or PE = 0). The first track STR0 is located in a first direction Da parallel to the radial direction d1 when viewed from the second track STR1. The write processing unit 62 can select a recording format in which the data of the second track STR1 is written over the data of the first track STR0 in the overwriting direction d5, which is opposite to the first direction Da.

[0089] In order to prevent or suppress the write process in a state where the positioning error PE exceeds the track margin TM, the magnetic disk device 1 has a write-off track slice WOS. The reference radius position PO is a position offset by the write-off track slice WOS in the first direction Da from the track center STC1 of the second track STR1. When it is determined that the positioning error PE exceeds the reference radius position PO during the period of writing data to the second track STR1, the writing of data to the second track STR1 can be paused. Among the plurality of target sectors RSC of the second track STR1, the remaining target sectors RSC for which the writing of data has been postponed become empty sectors ESC where no data has been written. By avoiding a situation where the positioning error PE exceeds the track margin TM, the occurrence of damaged target sectors CSC in the first track STR0 can be prevented.

[0090] Note that the track STR has servo sectors in addition to the sector SC which is a data sector. In the track STR, generally, the data sectors and the servo sectors are arranged alternately. The head HD (read head RHD) can derive the positioning error PE together with the servo sectors. Therefore, generally, the positioning error PE is information obtained intermittently.

[0091] In order for PE > TM not to occur, it is necessary to set the write-off track slice WOS so that WOS ≤ TM. In order to avoid a situation where PE > TM, it is desirable to set the write-off track slice WOS so that WOS < TM. Thereby, before the positioning error PE exceeds the track margin TM, the write process for the second track STR1 can be paused, and a situation where the quality of the data in the first track STR0 deteriorates can be avoided.

[0092] However, it should be noted that setting the write-off track slice WOS to a small value makes write operations more likely to be interrupted, leading to a decrease in the write performance of the magnetic disk drive 1. In the case of the magnetic disk drive 1, which does not have a function to perform track-level error correction, if write operations to the second track STR1 are interrupted, a write retry process is executed, which waits for the disk DK to rotate until PE ≤ WOS before resuming write operations to the second track STR1. The write retry process allows the free sector ESC of the second track STR1 to be changed to the recording sector USC, thus avoiding a situation where the utilization efficiency of the second track STR1 remains low.

[0093] Here, in Figure 11, it is assumed that all target sector RSCs of track TR have a common write-off track slice WOS. In the explanation of Figure 12, which will be described later, it is also assumed that all target sector RSCs of track TR have a common write-off track slice WOS. However, the above setting of the write-off track slice WOS is just an example, and the write-off track slice WOS may be different for each target sector RSC.

[0094] Figure 12 is a schematic diagram showing an example of a first track STR0 and second track STR1 of a magnetic disk drive 1 that has a function to perform track-level error correction on the data of track TR. It is a diagram to explain the write process for the first track STR0 and second track STR1. It is a diagram to explain a state in which the write-off track slice WOS is set to a value greater than (looser than) the track margin TM, and the write process for the second track STR1 is continued until the track-level error correction for the first track STR0 reaches its limit. The diagram shows the change in BER for the first track STR0 and the change in BER for the positioning error PE, respectively, as graphs. In Figure 12, for the sake of explanation, the first track STR0, etc., are drawn as if the circumferential direction is a straight line.

[0095] As shown in Figure 12, the light operation on the first track STR0 is performed ideally without positioning error PE (PE ≈ 0, or PE = 0). The magnetic disk device 1 is equipped with an error correction unit 64. When a corrupted sector CSC occurs on track ST, the read processing unit 63, together with the head amplifier IC 130, can detect that a corrupted sector CSC has occurred on track ST, and the error correction unit 64 can perform error correction processing to recover the data of the corrupted sector CSC. For example, if a corrupted sector CSC occurs on the first track STR0, the error correction unit 64 can recover the data of the corrupted sector CSC based on the user data of multiple target sector RSCs on the first track STR0 and the parity of the parity sector.

[0096] The above parity sector is generated based on user data of multiple target sector RSCs of the first track STR0, and can be provided in a portion of the multiple target sector RSCs of the first track STR0. For example, one or two target sector RSCs of the first track STR0 can be used as the parity sector. However, the above parity sector may be provided in a track TR other than the first track STR0. Alternatively, the above parity sector may be provided in memory other than disk (for example, non-volatile memory 90).

[0097] As described above, even if a corrupted sector CSC occurs on the first track STR0, the error correction unit 64 can perform error correction processing to recover the data of the corrupted sector CSC, thus allowing the occurrence of a corrupted sector CSC on the first track STR0 to be tolerated. In a magnetic disk device 1 equipped with an error correction unit 64, the write-off track slice WOS can be set such that WOS ≥ TM.

[0098] It should be noted that there is an upper limit on the number of corrupted sectors that the error correction unit 64 can perform error correction on a track-by-track basis. For example, if the number of corrupted sectors CSC on the first track STR0 exceeds the upper limit (e.g., 12), it will be difficult for the error correction unit 64 to recover the data from all of the corrupted sectors CSC.

[0099] Figure 13 is a table showing the presence or absence of track ECC, the function name for controlling DOL, the processing when the positioning error PE exceeds the reference radius position PO, the settings for overwriting data in buffer memory 80, and the settings for saving data in buffer memory 80 in the first and second methods of the first and second light operation.

[0100] As shown in Figures 13, 11, and 1, assuming that the magnetic disk drive 1 does not have a track ECC function, the magnetic disk drive 1 can employ a first write operation. The function name for controlling the DOL (Drift-Off Level) is DDOL (Dynamic Drift-Off Level). The first write operation corresponds to the write operation shown using Figure 11.

[0101] If, during the first write period while performing write operations on the second track STR1, the positioning error PE exceeds the reference radius position PO, the write operation on the second track STR1 is paused before the positioning error PE exceeds the track margin TM. Subsequently, a write retry process is executed, which waits for disk DK to rotate until PE ≤ WOS, and then resumes the write operation on the second track STR1.

[0102] However, if the magnetic disk drive 1 employs the first write operation, write retry processes such as waiting for disk DK to rotate may occur frequently, making it difficult to improve the write performance of the magnetic disk drive 1. Therefore, in order to improve the write performance of the magnetic disk drive 1, the magnetic disk drive 1 employing the second write operation has a track ECC function. In the magnetic disk drive 1 employing the second write operation, the function name for controlling DOL is iDDOL (intelligence Dynamic Drift-Off Level). This allows for a certain number of corrupted sectors (CSCs) to occur in the track STR, improving TPI (Tracks Per Inch).

[0103] (Second method of operation for the second light) Next, we will explain the second method of operation for the second light. As shown in Figures 13, 1, and 12, the error correction unit 64 can perform error correction on the data of one or more corrupted target sectors CSC among the multiple target sectors RSC of the first track STR0 that are determined to have corrupted data.

[0104] The buffer memory 80 is capable of holding multiple data, including first user data and second user data. The management unit 65 can selectively execute a first management that prohibits overwriting of the first user data in the buffer memory 80, a second management that permits overwriting of all of the first user data in the buffer memory 80, and a third management that permits overwriting of data belonging to the first group and the second group of the first user data in the buffer memory 80, while prohibiting overwriting of data belonging to the third group of the first user data in the buffer memory 80.

[0105] Here, we focus on the first write period, which is the period after the write processing unit 62 has performed a write operation to write first data including first user data to multiple target sector RSCs of the first track STR0, and during which it performs a write operation to write second data including second user data to multiple target sector RSCs of the second track STR1.

[0106] During the first write period, the read processing unit 63 performs a seek operation to seek the read head RHD, and positions the write head WHD opposite the second track STR1. The correction limit determination unit 66 acquires information that the position of the light head WHD extends beyond the reference radius position PO in the first direction Da each time data is written to each target sector RSC of the second track STR1. The management unit 65 performs the above-mentioned first management. Based on the information acquired by the correction limit determination unit 66, if the judgment unit 67 determines that the error correction of the first user data on the first track STR0 by the error correction unit 64 has not exceeded the limit, it can cause the write processing unit 62 to continue writing to the second track STR1 and cause the management unit 65 to perform the second management instead of the first management. Since it is no longer necessary to keep the first user data in the buffer memory 80, it becomes possible to allow data overwriting of the first user data in the buffer memory 80, and the amount of new data that the buffer memory 80 can receive can be increased.

[0107] Furthermore, if the judgment unit 67 determines, based on the above information, that the error correction of the first user data on the first track STR0 by the error correction unit 64 has exceeded its limit, it can cause the write processing unit 62 to continue writing to the second track STR1, and cause the management unit 65 to perform the third management instead of the first management. Then, during or after the first write period, the determination unit 67 can instruct the management unit 65 to save the data belonging to the third group as a non-volatile recording medium, for example, in the system area S of the recording layer L of disk DK. The data saved in the system area S can be permanently stored in the system area S.

[0108] Furthermore, the data belonging to the first group of first user data in buffer memory 80 is the original data of one or more target sector RSCs in the first track STR0 that were determined not to be corrupted. The data belonging to the second group of first user data in buffer memory 80 is the original data of one or more first corrupted target sectors CSC of the first track STR0 that have been determined to be corrupted, and is the original data of data within the range that can be corrected by the error correction unit 64. The data belonging to the third group of first user data in buffer memory 80 is the original data of one or more second corrupted target sectors CSC of the first track STR0 that were determined to be corrupted, and is also the original data of data that was missed from the range in which error correction by the error correction unit 64 is possible.

[0109] Even if the error correction by the error correction unit 64 exceeds its limit, the write process to the second track STR1 can continue. Therefore, a decrease in write performance can be suppressed. Furthermore, for the corrupted data on the first track STR0, the excess corrupted data exceeding the limits of error correction by the error correction unit 64 can be saved from the buffer memory 80 to the system area S. This indirectly guarantees the integrity of the excess corrupted data on the first track STR0. The error correction unit 64 can use the first user data and first parity on the first track STR0, along with the original data saved in the system area S, to perform error correction processing to recover the data of all corrupted sectors CSC on the first track STR0. Since the quality of the data on the first track STR0 can be improved, it is possible to avoid a situation where the signal quality obtained by reading the data on the first track STR0 remains in a degraded state.

[0110] On the other hand, if the first method of the second write operation is adopted, the error correction unit 64 cannot tolerate situations where error correction exceeds its limits. This may increase the frequency of pausing (or terminating) the write operation to the second track STR1. Furthermore, if the write operation is terminated, this may increase the frequency of activating PTS (Partial Track Slip), which saves the remaining data that could not be written to the second track STR1. The first method of the second write operation is unlikely to contribute to improving the write performance of the magnetic disk device 1.

[0111] Next, we adopt the second method of the second write operation and focus on the first track STR0 and the second track STR1 after the write process for the first track STR0 and the second track STR1 has been completed.

[0112] The first user data is written to all target sector RSCs on the first track STR0. Or, both the first user data and the first parity generated based on the first user data are written to all target sector RSCs on the first track STR0. Second user data is written to all target sector RSCs on track STR1. Or, both second user data and second parity generated based on the second user data are written to all target sector RSCs on track STR1.

[0113] In the second method of the second write operation, since PTS is not activated, the target sector RSC of the first track STR0 and the second track STR1 does not become an empty sector ESC. Therefore, the utilization efficiency of the first track STR0 and the second track STR1 can be increased.

[0114] Next, we will explain the case where the information acquired by the correction limit determination unit 66 is the cumulative measured excess amount, which is the sum of the measured excess amounts where the positioning error PE extends beyond the reference radius position PO in the first direction Da.

[0115] Each time the second data is written to the target sector RSC of the second track STR1, the correction limit determination unit 66 measures the actual excess amount by which the position of the light head WHD extends beyond the reference radius position PO in the first direction Da, and updates the cumulative actual excess amount, which is the sum of the actual excess amounts. The information acquired by the correction limit determination unit 66 is the cumulative actual excess amount. During the first write period, if the determination unit 67 determines that the cumulative measured excess amount is less than or equal to the upper limit threshold, it can cause the write processing unit 62 to continue writing to the second track STR1 and cause the management unit 65 to perform the second management instead of the first management. Here, the upper limit threshold is a value that indicates the limit of the range in which error correction is possible for the first track STR0.

[0116] During the first write period, if the determination unit 67 determines that the cumulative measured excess amount exceeds the upper limit threshold, it can cause the write processing unit 62 to continue writing to the second track STR1, and the management unit 65 to perform the third management instead of the first management, and the correction limit determination unit 66 to update the cumulative measured excess amount by subtracting the measured excess amount measured each time one or more second damaged target sectors CSC are formed on the first track STR0 from the cumulative measured excess amount.

[0117] The determination unit 67 can determine whether to allow or prohibit overwriting the original data in the buffer memory 80 based on the relationship between the cumulative measured excess amount and the upper limit threshold, and can also determine whether it is necessary to save the original data from the buffer memory 80 to the system area S.

[0118] When the determination unit 67 saves the original data from the buffer memory 80 to the system area S, it is preferable to save the original data of the most corrupted data among the first track STR0 as a priority. This is because the cumulative measured excess amount can be updated to the smallest amount, making it less likely for the cumulative measured excess amount to exceed the upper threshold. In that case, the second measured excess amount is greater than or equal to the first measured excess amount. Here, the first measured excess amount is the amount when one or more first damaged sector CSCs are formed on the first track STR0. Also, the second measured excess amount is the amount when one or more second damaged sector CSCs are formed on the first track STR0.

[0119] Next, we will explain the case where the information acquired by the correction limit determination unit 66 is the cumulative number, which is the total number of damaged sector CSCs. The correction limit determination unit 66 can count the number of one or more damaged sector CSCs in the first track STR0 and update the cumulative number, which is the sum of the above counts. The information acquired by the correction limit determination unit 66 is the cumulative number.

[0120] During the first write period, if the determination unit 67 determines that the cumulative number is less than or equal to the upper limit, it can instruct the write processing unit 62 to continue writing to the second track STR1, and the management unit 65 to perform the second management instead of the first management. Here, the upper limit is the number that indicates the limit of the range in which error correction is possible for the first track STR0.

[0121] During the first write period, if the determination unit 67 determines that the cumulative number has exceeded the upper limit, it can cause the write processing unit 62 to continue writing to the second track STR1, and the management unit 65 to perform the third management instead of the first management, and the correction limit determination unit 66 to update the cumulative number by subtracting the number of second corrupted target sectors CSC, which is counted each time one or more second corrupted target sectors CSC are formed on the first track STR0, from the cumulative number each time.

[0122] If the cumulative number exceeds the upper limit, the total number of first corrupted sectors (CSCs) (one or more) will match the upper limit. The determination unit 67 can determine whether to allow or prohibit overwriting the original data in the buffer memory 80 based on the relationship between the cumulative number and the upper limit, and can also determine whether it is necessary to save the original data from the buffer memory 80 to the system area S.

[0123] Next, we will explain the case where the information acquired by the correction limit determination unit 66 includes both the cumulative measured excess amount and the cumulative number. During the first write period, if the determination unit 67 determines that the cumulative measured excess amount is less than or equal to the upper limit threshold and that the cumulative number is less than or equal to the upper limit number, it can instruct the write processing unit 62 to continue writing to the second track STR1 and the management unit 65 to perform the second management instead of the first management.

[0124] During the first write period, if the determination unit 67 determines that the cumulative measured excess amount exceeds the upper limit threshold, it can cause the write processing unit 62 to continue writing to the second track STR1, and the management unit 65 to perform the third management instead of the first management, and the correction limit determination unit 66 to update the cumulative measured excess amount by subtracting the measured excess amount measured each time one or more second damaged target sectors CSC are formed on the first track STR0 from the cumulative measured excess amount.

[0125] During the first write period, if the determination unit 67 determines that the cumulative number has exceeded the upper limit, it can cause the write processing unit 62 to continue writing to the second track STR1, and the management unit 65 to perform the third management instead of the first management, and the correction limit determination unit 66 to update the cumulative number by subtracting the number of second corrupted target sectors CSC, which is counted each time one or more second corrupted target sectors CSC are formed on the first track STR0, from the cumulative number each time.

[0126] Next, we will describe the non-volatile recording medium that serves as the backup location for the original data in buffer memory 80. The first track STR0 and the second track STR1 are located in the user data area U of the recording layer L. The non-volatile recording medium may be, for example, a system area S of the recording layer L that is different from the user data area U.

[0127] Here, among the multiple bands BA, the band containing the first track STR0 and the second track STR1 is defined as the first band BA. In order for the management unit 65 to save the data belonging to the third group to the system area S, it is necessary to use the write head WHD.

[0128] The timing for the management unit 65 to save the data belonging to the third group to the system area S is after the write process of writing the second data to multiple target sectors RSC on the second track STR1 is completed (after the first write period). Alternatively, the timing for the management unit 65 to save the data belonging to the third group to the system area S may be after the write process for writing data to multiple tracks STR of the first band BA has been completed (after the first write period).

[0129] The non-volatile recording medium may be, for example, the non-volatile memory 90 outside the disk DK. In that case, the timing for the management unit 65 to save the data belonging to the third group to the non-volatile memory 90 can be considered to be after the timing when it determines that the error correction of the first user data on the first track STR0 has exceeded its limit (midway through the first write period). This is because the write operation to the second track STR1 and the save operation to the non-volatile memory 90 can be performed simultaneously.

[0130] Alternatively, the timing for the management unit 65 to save the data belonging to the third group to the non-volatile memory 90 may be after the write process for writing the second data to multiple target sectors RSC of the second track STR1 has been completed (after the first write period). Alternatively, the timing for the management unit 65 to save the data belonging to the third group to the non-volatile memory 90 can be after the write process for writing data to multiple tracks STR of the first band BA has been completed (after the first write period).

[0131] (Example of the first method of operation of the second light) Next, the first method of the second write operation will be explained exemplified. Figure 14 shows the change in positioning error PE and the change in the cumulative number of damaged sectors CSC when a write operation is performed on the second track STR1 using the first method of the second write operation. This figure shows the case when the cumulative number exceeds the PTS activation threshold during the write operation to the nth target sector RSCn of the second track STR1.

[0132] As shown in Figure 14, multiple target sectors RSC (data area DTR) and multiple servo sectors SSC (servo area SV) are arranged in the circumferential direction. Each time 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 an effective process when the head HD becomes oscillating due to the effects of seek operations, etc. However, the proportion (size) of the servo sector SSC in the track STR is smaller than the proportion (size) of the target sector RSC in the track STR. Therefore, it is difficult to sufficiently correct the position of the head HD in the radial direction d1.

[0133] Therefore, when write operations are performed on multiple target sectors RSC of the second track STR1, the positioning error PE may exceed the reference radius position PO multiple times. The determination unit 67 can determine whether to activate PTS by monitoring whether the cumulative number of damaged target sectors CSC of the first track STR0 exceeds the PTS activation threshold.

[0134] In the example in Figure 14, we focus on the point when the write processing unit 62 has performed write processing up to the nth target sector RSCn of the second track STR1. At this point, it can be seen that the cumulative number has exceeded the PTS activation threshold. The determination unit 67 can activate the PTS. That is, the determination unit 67 does not perform write processing for target sector RSC(n+1) and subsequent target sector RSCs of the second track STR1, and saves the remaining data that could not be written to the second track STR1 to tracks other than the first track STR0 and the second track STR1.

[0135] The reason why write operations cannot be performed on target sector RSC of the second track STR1 from the (n+1)th target sector RSC(n+1) onward is that the error correction unit 64 cannot tolerate a situation where error correction exceeds its limits. As described above, the first method of the second write operation is unlikely to contribute to improving the write performance of the magnetic disk device 1.

[0136] (Example of the second method of the second light operation) (Information: Cumulative number) Next, the second method of the second write operation will be explained exemplified. Figure 15 shows the change in positioning error PE and the change in the cumulative number of damaged sectors CSC when a write operation is performed on the second track STR1 using the second method of the second write operation. This figure shows the case when the cumulative number exceeds the upper limit when writing to the nth target sector RSCn of the second track STR1. Here, the information acquired by the correction limit determination unit 66 is the cumulative number.

[0137] As shown in Figure 15, the determination unit 67 monitors whether the cumulative number of damaged sectors CSC on the first track STR0 exceeds the upper limit, and can then determine whether to have the management unit 65 execute one of the first, second, or third management processes.

[0138] In the example shown in Figure 15, we focus on the point when the write processing unit 62 has performed write processing up to the nth target sector RSCn of the second track STR1. At this point, it can be seen that the cumulative number has exceeded the upper limit. Even if the cumulative number exceeds the upper limit, the determination unit 67 can allow the write processing unit 62 to continue writing to the second track STR1, thereby suppressing a decrease in write performance.

[0139] Furthermore, the judgment unit 67 causes the management unit 65 to perform the third management, thereby causing the correction limit determination unit 66 to subtract the number of second damaged target sectors CSC from the cumulative number and update the cumulative number. In other words, in Figure 15, the cumulative number can be updated from the state shown by the dashed line to the state shown by the solid line. As a result, it is possible to maintain a state in which the track-level error correction for the first track STR0 does not reach its limit.

[0140] (Example of the second method of the second light operation) (Information: Cumulative measured excess amount) Next, the second method of the second write operation will be explained exemplified. Figure 16 shows the change in positioning error PE and the change in cumulative measured excess amount when a write operation is performed on the second track STR1 using the second method of the second write operation. This figure shows the case when the cumulative measured excess amount exceeds the upper limit threshold during the write operation to the nth target sector RSCn of the second track STR1. Here, the information acquired by the correction limit determination unit 66 is the cumulative measured excess amount.

[0141] As shown in Figure 16, the determination unit 67 monitors whether the cumulative measured excess amount for the damaged sector CSC of the first track STR0 exceeds the upper limit threshold, and can then determine whether to have the management unit 65 execute the first to third management.

[0142] In the example in Figure 16, we focus on the point when the write processing unit 62 has performed write processing up to the nth target sector RSCn of the second track STR1. At this point, it can be seen that the cumulative measured excess amount has exceeded the upper limit threshold. Even if the cumulative measured excess amount exceeds the upper limit threshold, the determination unit 67 can allow the write processing unit 62 to continue writing to the second track STR1, thereby suppressing a decrease in write performance.

[0143] Furthermore, the judgment unit 67 causes the management unit 65 to perform the third management, thereby causing the correction limit determination unit 66 to subtract the measured excess amount from the cumulative measured excess amount and update the cumulative measured excess amount. In other words, in Figure 16, the cumulative measured excess amount can be updated from the state shown by the dashed line to the state shown by the solid line. As a result, it is possible to maintain a state in which the error correction on a track-by-track basis for the first track STR0 does not reach its limit.

[0144] Here, we note that within the period during which write operations were performed on target sectors RSC0 (the 0th target sector) to RSCn (the nth target sector) of the second track STR1, the measured excess amount was maximized when the write operation was performed on target sector RSCα (the αth target sector).

[0145] When the determination unit 67 saves the original data from the buffer memory 80 to the system area S, it can prioritize saving the original data of the most damaged target sector RSCα on the first track STR0 to the system area S. In this case, the correction limit determination unit 66 can subtract the actual excess amount during the write operation for the target sector RSCα on the second track STR1 from the cumulative actual excess amount and update the cumulative actual excess amount. Since the cumulative actual excess amount can be updated to the smallest amount, the cumulative actual excess amount becomes less likely to exceed the upper limit threshold.

[0146] Next, a second method of the second write operation will be illustrated using a flowchart. Figure 17 is a flowchart showing the write processing method for the nth target sector RSCn of the second track STR1 according to this embodiment, and is a diagram showing the case when the magnetic disk device 1 adopts the second method of the second write operation during the first write period. Figure 18 is a flowchart of the write processing method following Figure 17.

[0147] As shown in Figures 17, 1, and 12, when the second method of the second write operation is started, first, in step ST1a, the write processing unit 62 executes a write operation to write the first data, which includes the first user data, to the first track STR0. Subsequently, in step ST2a, the management unit 65 executes a first management operation to prohibit overwriting the first user data in the buffer memory 80. After that, in step ST3a, the write processing unit 62 executes a write operation to write the second data, which includes the second user data, to the second track STR1.

[0148] In step ST4a, during the write operation to write data to the nth target sector RSCn of the second track STR1, the positioning error PE exceeded the reference radius position PO. Subsequently, in step ST5a, the determination unit 67 determines, based on the information acquired by the correction limit determination unit 66, whether the error correction of the first user data on the first track STR0 has exceeded the limit.

[0149] As shown in Figures 18, 1, and 12, if the error correction of the first user data on the first track STR0 exceeds the limit (step ST5a, YES), the process proceeds to step ST6a, where the determination unit 67 saves the original data of one of the multiple corrupted sector CSCs on the first track STR0 from the buffer memory 80 to a recording medium (e.g., system area S), and proceeds to step ST7a. On the other hand, if the error correction of the first user data on the first track STR0 does not exceed the limit (step ST5a, NO), the process proceeds to step ST7a.

[0150] In step ST7a, the determination unit 67 determines whether the nth target sector RSCn of the second track STR1 is the final target sector RSC on the second track STR1 to which the second user data is written. If the nth target sector RSCn of the second track STR1 is the final target sector RSC (step ST7a, YES), the process proceeds to step ST8a, where the write processing unit 62 executes a write operation to write the second parity of the second data to the (n+1)th target sector RSC(n+1) of the second track STR1. The write operation for the first track STR0 and the second track STR1 is completed when the writing of the second parity to the second track STR1 is finished.

[0151] On the other hand, if the nth target sector RSCn of the second track STR1 is not the last target sector RSC (step ST7a, NO), the process proceeds to step ST9a, and the write processing unit 62 executes a write operation to write data to the (n+1)th target sector RSC(n+1) of the second track STR1. That is, the write processing unit 62 continues the write operation to write the second user data to the second track STR1. The write operation to the first track STR0 and the second track STR1 is completed when the writing of the second user data and the second parity to the second track STR1 is finished.

[0152] Step ST6a in Figure 18 is modifiable. Figure 19 is a modified version of the flowchart showing the light processing method, following Figure 17. As shown in Figures 19, 1, and 12, step ST6a in Figure 18 can be replaced with step ST6b in Figure 19. Note that in Figure 19, everything except step ST6b is the same as in Figure 18.

[0153] In step ST6b, the determination unit 67 may save the original data of the corrupted target sector CSC, which has the most corrupted data among the 0th target sector RSC0 to the nth target sector RSCn of the first track STR0, from the buffer memory 80 to the recording medium (for example, the system area S), and proceed to step ST7a.

[0154] According to the magnetic disk device 1 configured as described above, the magnetic disk device 1 comprises a disk DK, a head HD, a read processing unit 63, a write processing unit 62, an error correction unit 64, a buffer memory 80, a management unit 65, a correction limit determination unit 66, and a determination unit 67.

[0155] During the first write period, the read processing unit 63 performs a seek operation to move the read head RHD, and positions the write head WHD opposite the second track STR1. The correction limit determination unit 66 acquires information that the position of the write head WHD extends beyond the reference radius position PO in the first direction Da each time data is written to each target sector RSC of the second track STR1. The management unit 65 performs the first management.

[0156] If the judgment unit 67 determines, based on the information acquired by the correction limit determination unit 66, that the error correction of the first user data on the first track STR0 by the error correction unit 64 has not exceeded its limit, it can instruct the write processing unit 62 to continue writing to the second track STR1 and the management unit 65 to perform the second management instead of the first management. If the judgment unit 67 determines, based on the above information, that the error correction of the first user data on the first track STR0 by the error correction unit 64 has exceeded its limit, it can instruct the write processing unit 62 to continue writing to the second track STR1 and the management unit 65 to perform the third management instead of the first management. Then, during or after the first write period, the determination unit 67 can cause the management unit 65 to perform a process to save the data belonging to the third group to a non-volatile recording medium.

[0157] This avoids situations where the write process to the second track STR1 is paused or terminated, thereby contributing to an improvement in the write performance of the magnetic disk drive 1. Furthermore, unlike when PTS is activated, it eliminates the need to read separated data while performing seek operations, thus contributing to improved read performance.

[0158] Furthermore, because PTS is not activated, the target sector RSC of the first track STR0 and the second track STR1 do not become an empty sector ESC. Therefore, the utilization efficiency of the first track STR0 and the second track STR1 can be increased, and the data recording density (ADC: Areal Density Capability) on the disk DK can be improved.

[0159] Furthermore, with respect to the corrupted data on the first track STR0, the excess corrupted data exceeding the limits of error correction by the error correction unit 64 can be saved from the buffer memory 80 to the recording medium (for example, the system area S). This indirectly guarantees the safety of the excess corrupted data on the first track STR0. As described above, a magnetic disk device 1 can be obtained that can improve the recording density of data on the disk DK and suppress the deterioration of write performance.

[0160] Although the above embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The above novel embodiments can be implemented in various other forms, 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 in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0161] 1…Magnetic disk drive, 60…MPU, 61…Read / write processing unit, 62…Write processing unit, 63…Read processing unit, 64…Error correction unit, 65…Management unit, 66…Correction limit determination unit, 67…Decision unit, 70…Volatile memory, 80…Buffer memory, 90…Non-volatile memory, 100…Host, 110…System controller, 120…Driver IC, 130…Head amplifier IC, 140…R / W channel, 150…HDC, 24…VCM, 30…Arm, DK… Disk, L...Recording layer, S...System area, U...User data area, BA...Band, TR, STR, CTR...Track, SC...Sector, RSC...Target sector, CSC...Corrupt target sector, HD...Head, WHD...Write head, RHD...Read head, PE...Positioning error, TM...Track margin, PO...Reference radius position, WOS...Write-off track slice, d1...Radial direction, d2...Travel direction, d3...Rotation direction, d5...Overwrite direction, Da...First direction.

Claims

1. A disk having a first data track and a second data track adjacent to each other on a recording layer, wherein the first data track and the second data track each include a plurality of target sectors on which data is to be written, and the first data track is located in a first direction parallel to the radial direction of the disk with respect to the second data track, A head having a write head for writing data to the recording layer and a read head for reading data from the recording layer, A read processing unit capable of performing a seek operation to seek the read head, A write processing unit capable of performing a write operation to write data to the recording layer, An error correction unit that performs error correction on the data of one or more corrupted target sectors of the plurality of target sectors of the first data track that are determined to have corrupted data, A buffer memory capable of holding multiple data, including first user data and second user data, A management unit capable of selectively executing: a first management that prohibits overwriting the first user data in the buffer memory; a second management that permits overwriting all of the first user data in the buffer memory; and a third management that permits overwriting of data belonging to the first group and the second group of the first user data in the buffer memory, while prohibiting overwriting of data belonging to the third group of the first user data in the buffer memory. Correction limit determination unit, It comprises a determination unit, During the first write period, which is the period after the write processing unit has performed the write processing to write the first data including the first user data to the plurality of target sectors of the first data track and during the period in which the write processing unit performs the write processing to write the second data including the second user data to the plurality of target sectors of the second data track, The read processing unit performs a seek process to move the read head, and positions the write head opposite the second data track. The correction limit determination unit acquires information that the position of the light head extends beyond the reference radius position in the first direction each time data is written to the target sector of the second data track. The management unit shall perform the first management, The unit that makes the determination said, Based on the information acquired by the correction limit determination unit, if it determines that the error correction of the first user data on the first data track by the error correction unit has not exceeded the limit, the write processing unit is instructed to continue the write process on the second data track, and the management unit is instructed to perform the second management instead of the first management. Based on the aforementioned information, if the error correction unit determines that the error correction of the first user data on the first data track has exceeded its limit, the write processing unit is instructed to continue the write process on the second data track, and the management unit is instructed to perform the third management instead of the first management. During the first light period, or after the first light period, The determination unit causes the management unit to perform a process to save the data belonging to the third group to a non-volatile recording medium. The data belonging to the first group is the original data of one or more target sectors of the first data track that are determined not to be corrupted. The data belonging to the second group is the original data of one or more first corrupted target sectors of the plurality of target sectors of the first data track that are determined to have corrupted data, and is the original data of data within the range in which the error correction unit can perform the error correction. The data belonging to the third group is the original data of one or more second corrupted target sectors of the plurality of target sectors of the first data track that are determined to have corrupted data, and is the original data of data that has been missed from the range in which the error correction unit can perform the error correction. Magnetic disk drive.

2. The first user data is written to all target sectors of the first data track, or both the first user data and the first parity generated based on the first user data are written. The second user data is written to all target sectors of the second data track, or both the second user data and the second parity generated based on the second user data are written. The magnetic disk device according to claim 1.

3. The correction limit determination unit measures the actual excess amount by which the position of the light head extends beyond the reference radius position in the first direction each time the second data is written to each of the target sectors of the second data track, and updates the cumulative actual excess amount, which is the sum of the actual excess amounts. The information acquired by the correction limit determination unit is the cumulative measured excess amount, During the first light period, The unit that makes the determination said, If it is determined that the cumulative measured excess amount is less than or equal to the upper threshold, the write processing unit is instructed to continue the write processing for the second data track, and the management unit is instructed to perform the second management, the upper threshold being a value that indicates the limit of the range in which the error correction for the first data track is possible. If it is determined that the cumulative measured excess amount exceeds the upper limit threshold, the write processing unit is instructed to continue the write process for the second data track, the management unit is instructed to execute the third management, and the correction limit determination unit is instructed to subtract the measured excess amount, which is measured each time one or more second corrupted sectors are formed in the first data track, from the cumulative measured excess amount and update the cumulative measured excess amount as needed. The magnetic disk device according to claim 1.

4. The measured excess amount when one or more first corrupted sectors are formed in the first data track is defined as the first measured excess amount. If the measured excess amount when one or more second corrupted sectors are formed in the first data track is defined as the second measured excess amount, The second measured excess amount is greater than or equal to the first measured excess amount. The magnetic disk device according to claim 3.

5. The correction limit determination unit counts the number of one or more corrupted sectors in the first data track and updates the cumulative number, which is the sum of the counts. The information acquired by the correction limit determination unit further includes the cumulative number, During the first light period, The unit that makes the determination said, If it is determined that the cumulative measured excess amount is less than or equal to the upper threshold, and that the cumulative number is less than or equal to the upper limit, the write processing unit is instructed to continue the write processing for the second data track, and the management unit is instructed to execute the second management, wherein the upper limit is the number that indicates the limit of the range in which the error correction for the first data track is possible. If it is determined that the cumulative measured excess amount exceeds the upper limit threshold, the write processing unit is instructed to continue the write process for the second data track, the management unit is instructed to execute the third management, and the correction limit determination unit is instructed to subtract the measured excess amount, which is measured each time one or more second corrupted sectors are formed in the first data track, from the cumulative measured excess amount and update the cumulative measured excess amount as needed. If it is determined that the cumulative number exceeds the upper limit, the write processing unit is instructed to continue the write process on the second data track, the management unit is instructed to execute the third management, and the correction limit determination unit is instructed to update the cumulative number by subtracting the number of second corrupted sectors, which is counted each time one or more second corrupted sectors are formed on the first data track, from the cumulative number. If the cumulative number exceeds the upper limit, The total number of the one or more first damaged sectors matches the upper limit number. The magnetic disk device according to claim 3.

6. The correction limit determination unit counts the number of one or more corrupted sectors in the first data track and updates the cumulative number, which is the sum of the counts. The information acquired by the correction limit determination unit is the cumulative number, During the first light period, The unit that makes the determination said, If it is determined that the cumulative number is less than or equal to the upper limit, the write processing unit is instructed to continue the write processing for the second data track, and the management unit is instructed to perform the second management, wherein the upper limit is the number that indicates the limit of the range in which the error correction for the first data track is possible. If it is determined that the cumulative number exceeds the upper limit, the write processing unit is instructed to continue the write process on the second data track, the management unit is instructed to execute the third management, and the correction limit determination unit is instructed to update the cumulative number by subtracting the number of second corrupted sectors, which is counted each time one or more second corrupted sectors are formed on the first data track, from the cumulative number. If the cumulative number exceeds the upper limit, The total number of the one or more first damaged sectors matches the upper limit number. The magnetic disk device according to claim 1.

7. The first data track and the second data track are located in the user data area of ​​the recording layer. The non-volatile recording medium is the system area of ​​the recording layer, The magnetic disk device according to claim 1.

8. The user data area has multiple bands, each having multiple data tracks. The plurality of bands include a first band which includes the first data track and the second data track, The timing at which the management unit saves the data belonging to the third group to the system area is: After the write process of writing the second data to the plurality of target sectors of the second data track has been completed, or After the write process, which writes data to the plurality of data tracks of the first band, has been completed, The magnetic disk device according to claim 7.

9. The non-volatile recording medium is a non-volatile memory located outside the disk. The magnetic disk device according to claim 1.

10. The user data area of ​​the recording layer has multiple bands, each having multiple data tracks. The plurality of bands include a first band which includes the first data track and the second data track, The timing at which the management unit saves the data belonging to the third group to the system area of ​​the recording layer is: After the timing at which the determination unit determines that the error correction of the first user data on the first data track has exceeded the limit, After the write process of writing the second data to the plurality of target sectors of the second data track has been completed, or After the write process, which writes data to the plurality of data tracks of the first band, has been completed, The magnetic disk device according to claim 9.

11. The writing unit is a tile-type recording unit that writes the second data of the second data track to the first data of the first data track in a superimposing direction opposite to the first direction. The magnetic disk device according to claim 1.

Images