Magnetic disk device

Abstract

To provide a magnetic disk device capable of suppressing wear of a write head.SOLUTION: A magnetic disk device includes a disk, a write head, a write processing unit that selects a roof shingle recording type and causes the write head to write data to each band BA, a determination unit, and a refresh processing unit. The determination unit determines whether or not there is a quality-degraded recording sector DRSC among all recording sectors RSC in each band BA. When it is determined that a target band TBA includes the quality-degraded recording sector DRSC among the plurality of bands BA, the refresh processing unit refreshes a plurality of target recording sectors TSC. The plurality of target recording sectors TSC include the quality-degraded recording sector DRSC. In the target band TBA, the number of the plurality of target recording sectors TSC is less than a total number of recording sectors RSC.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a magnetic disk drive. [Background technology]

[0002] Known magnetic disk devices include conventional magnetic recording (CMR) type (or conventional recording type) magnetic disk devices that write multiple tracks at intervals in the radial direction of the disk, shingled magnetic recording (SMR or shingled write recording (SWR) type) magnetic disk devices that overwrite multiple tracks in the radial direction of the disk, and hybrid recording type magnetic disk devices that can select between conventional recording type and shingled recording type. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-037511 [Patent Document 2] U.S. Patent No. 11,081,135 [Patent Document 3] U.S. Patent No. 10,460,759 [Patent Document 4] U.S. Patent No. 11200911 [Patent Document 5] U.S. Patent No. 11,646,051 Summary of the Invention [Problem to be solved by the invention]

[0004] This embodiment provides a magnetic disk drive that can suppress wear on the write head. [Means for solving the problem]

[0005] A magnetic disk device according to an embodiment includes: a disk having a plurality of bands each including a plurality of tracks, each of the tracks including a plurality of sectors; a write head for writing data to the disk; a write processing unit for selecting a shingled recording format in which data is written to the plurality of tracks in an overwrite direction parallel to a radial direction of the disk and causing the write head to write data to each of the bands; a determination unit for determining whether or not there is a quality-deteriorated recording sector in all recording sectors to which data is written, the quality of recorded data being lower than a reference level; and a refresh processing unit for, when it is determined that there is a target band including the quality-deteriorated recording sector among the plurality of bands, reading target data of a plurality of target recording sectors to be refreshed among all recording sectors of the target band, rewriting the target data to the plurality of target recording sectors, and refreshing the plurality of target recording sectors, wherein the plurality of target recording sectors include the quality-deteriorated recording sector, and the number of the plurality of target recording sectors in the target band is less than the number of all recording sectors. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram showing the configuration of a magnetic disk device according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a part of the magnetic disk device, showing a plurality of disks and a plurality of heads. [Figure 3] FIG. 3 is a schematic diagram showing an example of the arrangement of a plurality of servo areas and a plurality of data areas on one disk according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing three tracks in the user data area of ​​the disk shown in FIG. 3 where shingled recording is performed, and a write head. [Figure 5] FIG. 5 is a schematic diagram showing three tracks of the media cache where normal recording processing of the disc shown in FIG. 3 is performed, and the write head. [Figure 6] FIG. 6 is a schematic diagram showing an example of a data write process on a disk. [Figure 7] FIG. 7 is a schematic diagram showing two bands and one guard band in the user data area shown in FIG. [Figure 8] FIG. 8 is a schematic diagram showing three sectors in one track of the band shown in FIG. [Figure 9] FIG. 9 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining a refresh processing method according to Example 1 of the above embodiment. [Figure 10] FIG. 10 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining a refresh processing method according to a first comparative example. [Figure 11] FIG. 11 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining the refresh processing method according to Example 2 of the above embodiment and the refresh processing method according to Example 5 of the above embodiment. [Figure 12] FIG. 12 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining a refresh processing method according to a second comparative example. [Figure 13] FIG. 13 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining a refresh processing method according to Example 3 of the above embodiment. [Figure 14] FIG. 14 is a schematic diagram showing the two bands and one guard band shown in FIG. 7, and is a diagram for explaining the refresh processing method according to Example 4 of the above embodiment and the refresh processing method according to Example 6 of the above embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] (One embodiment) A magnetic disk device 1 according to one embodiment will be described in detail below with reference to the drawings. First, the configuration of the magnetic disk device 1 will be described. FIG. 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 selects and executes a normal recording type and a shingled recording type. However, the technology described below may also be applied to a shingled recording type magnetic disk device.

[0008] 1, the magnetic disk device 1 includes a plurality of, for example, 1 to 10 disks (magnetic disks) DK as recording media, a spindle motor (SPM) 20 as a drive motor, a head stack assembly 22, a driver IC 120, a head amplifier integrated circuit (hereinafter referred to as head amplifier IC or preamplifier) ​​130, a volatile memory 70, a buffer memory (buffer) 80, a nonvolatile memory 90, and a system controller 110 which is a one-chip integrated circuit. The magnetic disk device 1 is also connected to a host system (hereinafter simply referred to as host) 100.

[0009] Each disk DK has a diameter of, for example, 97 mm (3.8 inches) and has a recording layer (magnetic recording layer) on both sides. In this embodiment, the magnetic disk device 1 includes 1 to 11 disks DK, but the number of disks DK is not limited to this.

[0010] The head stack assembly 22 is driven by a voice coil motor (hereinafter referred to as VCM) 24 to control the movement of the head HD mounted on the arm 30 to a target position on the disk DK, that is, to seek. The disk DK has a user data area U that can be used by the user and a system area S in which information required for system management is written, as areas where data can be written.

[0011] The head HD records and reproduces information on the disk DK. The head HD has a slider as its main body, and is equipped with a write head WHD and a read head RHD mounted on the slider. The write head WHD writes data to the recording layer of the disk DK. The read head RHD reads data from the data tracks on the recording layer of the disk DK.

[0012] The driver IC 120, under the control of the system controller 110 (more specifically, the MPU 60 described later), controls the driving of the SPM 20 and VCM 24. The SPM 20 supports and rotates a plurality of discs DK.

[0013] The head amplifier IC 130 includes a read amplifier and a write driver. The read amplifier amplifies a read signal read from the disk DK and outputs it to the system controller 110 (more specifically, to a read / write (R / W) channel 140, which will be described later). The write driver outputs a write current to the head HD according to the signal output from the R / W channel 140.

[0014] The volatile memory 70 is a semiconductor memory in which stored data is lost when the power supply is cut off. The volatile memory 70 stores data and the like required for processing in each part of the magnetic disk device 1. The volatile memory 70 is, for example, a DRAM (Dynamic Random Access Memory) or an SDRAM (Synchronous Dynamic Random Access Memory).

[0015] The buffer memory 80 is a semiconductor memory that temporarily records data and the like transmitted and received between the magnetic disk device 1 and the host 100. The buffer memory 80 may be configured integrally with the volatile memory 70. The buffer memory 80 is, for example, a DRAM, an SRAM (Static Random Access Memory), an SDRAM, an FeRAM (Ferroelectric Random Access Memory), an MRAM (Magnetoresistive Random Access Memory), or the like.

[0016] The buffer memory 80 includes a cache 81. The cache 81 includes a first area used as a read cache and a second area used as a write cache, and temporarily stores commands and the like received from the host 100. The first area of ​​the cache 81 temporarily stores read commands received from the host 100. The second area of ​​the cache 81 temporarily stores write data including write commands received from the host 100 and user data corresponding to the write commands.

[0017] The nonvolatile memory 90 is a semiconductor memory that records stored data even when the power supply is cut off. The nonvolatile memory 90 is, for example, a NOR or NAND type flash ROM (Flash Read Only Memory: FROM).

[0018] The system controller (controller) 110 is realized, for example, using a large-scale integrated circuit (LSI) called a system-on-a-chip (SoC), in which multiple elements are integrated on 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 of read data transferred from the disk DK to the host 100 and write data transferred from the host 100 in response to instructions from the MPU 60 (described later). The R / W channel 140 has a circuit or function for modulating 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, the HDC 150, the MPU 60, etc.

[0020] The HDC 150 controls data transfer between the host 100 and the R / W channel 140 in response to instructions from the MPU 60, which will be described later. The HDC 150 is electrically connected to, for example, the R / W channel 140, the MPU 60, the volatile memory 70, the buffer memory 80, the non-volatile memory 90, and the like.

[0021] The MPU 60 is a control unit and a main controller that controls each unit of the magnetic disk device 1. The MPU 60 controls the VCM 24 via the driver IC 120 and executes servo control to position the head HD. The MPU 60 controls the operation of writing data to the disk DK and selects a destination for write data transferred from the host 100. The MPU 60 also controls the operation of reading data from the disk DK and controls the processing of read data transferred from the disk DK to the host 100. The MPU 60 is connected to each unit of the magnetic disk device 1. The MPU 60 is electrically connected to, for example, the driver IC 120, the R / W channel 140, the HDC 150, etc.

[0022] The MPU 60 includes a read / write processing unit 61, a determination unit 62, a refresh processing unit 63, a counter 64, a command execution unit 65, a detection unit 66, etc. The MPU 60 executes the processing of each of these units, for example, the read / write processing unit 61, the determination unit 62, the refresh processing unit 63, the counter 64, the command execution unit 65, the detection unit 66, etc., on firmware. Note that the MPU 60 may include each of these units as a circuit.

[0023] The read / write processing unit 61 has a write processing unit 61a and a read processing unit 61b. In accordance with commands from the host 100, the write processing unit 61a controls the data write processing, and the read processing unit 61b controls the data read processing, causing the read head RHD to read data from the disk DK. The read / write processing unit 61 controls the VCM 24 via the driver IC 120, positions the head HD to a target position (a predetermined radial position) on the disk DK, and executes the read processing or the write processing.

[0024] FIG. 2 is a perspective view showing a part of the magnetic disk device 1, and shows a plurality of disks DK and a plurality of heads HD. As shown in Fig. 2, the direction in which the disk DK rotates in the circumferential direction is referred to as the rotation direction d3. Note that in the example shown in Fig. 2, the rotation direction is shown counterclockwise, but it may be the opposite (clockwise). Also, the moving direction d2 of the head HD relative to the disk DK is opposite to the rotation direction d3. The moving direction d2 is the direction in which the head HD sequentially writes and reads data to and from 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.

[0025] The magnetic disk device 1 includes i disks, disks DK1 to DKi, and j heads, heads HD1 to HDj. In this embodiment, the number of heads HD is twice the number of disks DK (j=2×i). The disks DK1 to DKi are arranged coaxially and stacked with a gap between them. The disks DK1 to DKi have the same diameter. Here, terms such as "same," "identical," "matched," and "equivalent" not only mean exactly the same, but also mean different enough to be considered substantially the same. The diameters of the disks DK1 to DKi may be different from each other.

[0026] Each disc DK has recording layers L on both sides. For example, disc DK1 has a first recording layer La1 and a second recording layer Lb1 opposite the first recording layer La1. Disc DK2 has a first recording layer La2 and a second recording layer Lb2 opposite the first recording layer La2. Disc DKi has a first recording layer Lai and a second recording layer Lbi opposite the first recording layer Lai. Each first recording layer La may also be referred to as a front surface or recording surface. Each second recording layer Lb may also be referred to as a back surface or recording surface.

[0027] 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.

[0028] In the user data area Ua1 (first recording layer La1), the track sandwiched between the double dashed lines in the figure is called track Ta1. In the user data area Ub1 (second recording layer Lb1), the track located on the opposite side of track Ta1 is called track Tb1. In the user data area Ua2 (first recording layer La2), the track sandwiched between the double dashed lines in the figure is called track Tc1, and in the user data area Ub2 (second recording layer Lb2), the track located on the opposite side of track Tc1 is called track Td1. In the user data area Uai (first recording layer Lai), the track sandwiched between the double dashed lines in the figure is called track Te1. In the user data area Ubi (second recording layer Lbi), the track located on the opposite side of track Te1 is called track Tf1. In this embodiment, the tracks Ta1, Tb1, Tc1, Td1, Te1, and Tf1 are located on the same cylinder.

[0029] 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 the disk DK1, writes data to the first recording layer La1, and reads data from the first recording layer La1. Head HD2 faces the second recording layer Lb1 of the disk DK1, writes data to the second recording layer Lb1, and reads data from the second recording layer Lb1.

[0030] Head HD3 faces the first recording layer La2 of disk DK2 and writes data to and reads data from the first recording layer La2. Head HD4 faces the second recording layer Lb2 of disk DK2 and writes data to and reads data from the second recording layer Lb2. Head HDj-1 faces the first recording layer Lai of disk DKi and writes data to and reads data from the first recording layer Lai. Head HDj faces the second recording layer Lbi of disk DKi and writes data to and reads data from the second recording layer Lbi.

[0031] 3 is a schematic diagram showing an example of the arrangement of a plurality of servo areas SV and a plurality of data areas DTR on one disk DK according to this embodiment. As shown in FIG. 3, in the radial direction d1 of the disk DK, the direction toward the outer periphery 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 FIG. 3, the user data area U is divided into an inner area IR located inward, an outer area OR located outward, and a middle area MR located between the inner area IR and the outer area OR.

[0032] The disk DK has a plurality of servo areas SV and a plurality of data areas DTR. The plurality of servo areas 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 plurality of servo areas 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 plurality of servo areas 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. Furthermore, the plurality of servo areas SV may, for example, be arranged in an island-like manner in the radial direction and be discretely arranged at predetermined intervals in the circumferential direction.

[0033] Hereinafter, one servo area SV in a given track may be referred to as a "servo sector." Note that a "servo area SV" may also be referred to as a "servo sector SV." A servo sector contains servo data. Hereinafter, "the arrangement of several servo data that make up a servo sector" may also be referred to as a "servo pattern." Note that "servo data written in a servo sector" may also be referred to as a "servo sector."

[0034] Each of the multiple data areas DTR is disposed between multiple servo areas SV. For example, a data area DTR corresponds to an 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." Also, a "pattern composed of several pieces of data" may also be referred to as a "data pattern." In the example shown in FIG. 3, the data pattern of a given track is composed of multiple servo data (servo sectors) and multiple user data (data sectors).

[0035] The servo area SV has a plurality of zone servo areas ZSV, etc. In addition to the zone servo areas ZSV, the servo area SV may also include an area including a gap (a deviation in the circumferential position of two zone servo areas), an area including servo data, a data area DTR, etc. The plurality of zone servo areas ZSV are discretely arranged along the radial direction. Each of the plurality of zone servo areas ZSV extends in the radial direction.

[0036] One zone servo area (servo area) ZSV in a specified track may be referred to as a "zone servo sector" or "servo sector." Note that a "zone servo area (servo area) ZSV" may also be referred to as a "zone servo sector ZSV" or "servo sector ZSV." "Servo data written in a zone servo sector" may also be referred to as a "zone servo sector" or "servo sector." Hereinafter, "the arrangement of several servo data constituting a zone servo sector" may also be referred to as a "zone servo pattern" or "servo pattern." Hereinafter, one servo area SV in a specified track may also be referred to as a "zone pattern sector."

[0037] Note that a "servo area SV" may also be referred to as a "zone pattern sector." "At least one piece of data, etc. written to a zone pattern sector" may also be referred to as a "zone pattern sector." A zone pattern sector includes at least one zone servo sector. Hereinafter, "data pattern of a zone pattern sector" may also be referred to as a "zone data pattern."

[0038] 3, the servo area SV has zone servo areas ZSV0, ZSV1, and ZSV2. The zone servo areas ZSV0, ZSV1, and ZSV2 are arranged in a staggered pattern in the radial direction. The zone servo areas ZSV0, ZSV1, and ZSV2 may also be arranged in a stepped pattern in the radial direction.

[0039] Zone servo area ZSV2 is located closer to the inner periphery than zone servo area ZSV1. Zone servo area ZSV0 is located closer to the outer periphery than zone servo area ZSV1. For example, zone servo area ZSV2 is arranged from inner area IR to middle area MR, zone servo area ZSV1 is arranged from inner area IR to outer area OR, and zone servo area ZSV0 is arranged from middle area MR to outer area OR. Hereinafter, in a given servo area SV, a given radial area in which multiple zone servo areas ZSV are arranged in the circumferential direction may also be referred to as a zone servo boundary area, a double servo area, or a double zone servo area ZB.

[0040] In the example shown in Fig. 3, the primary servo areas SVO and the secondary servo areas SVE are alternately arranged at intervals in the circumferential direction. For example, one secondary servo area SVE is arranged between two primary servo areas SVO that are consecutively arranged at an interval in the circumferential direction. In other words, one secondary servo area SVE is arranged between two primary servo areas SVO that are consecutively arranged at an interval in the circumferential direction. For example, if consecutive numbers are assigned to all the servo areas SV of the disk DK in order, the primary servo areas SVO correspond to the odd-numbered servo areas SV, and the secondary servo areas SVE correspond to the even-numbered servo areas SV. Note that two or more secondary servo areas SVE may be arranged between two primary servo areas SVO that are consecutively arranged at an interval in the circumferential direction.

[0041] The primary servo area SVO and the secondary servo area SVE may be, for example, composed only of a servo area (hereinafter sometimes referred to as a normal servo area) that reads and demodulates servo data as a whole. Hereinafter, "reading and demodulating servo data" may also be referred to as "servo reading." The primary servo area SVO and the secondary servo area SVE may be, for example, composed of a normal servo area and a servo area (hereinafter sometimes referred to as a short servo area) that servo reads a circumferential range of servo data that is smaller than the circumferential range of servo data servo read in the normal servo area.

[0042] The media cache M is allocated to the disk DK. However, the media cache M does not have to be located on the disk DK. By using the above-mentioned plurality of servo data, for example, it is possible to position the head HD so as to obtain a predetermined amount of off-track.

[0043] In the description of this embodiment, the disk DK has three zones, but the number of zones on the disk DK can be changed in various ways. The number of zones on the disk DK may be 30 to 40. Furthermore, each zone has multiple bands. For example, each zone may have several hundred bands.

[0044] 4 is a schematic diagram showing the write head WHD and three tracks STR in the user data area U where shingled recording is performed on the disk DK shown in FIG. 3. The user data area U is a shingled recording area. Within the user data area U, it is permitted to write data sequentially in band units, that is, shingled recording is permitted.

[0045] As shown in Fig. 4, the write head WHD can sequentially write data to the disk DK in the travel direction d2. The read head RHD shown in Fig. 3 can also sequentially read data written to the disk DK in the travel direction d2.

[0046] The direction in which a plurality of tracks STR are continuously shingled-recorded in a direction parallel to the radial direction d1, that is, the direction in which the next track STR to be written is overlapped on the previously written track STR in the radial direction d1, is referred to as the overwrite direction or recording progress direction. In the band BAe shown in Figure 4, the overwrite direction d5 is an inward direction, but the overwrite direction may also be an outward direction. For example, the overwrite direction applied to multiple bands BA (multiple zones Z) located on the outer side of a specific radial position may be opposite to the overwrite direction applied to multiple bands BA (multiple zones Z) located on the inner side of the specific radial position.

[0047] Band BAe has a plurality of tracks STR, including tracks STRe, STRe+1, and STRe+2. Tracks STRe, STRe+1, and STRe+2 are continuously overwritten in the order shown in the overwrite direction d5. Of tracks STRe, STRe+1, and STRe+2, track STRe corresponds to the track onto which data is written first, and track STRe+2 corresponds to the track onto which data is written last.

[0048] Track STRe has a track center STCe at the center in the radial direction d1 when no other tracks have been overwritten. Track STRe+1 has a track center STCe+1 at the center in the radial direction d1 when no other tracks have been overwritten. Track STRe+2 has a track center STCe+2 at the center in the radial direction d1 when no other tracks have been overwritten.

[0049] In the example shown in Figure 4, tracks STRe, STRe+1, and STRe+2 are written at a pitch (shingled recording track pitch) STP. The track center STCe of track STRe and the track center STCe+1 of track STRe+1 are spaced apart in the radial direction d1 by a pitch STP. The track center STCe+1 of track STRe+1 and the track center STCe+2 of track STRe+2 are spaced apart in the radial direction d1 by a pitch STP. Tracks STRe to STRe+2 may be written at different pitches.

[0050] The width in the radial direction d1 of the area of ​​track STRe where track STRe+1 is not overwritten is the same as the width in the radial direction d1 of the area of ​​track STRe+1 where track STRe+2 is not overwritten. Note that the width in the radial direction d1 of the area of ​​track STRe where track STRe+1 is not overwritten may be different from the width in the radial direction d1 of the area of ​​track STRe+1 where track STRe+2 is not overwritten.

[0051] In Fig. 4, for convenience of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumferential direction. Also, each track STR may be wavy, extending in the circumferential direction while fluctuating in the radial direction d1. Note that in Fig. 4, three tracks STR are overwritten, but two tracks STR may be overwritten, or more than three tracks STR may be overwritten.

[0052] The write processing unit 61a selects a shingled recording format in which data is written to multiple tracks STR in an overwrite direction d5, and causes the write head WHD to write data to each band BA. In the example shown in Fig. 4, the write processing unit 61a performs shingled recording on tracks STRe to STRe+2 in band BAe sequentially inward (in the overwrite direction d5) at a pitch STP. Since data is written to the user data area U using the shingled recording format, the recording density of the user data area U can be improved.

[0053] The write processing unit 61a writes track STRe+1 inward from track STRe at pitch STP, and overwrites track STRe+1 on a part of the inner periphery of track STRe. The write processing unit 61a writes track STRe+2 inward from track STRe+1 at pitch STP, and overwrites track STRe+2 on a part of the inner periphery of track STRe+1.

[0054] Figure 5 is a schematic diagram showing the three tracks CTR and the write head WHD of the media cache M where normal recording processing of the disk DK shown in Figure 3 is performed. 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 the system area S, that is, normal recording is permitted.

[0055] 5, the media cache M has a plurality of tracks CTR including tracks CTRe, CTRe+1, and CTRe+2. For example, the widths (track widths) of the tracks CTRe, CTRe+1, and CTRe+2 in the radial direction d1 are the same. Note that the track widths of the tracks CTRe to CTRe+2 may be different from each other.

[0056] Track CTRe has a track center CTCe at the center in the radial direction d1, track CTRe+1 has a track center CTCe+1 at the center in the radial direction d1, and track CTRe+2 has a track center CTCe+2 at the center in the radial direction d1. In the example shown in Fig. 5, tracks CTRe, CTRe+1, and CTRe+2 are written at a 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 the pitch CTP. The track center CTCe+1 of track CTRe+1 and the track center CTCe+2 of track CTRe+2 are separated by the pitch CTP.

[0057] The tracks CTRe and CTRe+1 are separated by a gap GP. The tracks CTRe+1 and CTRe+2 are separated by a gap GP. The tracks CTRe to CTRe+2 may be written at different pitches. For ease of explanation, each track CTR is shown as a rectangle in FIG. 5, but in reality, each track CTR is curved along the circumferential direction. Furthermore, each track CTR may be wavy, extending in the circumferential direction while fluctuating in the radial direction d1.

[0058] The write processing unit 61a can select a normal recording format in which data is written to a plurality of tracks CTR at intervals in the radial direction d1 of the disk DK and perform the write processing. In the example shown in Fig. 4, the write processing unit 61a positions the write head WHD at the track center CTCe in a predetermined area of ​​the disk DK and performs normal recording on the track CTRe or a predetermined sector of the track CTRe.

[0059] The write processing unit 61a positions the write head WHD at a track center CTCe+1 that is spaced inward from the track center CTCe of the track CTRe by the pitch CTP, and performs normal recording on the track CTRe+1 or a predetermined sector of the track CTRe+1. The write processing unit 61a positions the write head WHD at a track center CTCe+2 that is spaced inward from the track center CTCe+1 of the track CTRe+1 by the pitch CTP, and performs normal recording on the track CTRe+2 or a predetermined sector of the track CTRe+2.

[0060] The write processing unit 61a may normally record tracks CTRe, CTRe+1, and CTRe+2 sequentially in a predetermined area of ​​the disk DK, or may normally record randomly in a predetermined sector of track CTRe, a predetermined sector of track CTRe+1, and a predetermined sector of track CTRe+2.

[0061] 6 is a schematic diagram showing an example of a data write process on a disk DK. As shown in FIG. 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 overwrite direction in the order in which they are written.

[0062] Bands BAa and BAb are adjacent to each other in the radial direction d1, and bands BAb and BAc are adjacent to each other in the radial direction d1. Band BAa includes x tracks: STRa0, STRa1, STRa2, ..., STRa(x-3), STRa(x-2), and STRa(x-1). Tracks STRa0 to STRa(x-1) are shingled recorded in the order listed in the overwrite direction d5. In band BAa, track STRa0 corresponds to the first track onto which data is written first, and track STRa(x-1) corresponds to the last track onto which data is written last.

[0063] Band BAb includes x tracks: STRb0, STRb1, STRb2, ..., STRb(x-3), STRb(x-2), and STRb(x-1). Tracks STRb0 to STRb(x-1) are shingled recorded in the order listed in the overwrite direction d5. In band BAb, track STRb0 corresponds to the first track onto which data is written first, and track STRb(x-1) corresponds to the last track onto which data is written last.

[0064] Band BAc includes tracks STRc0, STRc1, STRc2, ..., STRc(x-3), STRc(x-2), and STRc(x-1). Tracks STRc0 to STRc(x-1) are shingled recorded in the order listed in the overwrite direction d5. In band BAc, track STRc0 corresponds to the first track onto which data is written first, and track STRc(x-1) corresponds to the last track onto which data is written last.

[0065] Each band BA belonging to the same zone Z has the same number of tracks STR. For example, each band BA belonging to zone Ze has the same number of tracks STR. In other words, the number of tracks STR that a band BA has is fixed for each zone Z. In this example, the number of tracks STR that each band BA belonging to zone Ze has is x.

[0066] Fig. 6 shows tracks CTR(x-2) and CTR(x-1). In Fig. 6, tracks CTR(x-2) and CTR(x-1) are usually recorded in the media cache M or the system area S. Tracks CTR(x-2) and CTR(x-1) are adjacent to each other in the radial direction d1.

[0067] Fig. 7 is a schematic diagram showing two bands BAa and BAb and one guard band GB in the user data area U shown in Fig. 6. As shown in Fig. 7, the shingled recording method differs from the normal recording method in that part of the track STR is overwritten, and therefore the MPU 60 manages the track group in the user data area U in units called bands.

[0068] A guard band GB is generally provided between bands BA adjacent to each other 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 has the role of suppressing interference between adjacent bands BA. The guard band GB makes it possible to perform shingled recording in units of one band BA. Furthermore, the guard band GB makes it possible to separate the ranges (bands BA) to be written sequentially.

[0069] For example, the track center STCa(x-3) of track STRa(x-3), the track center STCa(x-2) of track STRa(x-2), the track center STCa(x-1) of track STRa(x-1), the track center GTC of the guard track GTR, the track center STCb0 of track STRb0, the track center STCb1 of track STRb1, and the track center STCb2 of track STRb2 are positioned at equal pitches in the overwrite direction d5.

[0070] Excluding 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 required specifications. The MPU 60 can record the same amount of data in each band BA. Typically, the recording capacity of each band BA is 128 MiB or 256 MiB.

[0071] 8 is a schematic diagram showing three sectors SCe, SC(e+1), and SC(e+2) of one track STRa0 of band BAa shown in FIG. 6. As shown in FIG. 8, each track STR has a plurality of sectors SC. Track STRa1 has a plurality of sectors SC including sectors SCe, SC(e+1), and SC(e+2). 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. Each sector SC has a length Ls in the circumferential direction of the disk DK. The write head WHD is a magnetic head for energy-assisted recording (EAMR), which uses energy-assisted magnetic recording. Energy-assisted recording methods include microwave-assisted magnetic recording (MAMR) and heat-assisted magnetic recording (HAMR).

[0072] In the MAMR method, an element that generates microwaves (high-frequency magnetic fields) by applying an electric current is placed at the tip of the write head WHD. When the medium is exposed to the high-frequency magnetic field from the write head WHD that performs MAMR recording, spin resonance occurs, causing the medium to reverse with a magnetic field weaker than the required reversal field. This allows data to be recorded with pinpoint accuracy using a smaller write head WHD, thereby improving the recording density of the disk DK.

[0073] The product life of the write head WHD that performs MAMR recording becomes shorter as the amount of power applied to the write head WHD increases. In other words, the product life of the write head WHD becomes shorter as the amount of data written to the disk DK increases. Therefore, from the perspective of product life, it is desirable for the write head WHD to reduce the amount of data written to the disk DK.

[0074] In this embodiment, the write head WHD is configured to utilize energy other than magnetic energy, but this is not limited to this, and the write head WHD may also be a magnetic head that is not configured to perform energy-assisted recording.

[0075] (Example 1 of an embodiment) Next, a refresh processing method according to Example 1 of the above embodiment will be described. Fig. 9 is a schematic diagram showing two bands BAa and BAb and one guard band GB shown in Fig. 7, and is a diagram for explaining the refresh processing method according to Example 1.

[0076] 9, for convenience of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumferential direction. Also, although multiple tracks STR are arranged in the overwrite direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overwrite direction d5 while overlapping each other. In the figure, the recording sectors RSC are marked with a dot pattern. The unused sectors VSC are shown as a solid color. Among the recording sectors RSC, the quality-degraded recording sectors DRSC are marked with a diagonal grid pattern instead of a dot pattern. Among the recording sectors RSC, the target recording sectors TSC are marked with diagonal lines instead of a dot pattern. The quality-degraded recording sectors DRSC are also the target recording sectors TSC.

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

[0078] In this embodiment, band BAb is the band to be subjected to the refresh process, and is referred to as target band TBA. On the other hand, band BAa is the band adjacent to band BAb, and is located to the right of band BAb in the overwrite direction d5, and is referred to as adjacent band ABA.

[0079] Of the multiple tracks STR in band BAa, the end track STRa(x-1) located closest to band BAb functions as the first track and includes one or more recording sectors RSC in which valid data is written. Also, track STRa(x-1) may not include unused sectors VSC in which valid data is not written, but as in this embodiment, track STRa(x-1) includes unused sectors VSC.

[0080] Of the tracks STRb in band BAb, track STRb0, which is the end track closest to band BAa, functions as the second track and is the first track in band BAb to which data is written using shingled recording.Track STRb(x-1) is the last track in band BAb to which data is written using shingled recording and functions as the third track.

[0081] In each band BA of zone Ze, all sectors SC in x-1 tracks STR numbered 0 to x-2 are sectors in which valid data is written and are recording sectors RSC. In the x-1 track STR of each band BA of zone Ze, five sectors SC numbered 0 to 4 are sectors in which valid data is written and are recording sectors RSC. On the other hand, in the x-1 track STR, the remaining sectors SC numbered 5 to y-1 are sectors in which valid data is not written and are unused sectors VSC.

[0082] However, when data is rewritten to track 1 of the shingled user data area U and track 1 is refreshed, track 2, which has been overwritten on track 1, is severely affected by writing smear. As a result, it is ultimately necessary to rewrite data to all tracks in the same band BA, including track 2, which has been overwritten. Therefore, compared to the normal recording type, the shingled recording type requires more time for writing data during the refresh process and writes more data, which tends to cause more wear on the write head WHD.

[0083] Before describing the refresh processing method according to the first embodiment, a refresh processing method according to a first comparative example will be described. As shown in Figure 10, the recording quality of data in band BAb deteriorates when adversely affected by external disturbances when writing data to disk DK, sudden deterioration in the positioning of write head WHD due to defects or changes in the flying height of write head WHD, or leakage magnetic fields from write head WHD when writing data to band BAa.

[0084] The adverse effect of the leakage magnetic field from the write head WHD on band BAb (the effect of adjacent track interference (ATI)) when writing data to band BAa is greatest when writing data to track STRa(x-1) of band BAa. In this example, when writing data to sectors SC(a,x-1,0), SC(a,x-1,1), SC(a,x-1,2), SC(a,x-1,3), and SC(a,x-1,4) of track STRa(x-1) of band BAa, sectors SC(b,0,0), SC(b,0,1), SC(b,0,2), SC(b,0,3), and SC(b,0,4) of track STRb0 of band BAb are most adversely affected by the leakage magnetic field. Sectors SC(b,0,0) to SC(b,0,4) of track STRb0 can each become a quality-degraded recording sector DRSC.

[0085] Therefore, it becomes necessary to perform a refresh process on band BAb. When performing a refresh process on band BAb, all recording sectors RSC of band BAb become target recording sectors TSC that are targets of refresh. The refresh processing unit 63 can read target data of a plurality of target recording sectors TSC (all recording sectors RSC), rewrite the target data to the plurality of target recording sectors TSC, and refresh the plurality of target recording sectors TSC. However, in the example of FIG. 10, as described above, the amount of data rewritten during refresh of band BAb cannot be reduced, which results in severe wear on the write head WHD.

[0086] Next, a refresh processing method according to the first embodiment will be described. 9, when performing the refresh process on band BAb, none of the recording sectors RSC of band BAb are set as target recording sectors TSC. The target recording sectors TSC of band BAb are a plurality of recording sectors RSC aligned in the overwrite direction d5, namely, recording sectors RSC(a,x-1,0) to RSC(a,x-1,4) of track STRa(x-1) of band BAa.

[0087] In band BAb, in the overwrite direction d5, multiple recording sectors RSC aligned in recording sectors RSC(a, x-1, 5) to RSC(a, x-1, y-1) of track STRa(x-1) are excluded from the target recording sectors TSC, which reduces the amount of data rewritten when refreshing band BAb and suppresses wear on the write head WHD.

[0088] Next, the refresh processing method according to the first embodiment will be described in detail. As shown in Figures 1 and 9, the judgment unit 62 judges whether, in each band BA, among all recording sectors RSC in which data is written, there is a quality-degraded recording sector DRSC in which the quality of the recorded data is lower than a reference level.

[0089] If the judgment unit 62 judges that there is a target band TBA containing a quality-deteriorated recording sector DRSC among the multiple bands BA, the refresh processing unit 63 reads the target data of the multiple target recording sectors TSC that are the targets of refresh among all the recording sectors RSC of the target band TBA (band BAb), rewrites the target data to the multiple target recording sectors TSC, and refreshes the multiple target recording sectors TSC.

[0090] The plurality of target recording sectors TSC includes quality-deteriorated recording sectors DRSC. In this example, the quality-deteriorated recording sectors DRSC are five recording sectors RSC, namely, recording sectors RSC(b,0,0) to RSC(b,0,4) of track STRb0. In target band TBA (band BAb), the number of the plurality of target recording sectors TSC is less than the number of all recording sectors RSC. Since the number of the plurality of target recording sectors TSC does not match the number of all recording sectors RSC, it is possible to reduce the amount of data rewritten when refreshing band BAb, and to suppress wear on the write head WHD.

[0091] Furthermore, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC aligned in the overwrite direction d5. In the overwrite direction d5, the recording sectors RSC aligned with the quality-deteriorated recording sector DRSC are set as target recording sectors TSC, but the recording sectors RSC not aligned with the quality-deteriorated recording sector DRSC are not set as target recording sectors TSC. The target recording sectors TSC can be limited (narrowed down) from all the recording sectors RSC in the target band TBA. This further reduces the amount of data rewritten when refreshing band BAb, thereby suppressing wear on the write head WHD.

[0092] Furthermore, in the target band TBA (band BAb), the plurality of target recording sectors TSC are a plurality of recording sectors RSC aligned in one or more recording sectors RSC of the track STRa(x-1) in the overwrite direction d5. In this example, in the target band TBA (band BAb), the plurality of target recording sectors TSC are a plurality of recording sectors RSC aligned in the recording sectors RSC(a,x-1,0) to RSC(a,x-1,4) of the track STRa(x-1) in the overwrite direction d5. Therefore, the target band TBA (band BAb) can be refreshed taking into consideration the adverse effect of ATI from the last track STRa(x-1) of the adjacent band ABA (band BAa).

[0093] Furthermore, the refresh processing method of the first embodiment can refresh the target band TBA (band BAb) taking into consideration the number of writes to the adjacent band ABA (band BAa). At this time, the counter 64, the nonvolatile memory 90, etc. are used. The counter 64 can count the number of writes as k each time data is written to adjacent band ABA (band BAa). For example, k=1. However, the value of k may be less than 1 or may exceed 1. The nonvolatile memory 90 functions as a recording unit and can store the cumulative number of writes. Note that the recording unit is not limited to the nonvolatile memory 90, and may be a third memory (not shown) as long as it is configured to be able to store the cumulative number of writes.

[0094] When the judgment unit 62 judges that the cumulative total number of writes to adjacent band ABA (band BAa) is less than the write count threshold, it can judge that one or more recording sectors RSC aligned with one or more recording sectors RSC of track STRa(x-1) in the radial direction d1 in track STRb0 do not correspond to quality-deteriorated recording sectors DRSC. Here, the judgment unit 62 can judge that a plurality of recording sectors RSC(b,0,0) to RSC(b,0,4) of track STRb0 aligned with a plurality of recording sectors RSC(a,x-1,0) to RSC(a,x-1,4) of track STRa(x-1) in the radial direction d1 do not correspond to quality-deteriorated recording sectors DRSC. An example of the write count threshold is 200. The write count threshold can be changed in various ways.

[0095] On the other hand, when the judgment unit 62 judges that the cumulative total number of writes to adjacent band ABA (band BAa) is equal to or greater than the write count threshold, it can judge that one or more recording sectors RSC aligned with one or more recording sectors RSC of track STRa(x-1) in the radial direction d1 of track STRb0 correspond to quality-deteriorated recording sectors DRSC. Here, the judgment unit 62 can judge that a plurality of recording sectors RSC(b,0,0) to RSC(b,0,4) of track STRb0 aligned with a plurality of recording sectors RSC(a,x-1,0) to RSC(a,x-1,4) of track STRa(x-1) in the radial direction d1 correspond to quality-deteriorated recording sectors DRSC.

[0096] In this case, when the refresh processing unit 63 refreshes a plurality of target recording sectors TSC, it can reset the cumulative total of the number of writes in the nonvolatile memory (recording unit) 90. This allows the target band TBA (band BAb) to be continuously refreshed.

[0097] (Example 2 of an embodiment) Next, a refresh processing method according to Example 2 of the above embodiment will be described. Fig. 11 is a schematic diagram showing two bands BAa and BAb and one guard band GB shown in Fig. 7, and is a diagram for explaining the refresh processing method according to Example 2.

[0098] 11, for convenience of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumferential direction. Also, although multiple tracks STR are arranged in the overwrite direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overwrite direction d5 while overlapping each other. In the figure, the recording sectors RSC are marked with a dot pattern. The unused sectors VSC are shown as a solid color. Among the recording sectors RSC, the quality-degraded recording sectors DRSC are marked with a diagonal grid pattern instead of a dot pattern. Among the recording sectors RSC, the target recording sectors TSC are marked with diagonal lines instead of a dot pattern. The quality-degraded recording sectors DRSC are also the target recording sectors TSC.

[0099] Before describing the refresh processing method according to the second embodiment, a refresh processing method according to a second comparative example will be described. As shown in Figure 12, the recording quality of data in band BAb deteriorates when adversely affected by disturbances when writing data to the disk DK, sudden deterioration in the positioning of the write head WHD due to defects, or changes in the flying height of the write head WHD. Recording sectors RSC(b,5,1) and RSC(b,3,6) of band BAb are quality-degraded recording sectors DRSC.

[0100] Therefore, it becomes necessary to perform a refresh process on band BAb. When performing a refresh process on band BAb, all recording sectors RSC of band BAb become target recording sectors TSC that are targets of refresh. The refresh processing unit 63 can read target data of a plurality of target recording sectors TSC (all recording sectors RSC), rewrite the target data to the plurality of target recording sectors TSC, and refresh the plurality of target recording sectors TSC. However, in the example of FIG. 12, as described above, the amount of data rewritten during refresh of band BAb cannot be reduced, which results in severe wear on the write head WHD.

[0101] Next, a refresh processing method according to the second embodiment will be described. 11, when performing refresh processing on band BAb, none of the recording sectors RSC of band BAb are set as target recording sectors TSC. The target recording sectors TSC of band BAb are a plurality of recording sectors RSC aligned with the quality-deteriorating recording sector DRSC(b,5,1) and a plurality of recording sectors RSC aligned with the quality-deteriorating recording sector DRSC(b,3,6) in the overwrite direction d5.

[0102] Of all the recording sectors RSC of band BAb, all recording sectors RSC numbered 0, 2 to 5, and 7 to y-1 are excluded from the target recording sectors TSC, which reduces the amount of data rewritten when refreshing band BAb and suppresses wear on the write head WHD.

[0103] Next, a refresh processing method according to the second embodiment will be described in detail. As shown in FIGS. 1 and 11, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC aligned in the overwrite direction d5. The multiple recording sectors RSC, including the quality-deteriorating recording sector DRSC(b,5,1), from recording sector RSC(b,0,1) to recording sector RSC(b,x-1,1), which are aligned in the overwrite direction d5, are each the target recording sectors TSC. Also, the multiple recording sectors RSC, including the quality-deteriorating recording sector DRSC(b,3,6), from recording sector RSC(b,0,6) to recording sector RSC(b,x-2,6), which are aligned in the overwrite direction d5, are each the target recording sectors TSC. Only the multiple recording sectors RSC, including the quality-deteriorating recording sector DRSC, which are aligned in the overwrite direction d5, can be refreshed. This reduces the amount of data rewritten when refreshing band BAb, thereby suppressing wear on the write head WHD.

[0104] Furthermore, the refresh processing method of the second embodiment can refresh the target band TBA (band BAb) during an idle period, using the cache 81, the command execution unit 65, and the like. The command execution unit 65 can execute write commands and read commands recorded in the cache 81. When the determination unit 62 determines that the cache 81 is in an idle period in which there are no unexecuted commands, the refresh processing unit 63 can refresh a plurality of target recording sectors TSC during the idle period. This can improve the processing efficiency of the MPU 60 and can also improve the utilization efficiency of the head HD, including the write head WHD.

[0105] Furthermore, the refresh processing method of the second embodiment can refresh the target band TBA (band BAb) taking into consideration the bit error rate (BER). In the second embodiment, the quality of the data recorded in the recording sector RSC of band BA is the bit error rate of the data.

[0106] The bit error rate of data recorded in the quality-degraded recording sector DRSC, which is also the bit error rate of data having a quality lower than the reference level, is higher than the reference value. On the other hand, the bit error rate of data having a quality equal to or higher than the reference level is equal to or lower than the reference value. The judgment unit 62 can judge whether there is a quality-degraded recording sector DRSC in which the bit error rate of recorded data is higher than the reference value among all recording sectors RSC in which data is written in each band BA.

[0107] In the second embodiment, the determination unit 62 detects that the bit error rate of the data of the recording sector RSC(b,5,1) is higher than the reference value and that the bit error rate of the data of the recording sector RSC(b,3,6) is also higher than the reference value, and can determine that the recording sectors RSC(b,5,1) and RSC(b,3,6) are quality-degraded recording sectors DRSC. In this way, the bit error rate of the data of the recording sector RSC can be used as an index to determine whether the recording sector corresponds to the quality-degraded recording sector DRSC.

[0108] Example 3 of an embodiment Next, a refresh processing method according to Example 3 of the above embodiment will be described. Fig. 13 is a schematic diagram showing two bands BAa and BAb and one guard band GB shown in Fig. 7, and is a diagram for explaining the refresh processing method according to Example 3.

[0109] 13, for convenience of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumferential direction. Also, although multiple tracks STR are arranged in the overwrite direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overwrite direction d5 while overlapping each other. In the figure, the recording sectors RSC are marked with a dot pattern. The unused sectors VSC are shown as a solid color. Among the recording sectors RSC, the quality-degraded recording sectors DRSC are marked with a diagonal grid pattern instead of a dot pattern. Among the recording sectors RSC, the target recording sectors TSC are marked with diagonal lines instead of a dot pattern. The quality-degraded recording sectors DRSC are also the target recording sectors TSC.

[0110] 13, among the multiple tracks STRb in the target band TBA (band BAb), track STRb3, which is different from track STRb0 and includes a quality-degraded recording sector DRSC(b,3,6), functions as the fourth track. Track STRb5, which is also different from track STRb0 and includes a quality-degraded recording sector DRSC(b,5,1), functions as the fourth track. If there are multiple tracks STRb including quality-degraded recording sectors DRSC in the target band TBA (band BAb), in this embodiment 3, track STRb3, which is located furthest up in the overwrite direction d5, of tracks STRb3 and STRb5, can be regarded as the fourth track.

[0111] In the target band TBA (band BAb), the target recording sectors TSC are all recording sectors RSC of the tracks STRb from track STRb3 to track STRb(x-1) in the overwrite direction d5. In the overwrite direction d5, the refresh process is performed on track STRb3 to which the quality-deteriorating recording sector DRSC(b,3,6) belongs, and on the tracks STRb4 to STRb(x-1) in band BAb located downstream of track STRb3.

[0112] Of all the recording sectors RSC of band BAb, all the recording sectors RSC of tracks STRb 0 to 2 are excluded from the target recording sectors TSC, which reduces the amount of data rewritten when refreshing band BAb and suppresses wear on the write head WHD.

[0113] Furthermore, when refreshing band BAb, data rewriting can start from track STRb3. Since it is no longer necessary to rewrite data to tracks STRb0 to STRb2, the time required for the refresh process can be shortened.

[0114] Example 4 of an embodiment Next, a refresh processing method according to Example 4 of the above embodiment will be described. Fig. 14 is a schematic diagram showing two bands BAa and BAb and one guard band GB shown in Fig. 7, and is a diagram for explaining a refresh processing method according to Example 4.

[0115] 14, for convenience of explanation, each track STR is shown as a rectangle, but in reality, each track STR is curved along the circumferential direction. Also, although multiple tracks STR are arranged in the overwrite direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overwrite direction d5 while overlapping each other. In the figure, the recording sectors RSC are marked with a dot pattern. The unused sectors VSC are shown as a solid color. Among the recording sectors RSC, the quality-degraded recording sectors DRSC are marked with a diagonal grid pattern instead of a dot pattern. Among the recording sectors RSC, the target recording sectors TSC are marked with diagonal lines instead of a dot pattern. The quality-degraded recording sectors DRSC are also the target recording sectors TSC.

[0116] 14, in the target band TBA (band BAb), the target recording sectors TSC are a plurality of recording sectors RSC aligned in the overwrite direction d5 from the quality-deteriorating recording sector DRSC(b,5,1) of track STRb5 to the recording sector RSC(b,x-1,1) of track STRb(x-1). Furthermore, the target recording sectors TSC are a plurality of recording sectors RSC aligned in the overwrite direction d5 from the quality-deteriorating recording sector DRSC(b,3,6) of track STRb3 to the recording sector RSC(b,x-2,6) of track STRb(x-2).

[0117] Since data only needs to be rewritten in a plurality of target recording sectors TSC including the quality-deteriorated recording sector DRSC in band BAb during refresh, wear on the write head WHD can be suppressed. Furthermore, since there is no need to rewrite data to tracks STRb0 to STRb2 when refreshing band BAb, the time required for the refresh process can be reduced.

[0118] Furthermore, in the fourth embodiment, the target band TBA (band BAb) can be refreshed during an idle period, similar to the second embodiment described above. Additionally, in the fourth embodiment, the target band TBA (band BAb) can be refreshed in consideration of the bit error rate, as in the second embodiment.

[0119] Example 5 of an embodiment Next, a refresh processing method according to Example 5 of the above embodiment will be described. The refresh processing method is the same as the refresh processing method of Example 2 above, except for the technique described in Example 5. As shown in FIGS. 1 and 11, in this fifth embodiment as well, it is possible to limit (narrow) the target recording sectors TSC from among all the recording sectors RSC of the target band TBA.

[0120] The refresh processing method of the fifth embodiment can refresh the target band TBA (band BAb) by taking into consideration the number of read retries instead of the bit error rate. The detection unit 66 can detect the number of times the same data on the disk DK is read by the read processing unit 61b.

[0121] The number of times data recorded in a quality-degraded recording sector DRSC is read, which is also the number of times data with quality lower than the reference level is read, is greater than the reference number. On the other hand, the number of times data with quality equal to or higher than the reference level is read is less than the reference number. The judgment unit 62 can judge whether there is a quality-degraded recording sector DRSC in which the number of times recorded data is read is greater than the reference number among all recording sectors RSC in which data is written, in each band BA.

[0122] In this embodiment 5, the judgment unit 62 detects that the number of times of reading data from the recording sector RSC(b,5,1) is greater than the above-mentioned reference number, and that the number of times of reading data from the recording sector RSC(b,3,6) is greater than the above-mentioned reference number, and can judge that the recording sectors RSC(b,5,1) and RSC(b,3,6) are quality-degraded recording sectors DRSC.In this way, it is possible to use the number of read retries of data from the recording sector RSC as an index to judge whether the recording sector corresponds to a quality-degraded recording sector DRSC. The fifth embodiment can achieve the same effects as the second embodiment.

[0123] Example 6 of an embodiment Next, a refresh processing method according to Example 6 of the above embodiment will be described. The refresh processing method is the same as the refresh processing method of Example 4 above, except for the technique described in Example 6. As shown in FIGS. 1 and 14, in the sixth embodiment as well, it is possible to limit (narrow) the target recording sectors TSC from among all the recording sectors RSC of the target band TBA.

[0124] The refresh processing method of the sixth embodiment can refresh the target band TBA (band BAb) by taking into consideration the number of read retries instead of the bit error rate. In this way, the number of read retries of the data of the recording sector RSC can be used as an index to determine whether the recording sector RSC corresponds to a quality-degraded recording sector DRSC. The sixth embodiment can achieve the same effects as the fourth embodiment.

[0125] According to the magnetic disk device 1 and refresh processing method according to one embodiment configured as described above, the magnetic disk device 1 includes a disk DK, a write head WHD, a write processing unit 61a, a determination unit 62, and a refresh processing unit 63. The write processing unit 61a selects a shingled recording format and causes the write head WHD to write data to each band BA. The determination unit 62 determines whether there are quality-degraded recording sectors DRSC among all recording sectors RSC in each band BA. If it is determined that there is a target band TBA containing quality-degraded recording sectors DRSC among multiple bands BA, the refresh processing unit 63 reads target data in multiple target recording sectors TSC among all recording sectors RSC in the target band TBA, rewrites the target data to the multiple target recording sectors TSC, and refreshes the multiple target recording sectors TSC. The multiple target recording sectors TSC contain quality-degraded recording sectors DRSC. In the target band TBA, the number of target recording sectors TSC is less than the total number of recording sectors RSC.

[0126] Since the amount of data rewritten during refresh of band BAb can be reduced, wear on the write head WHD can be suppressed. From the above, a magnetic disk drive 1 that can suppress wear on the write head WHD can be obtained.

[0127] Although the embodiments of the present invention have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above novel embodiments can be embodied 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 modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. For example, the above-described technique is not limited to hybrid recording type magnetic disk drives, and may be applied to shingled recording type magnetic disk drives. [Explanation of symbols]

[0128] 1...magnetic disk device, 60...MPU, 61...read / write processing unit, 61a...write processing unit, 61b...read processing unit, 62...determination unit, 63...refresh processing unit, 64...counter, 65...command execution unit, 66...detection unit, 70...volatile memory, 80...buffer memory, 81...cache, 90...nonvolatile memory, 100...host, 110...system controller, 120...driver IC, 130...head amplifier IC, 140...R / W channel 150...HDC, DK...disk, L...recording layer, Z...zone, BA...band, TBA...target band, ABA...adjacent band, STR...track, SC...sector, RSC...recording sector, TSC...target recording sector, DRSC...degraded quality recording sector, VSC...unused sector, GB...guard band, GTR...guard track, WHD...write head, RHD...read head, d1...radial direction, d2...traveling direction, d3...rotational direction, d5...overwrite direction.

Claims

1. a disk having a plurality of bands each containing a plurality of tracks, each of said tracks containing a plurality of sectors; a write head for writing data onto the disk; a write processing unit that selects a shingled recording format in which data is written to the plurality of tracks in an overwrite direction parallel to the radial direction of the disk, and causes the write head to write data to each of the bands; a determining unit for determining whether or not there is a quality-degraded recording sector in which the quality of recorded data is lower than a reference level among all recording sectors in which data is written in each of the bands; a refresh processing unit that, when it is determined that there is a target band including the quality-deteriorated recording sector among the plurality of bands, reads target data of a plurality of target recording sectors that are targets of refresh among all the recording sectors of the target band, rewrites the target data to the plurality of target recording sectors, and refreshes the plurality of target recording sectors, the plurality of target recording sectors include the quality-degraded recording sector, In the target band, the number of the plurality of target recording sectors is less than the number of all the recording sectors. Magnetic disk device.

2. In the target band, the plurality of target recording sectors are a plurality of recording sectors arranged in the overwrite direction.

2. The magnetic disk drive according to claim 1.

3. the plurality of bands further includes an adjacent band adjacent to the target band in the radial direction, a first track of the adjacent band that is closest to the target band includes one or more recording sectors and remaining unused sectors to which no valid data has been written; In the target band, the plurality of target recording sectors are a plurality of recording sectors aligned with the one or more recording sectors of the first track in the overwrite direction.

2. The magnetic disk drive according to claim 1.

4. a counter that counts the number of writes as k each time data is written to the adjacent band; a recording unit that stores the total number of writes, If the track closest to the adjacent band among the plurality of tracks of the target band is defined as a second track, The determination unit when it is determined that the cumulative total of the number of writes is less than a write count threshold, it is determined that one or more recording sectors of the second track that are aligned with the one or more recording sectors of the first track in the radial direction do not correspond to the quality-deteriorated recording sectors, when it is determined that the cumulative total of the number of writes is equal to or greater than a write count threshold, it is determined that, in the second track, the one or more recording sectors aligned with the one or more recording sectors of the first track in the radial direction correspond to the quality-deteriorated recording sectors, the refresh processing unit resets the cumulative number of write operations in the recording unit when refreshing the plurality of target recording sectors; 4. The magnetic disk drive according to claim 3.

5. a cache for storing received write commands and read commands; a command execution unit that executes the write command and the read command recorded in the cache, When the determination unit determines that the cache is in an idle period in which there are no unexecuted commands, the refresh processing unit refreshes the plurality of target recording sectors during the idle period; 2. The magnetic disk drive according to claim 1.

6. Among the plurality of tracks of the target band, The track onto which data is first written in the shingled recording format is designated as the second track, The track on which the data is written last is the third track. If a track different from the second track and including the quality-degraded recording sector is designated as a fourth track, In the target band, the target recording sectors are all recording sectors of a plurality of tracks from the fourth track to the third track in the overwrite direction.

2. The magnetic disk drive according to claim 1.

7. Among the plurality of tracks of the target band, The track onto which data is first written in the shingled recording format is designated as the second track, The track on which the data is written last is the third track. If a track different from the second track and including the quality-degraded recording sector is designated as a fourth track, In the target band, the plurality of target recording sectors are a plurality of recording sectors aligned in the overwrite direction from the quality-deteriorated recording sector of the fourth track to the recording sector of the third track.

2. The magnetic disk drive according to claim 1.

8. the quality of the data recorded in the recording sector of the band is the bit error rate of the data; the bit error rate of the data recorded in the quality-degraded recording sector, which is also the bit error rate of the data having quality lower than the reference level, is higher than the reference value; the bit error rate of data having quality equal to or higher than the reference level is equal to or lower than the reference value; the determining unit determines whether or not there is a quality-degraded recording sector in which a bit error rate of recorded data is higher than the reference value among all the recording sectors in which data is written in each of the bands.

2. The magnetic disk drive according to claim 1.

9. a read head for reading data from the disk; a read processing unit that causes the read head to read data from the disk; a detector for detecting the number of times the same data on the disk is read by the read processor; the number of times data having a quality lower than the reference level is read, and the number of times data recorded in the quality-degraded recording sector is read is greater than the reference number; the number of times data having quality equal to or higher than the reference level is read is equal to or less than the reference number of times; the determining unit determines whether or not there is a quality-deteriorated recording sector in which the number of times the recorded data has been read is greater than the reference number of times among all the recording sectors in which data is written in each of the bands; 2. The magnetic disk drive according to claim 1.

10. the write head is a magnetic head for energy-assisted recording that performs energy-assisted recording, 2. The magnetic disk drive according to claim 1.

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