Magnetic disk device

Abstract

The embodiment of the invention relates to a magnetic disk device. A magnetic disk device includes a disk, a write head, a write processing unit that selects a shingled recording type and causes the write head to execute writing of data to each tape (BA), a determination unit, and a refresh processing unit. The determination unit determines whether or not a quality degradation recording sector (DRSC) exists in all recording sectors (RSC) in each band (BA). And a refresh processing unit that refreshes the plurality of target recording sectors (TSC) when it is determined that there is a target band (TBA) including the quality degradation recording sector (DRSC) among the plurality of bands (BA). The plurality of object recording sectors (TSC) includes a quality degradation recording sector (DRSC). In the object tape (TBA), the number of the plurality of object recording sectors (TSC) is smaller than the number of all recording sectors (RSC).

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2024-020342 (filing date: February 14, 2024), the entire contents of which are incorporated herein by reference. Technical Field

[0002] An embodiment of the present invention relates to a magnetic disk device. Background Art

[0003] As magnetic disk devices, there are known conventional recording (CMR) type (or previous recording type) magnetic disk devices that write to multiple tracks at intervals in the radial direction of the disk, shingled recording (SMR, or Shingled Write Recording: SWR) type magnetic disk devices that write to multiple tracks in an overlapping manner in the radial direction of the disk, and hybrid recording type magnetic disk devices that select and execute both conventional recording type and shingled recording type. Summary of the Invention

[0004] A magnetic disk device according to one embodiment comprises: 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 type for writing data overlappingly to the plurality of tracks in an overlapping writing direction parallel to a radial direction of the disk, and causing the write head to write data to each of the bands; a judgment unit for judging whether, in each of the bands, among all the recording sectors in which data is written, there are quality-degraded recording sectors in which the quality of the recorded data is lower than a reference level; and a refresh processing unit for, when it is judged that there is an object band including the quality-degraded recording sectors within the plurality of bands, reading object data of a plurality of object recording sectors as refresh objects from among all the recording sectors of the object band, rewriting the object data to the plurality of object recording sectors, and refreshing the plurality of object recording sectors; the plurality of object recording sectors including the quality-degraded recording sectors, and the number of the plurality of object recording sectors in the object band being less than the number of all the recording sectors.

[0005] According to this embodiment, it is possible to provide a magnetic disk device capable of suppressing wear of a write head. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a block diagram showing the configuration of a magnetic disk device according to one embodiment.

[0007] Figure 2This is a perspective view showing a portion of the magnetic disk device, showing a plurality of disks and a plurality of heads.

[0008] Figure 3 This is a schematic diagram showing an example of the arrangement of a plurality of servo areas and a plurality of data areas on a single disk according to the above-described embodiment.

[0009] Figure 4 Is to show the progress Figure 3 Schematic diagram of the three tracks and write head in the user data area of the disk shown in the shingled recording process.

[0010] Figure 5 Is to show the Figure 3 Schematic diagram of a typical recording process of a disk showing three tracks of a media cache and a write head.

[0011] Figure 6 This is a schematic diagram showing an example of data writing processing on a disk.

[0012] Figure 7 It shows Figure 6 Schematic diagram of 2 bands and 1 guard band in the user data area.

[0013] Figure 8 It shows Figure 6 Schematic diagram of 3 sectors in 1 track of the tape shown.

[0014] Figure 9 It shows Figure 7 The schematic diagram of the two bands and one guard band shown is for explaining the refresh processing method according to Example 1 of the above-mentioned embodiment.

[0015] Figure 10 It shows Figure 7 The schematic diagram of the two bands and one guard band shown is for explaining the refresh processing method according to Comparative Example 1.

[0016] Figure 11 It shows Figure 7 The schematic diagrams of the two bands and one guard band shown are 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.

[0017] Figure 12 It shows Figure 7 The schematic diagram of the two bands and one guard band shown is for explaining the refresh processing method according to Comparative Example 2.

[0018] Figure 13 It shows Figure 7The schematic diagram of the two bands and one guard band shown is for explaining the refresh processing method according to Example 3 of the above-mentioned embodiment.

[0019] Figure 14 It shows Figure 7 The schematic diagrams of the two bands and one guard band shown are for explaining the refresh processing method according to Example 4 of the above-mentioned embodiment and the refresh processing method according to Example 6 of the above-mentioned embodiment.

[0020] Description of labels

[0021] 1…Disk drive, 60…MPU, 61…Read / write processing unit, 61a…Write processing unit, 61b…Read processing unit, 62…Judgment unit, 63…Refresh processing unit, 64…Counter, 65…Instruction execution unit, 66…Detection unit, 70…Volatile memory, 80…Buffer memory, 81…Cache memory, 90…Non-volatile 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…segment, BA…band, TBA…object band, ABA…adjacent band, STR…track, SC…sector, RSC…recording sector, TSC…object recording sector, DRSC…quality deteriorated recording sector, VSC…unused sector, GB…guard band, GTR…guard track, WHD…write head, RHD…read head, d1…radial direction, d2…travel direction, d3…rotation direction, d5…overlap writing direction. DETAILED DESCRIPTION

[0022] (One embodiment)

[0023] Hereinafter, a magnetic disk device 1 according to an 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 This is a block diagram showing the configuration of a magnetic disk device 1 according to this embodiment. In this embodiment, magnetic disk device 1 is a hybrid recording type magnetic disk device that selects and performs both a normal recording type and a shingled recording type. However, the technology described below can also be applied to shingled recording type magnetic disk devices.

[0024] like Figure 1As shown, a magnetic disk drive 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 a head amplifier IC or preamplifier) 130, a volatile memory 70, a buffer memory (buffer) 80, a nonvolatile memory 90, and a system controller 110 as a single-chip integrated circuit. Furthermore, the magnetic disk drive 1 is connected to a host system (hereinafter simply referred to as a host) 100.

[0025] Each disk DK has a diameter of, for example, 97 mm (3.8 inches) and has recording layers (magnetic recording layers) 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 thereto.

[0026] The head stack assembly 22 can control the head HD mounted on the arm 30 to move to a target position on the disk DK by driving a voice coil motor (hereinafter referred to as VCM) 24 , that is, can perform seek.

[0027] In the data-writable area of the disc DK, there are allocated 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.

[0028] The head HD records and reproduces information on the disk DK. The head HD is primarily composed of a slider and includes a write head WHD and a read head RHD mounted on the slider. The write head WHD writes data to the recording layer of the disk DK. The read head RHD reads data from the data tracks on the recording layer of the disk DK.

[0029] The driver IC 120 controls the driving of the SPM 20 and the VCM 24 under the control of the system controller 110 (more specifically, the MPU 60 described later). The SPM 20 supports and rotates a plurality of disks DK.

[0030] The head amplifier IC 130 includes a read amplifier and a write driver. The read amplifier amplifies the read signal from the disk DK and outputs it to the system controller 110 (specifically, the read / write (R / W) channel 140 described later). The write driver outputs a write current to the head HD in response to the signal output from the R / W channel 140.

[0031] Volatile memory 70 is a semiconductor memory that loses stored data when power is cut off. It stores data required for processing within various components of magnetic disk drive 1. Examples of volatile memory 70 include DRAM (Dynamic Random Access Memory) and SDRAM (Synchronous Dynamic Random Access Memory).

[0032] The buffer memory 80 is a semiconductor memory that temporarily stores data exchanged between the magnetic disk drive 1 and the host computer 100. Alternatively, the buffer memory 80 may be integrally formed with the volatile memory 70. Examples of the buffer memory 80 include DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), and MRAM (Magnetoresistive Random Access Memory).

[0033] The buffer memory 80 includes a cache memory 81. The cache memory 81 includes a first area used as a read cache and a second area used as a write cache, and temporarily stores commands received from the host 100. The first area of the cache memory 81 temporarily stores read commands received from the host 100. The second area of the cache memory 81 temporarily stores write data including write commands received from the host 100 and user data corresponding to the write commands.

[0034] The nonvolatile memory 90 is a semiconductor memory that records stored data even when power is cut off. The nonvolatile memory 90 is, for example, a NOR-type or NAND-type flash ROM (Flash Read Only Memory: FROM).

[0035] The system controller (controller) 110 is implemented, for example, using a large-scale integrated circuit (LSI) known as a system-on-a-chip (SoC), in which multiple components are integrated into 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 nonvolatile memory 90, and a host computer 100.

[0036] The R / W channel 140 performs signal processing for data read from the disk DK and data written from the host 100, based on instructions from the MPU 60 (described later). The R / W channel 140 includes circuitry or functions for modulating write data. It also includes circuitry or functions for measuring the signal quality of read data. The R / W channel 140 is electrically connected to, for example, the head amplifier IC 130, the HDC 150, and the MPU 60.

[0037] The HDC 150 controls data transfer between the host 100 and the R / W channel 140 according to instructions from the MPU 60 described later. The HDC 150 is electrically connected to the R / W channel 140, the MPU 60, the volatile memory 70, the buffer memory 80, the nonvolatile memory 90, and the like.

[0038] The MPU 60 is a control unit that controls various components of the magnetic disk drive 1 and serves as a main controller. The MPU 60 controls the VCM 24 via the driver IC 120 and performs servo control to position the head HD. The MPU 60 controls the write operation of data to the disk DK and selects the storage destination for write data transmitted from the host 100. Furthermore, the MPU 60 controls the read operation of data from the disk DK and controls the processing of read data transmitted from the disk DK to the host 100. The MPU 60 is connected to various components of the magnetic disk drive 1. For example, the MPU 60 is electrically connected to the driver IC 120, the R / W channel 140, the HDC 150, and the like.

[0039] The MPU 60 includes a read / write processing unit 61, a determination unit 62, a refresh processing unit 63, a counter 64, an instruction execution unit 65, a detection unit 66, and the like. The MPU 60 executes the processing of each of these units, such as the read / write processing unit 61, the determination unit 62, the refresh processing unit 63, the counter 64, the instruction execution unit 65, and the detection unit 66, in firmware. Alternatively, the MPU 60 may include these units as circuits.

[0040] The read / write processing unit 61 includes a write processing unit 61a and a read processing unit 61b. In response to commands from the host computer 100, the write processing unit 61a controls data writing, while the read processing unit 61b controls data reading, 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, positioning the head HD at a target position (predetermined radial position) on the disk DK to perform a read or write process.

[0041] Figure 2 1 is a perspective view showing a portion of the magnetic disk device 1 , showing a plurality of disks DK and a plurality of heads HD.

[0042] like Figure 2 As shown in FIG, in the circumferential direction, the rotation direction of the disk DK is referred to as the rotation direction d3. Figure 2 In the example shown, the rotation direction is counterclockwise, but the opposite direction (clockwise) is also possible. Furthermore, the travel direction d2 of the head HD relative to the disk DK is opposite to the rotation direction d3. The travel direction d2 is the direction in which the head HD sequentially writes and reads data from the disk DK in the circumferential direction, that is, the direction in which the head HD travels relative to the disk DK in the circumferential direction.

[0043] The magnetic disk device 1 includes i disks DK1 to DKi and j heads HD1 to HDj. In this embodiment, the number of heads HD is twice the number of disks DK (j=2×i).

[0044] Disks DK1-DKi are coaxially arranged and overlapped with each other at intervals. Disks DK1-DKi have the same diameter. Here, the terms "same," "identical," "identical," and "equivalent" encompass both completely identical and different enough to be considered substantially identical. Furthermore, disks DK1-DKi may have different diameters.

[0045] Each disk DK has recording layers L on both sides. For example, disk DK1 has a first recording layer La1 and a second recording layer Lb1 on the opposite side of the first recording layer La1. Disk DK2 has a first recording layer La2 and a second recording layer Lb2 on the opposite side of the first recording layer La2. Disk DKi has a first recording layer Lai and a second recording layer Lbi on the opposite side of the first recording layer Lai. Each first recording layer La is sometimes referred to as a front surface or a recording surface. Each second recording layer Lb is sometimes referred to as a back surface or a recording surface.

[0046] Each recording layer L includes a user data area U and a system area S. The first recording layer La1 includes a user data area Ua1 and a system area Sa1. The second recording layer Lb1 includes a user data area Ub1 and a system area Sb1. The first recording layer La2 includes a user data area Ua2 and a system area Sa2. The second recording layer Lb2 includes a user data area Ub2 and a system area Sb2. The first recording layer Lai includes a user data area Uai and a system area Sai. The second recording layer Lbi includes a user data area Ubi and a system area Sbi.

[0047] The track enclosed by the double dashed line in the user data area Ua1 (first recording layer La1) is referred to as track Ta1. The track located on the opposite side of track Ta1 in the user data area Ub1 (second recording layer Lb1) is referred to as track Tb1.

[0048] The track enclosed by the double dashed line in the user data area Ua2 (first recording layer La2) is referred to as track Tc1. The track located on the opposite side of track Tc1 in the user data area Ub2 (second recording layer Lb2) is referred to as track Td1.

[0049] The track enclosed by the double dashed line in the user data area Uai (first recording layer Lai) is referred to as track Te1. The track located on the opposite side of track Te1 in the user data area Ubi (second recording layer Lbi) is referred to as track Tf1.

[0050] In this embodiment, the tracks Ta1, Tb1, Tc1, Td1, Te1, and Tf1 are located on the same cylinder.

[0051] The head HD faces the disk DK. In this embodiment, one head HD faces each recording layer L of the disk DK. For example, the head HD1 faces the first recording layer La1 of the disk DK1, writing data to the first recording layer La1 and reading data from the first recording layer La1. The head HD2 faces the second recording layer Lb1 of the disk DK1, writing data to the second recording layer Lb1 and reading data from the second recording layer Lb1.

[0052] Head HD3 faces the first recording layer La2 of disk DK2, writing data to and reading data from the first recording layer La2. Head HD4 faces the second recording layer Lb2 of disk DK2, writing data to and reading data from the second recording layer Lb2. Head HDj-1 faces the first recording layer Lai of disk DKi, writing data to and reading data from the first recording layer Lai. Head HDj faces the second recording layer Lbi of disk DKi, writing data to and reading data from the second recording layer Lbi.

[0053] Figure 3 1 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 a disk DK according to this embodiment. Figure 3 As shown, in the radial direction d1 of the disk DK, the direction toward the outer periphery of the disk DK is called the outer direction (outer side), and the direction opposite to the outer direction is called the inner direction (inner side).

[0054] exist Figure 3 In the example, the user data area U is divided into an inner peripheral area IR located inward, an outer peripheral area OR located outward, and a middle peripheral area MR located between the inner peripheral area IR and the outer peripheral area OR.

[0055] The disk DK has multiple servo areas SV and multiple data areas DTR. For example, the multiple servo areas SV may extend radially in the radial direction of the disk DK and be discretely arranged at predetermined intervals in the circumferential direction. For example, the multiple servo areas SV may extend linearly from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. For example, the multiple servo areas SV may extend spirally from the inner circumference to the outer circumference and be discretely arranged at predetermined intervals in the circumferential direction. Furthermore, the multiple servo areas SV may be arranged in an island shape in the radial direction and discretely arranged at predetermined intervals in the circumferential direction.

[0056] Hereinafter, a servo area SV in a predetermined track may also be referred to as a "servo sector." Furthermore, 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 pieces of servo data constituting a servo sector" may also be referred to as a "servo pattern." Furthermore, "servo data written to a servo sector" may also be referred to as a "servo sector."

[0057] A plurality of data areas DTR are respectively arranged between a plurality of servo areas SV. For example, the data area DTR is equivalent to the area between two consecutive servo areas SV in the circumferential direction. Hereinafter, a data area DTR in a predetermined track is sometimes referred to as a "data sector". In addition, a "data area DTR" is sometimes referred to as a "data sector DTR". A data sector contains user data. In addition, "user data written to a data sector" is sometimes referred to as a "data sector". A "data sector" is sometimes referred to as "user data". In addition, a "pattern composed of several data" is sometimes referred to as a "data pattern". In Figure 3 In the example shown, the data pattern of a predetermined track is composed of a plurality of servo data (servo sectors) and a plurality of user data (data sectors).

[0058] The servo area SV includes multiple segment servo areas ZSV, etc. Furthermore, in addition to the segment servo areas ZSV, the servo area SV may also include an area containing a gap (a circumferential positional offset between two segment servo areas), an area containing servo data, and a data area DTR. The multiple segment servo areas ZSV are discretely arranged along the radial direction. Each of the multiple segment servo areas ZSV extends in the radial direction.

[0059] A segment servo area (servo area) ZSV in a predetermined track is sometimes referred to as a "segment servo sector" or "servo sector." Furthermore, a "segment servo area (servo area) ZSV" is sometimes referred to as a "segment servo sector ZSV" or "servo sector ZSV." "Servo data written to a segment servo sector" is sometimes referred to as a "segment servo sector" or "servo sector." Hereinafter, "the configuration of several servo data constituting a segment servo sector" is sometimes referred to as a "segment servo pattern" or "servo pattern." Hereinafter, a servo area SV in a predetermined track is sometimes referred to as a "segment pattern sector."

[0060] Furthermore, a "servo area SV" is sometimes referred to as a "segment pattern sector." "At least one piece of data written to a segment pattern sector" is sometimes referred to as a "segment pattern sector." A segment pattern sector includes at least one segment servo sector. Hereinafter, "the data pattern of a segment pattern sector" is sometimes referred to as a "segment data pattern."

[0061] exist Figure 3 In the example shown, the servo area SV includes segment servo areas ZSV0, ZSV1, and ZSV2. The segment servo areas ZSV0, ZSV1, and ZSV2 are arranged in a staggered manner in the radial direction. Alternatively, the segment servo areas ZSV0, ZSV1, and ZSV2 may be arranged in a stepped manner in the radial direction.

[0062] Segment servo area ZSV2 is located on the inner circumference side of segment servo area ZSV1. Segment servo area ZSV0 is located on the outer circumference side of segment servo area ZSV1. For example, segment servo area ZSV2 is arranged from inner circumference area IR to mid-circumference area MR, segment servo area ZSV1 is arranged from inner circumference area IR to outer circumference area OR, and segment servo area ZSV0 is arranged from mid-circumference area MR to outer circumference area OR. Hereinafter, within the predetermined servo area SV, the predetermined radial area in which multiple segment servo areas ZSV are arranged in the circumferential direction may also be referred to as a segment servo boundary area, a dual servo area, or a dual segment servo area ZB.

[0063] exist Figure 3In the example shown, master servo areas SVO and slave servo areas SVE are alternately arranged at intervals in the circumferential direction. For example, one slave servo area SVE is arranged between two master servo areas SVO that are arranged consecutively at intervals in the circumferential direction. In other words, one slave servo area SVE is arranged between two master servo areas SVO that are arranged consecutively at intervals in the circumferential direction. For example, if all servo areas SV on the disk DK are sequentially numbered, the master servo area SVO corresponds to the odd-numbered servo areas SV, and the slave servo area SVE corresponds to the even-numbered servo areas SV. Alternatively, two or more slave servo areas SVE may be arranged between two master servo areas SVO that are arranged consecutively at intervals in the circumferential direction.

[0064] The master servo area SVO and the slave servo area SVE may, for example, consist solely of servo areas (hereinafter sometimes referred to as normal servo areas) from which servo data is read and demodulated in its entirety. "Reading and demodulating servo data" may also be referred to as "servo reading" in the following. The master servo area SVO and the slave servo area SVE may, for example, consist solely of a normal servo area and a servo area (hereinafter sometimes referred to as a short servo area) from which servo data is read over a smaller circumferential range than the circumferential range of servo data read in the normal servo area.

[0065] The disk DK is allocated with a media cache M. However, the media cache M does not need to be arranged on the disk DK.

[0066] By using the above-described plurality of servo data, the head HD can be positioned so as to obtain a predetermined off-track amount, for example.

[0067] This embodiment describes a case where the number of sessions on a disk DK is three. However, the number of sessions on a disk DK can be varied in various ways. Alternatively, the number of sessions on a disk DK can be 30 to 40. Furthermore, each session can have multiple bands. For example, each session can have hundreds of bands.

[0068] Figure 4 Is to show the Figure 3 The diagram shows three tracks STR and a write head WHD in the user data area U of a disk DK undergoing shingled recording. The user data area U is a shingled recording area. Within the user data area U, data can be written sequentially in bands, i.e., shingled recording is permitted.

[0069] like Figure 4 As shown, the write head WHD can sequentially write data to the disk DK in the travel direction d2. Figure 3The shown read head RHD is also capable of reading data written to the disc DK sequentially in the direction of travel d2.

[0070] The direction in which a plurality of tracks STR are continuously recorded in a shingled manner in a direction parallel to the radial direction d1, that is, the direction in which the next track STR to be written overlaps the previous track STR written in the radial direction d1 is called the overlapping writing direction or the recording advancing direction. Figure 4 In the band BAe shown, the overlap writing direction d5 is the inner direction, but the overlap writing direction may also be the outer direction.

[0071] For example, the overlapping writing direction applied to multiple bands BA (multiple segments Z) located on the outer side of a specific radial position and the overlapping writing direction applied to multiple bands BA (multiple segments Z) located on the inner side of the above-mentioned specific radial position can also be opposite to each other.

[0072] Band BAe includes a plurality of tracks STR, including tracks STRe, STRe+1, and STRe+2. Tracks STRe, STRe+1, and STRe+2 are overlap-written sequentially in the overlap-write direction d5 in the order described above. Of the tracks STRe, STRe+1, and STRe+2, track STRe is the first track to be written, and track STRe+2 is the last track to be written.

[0073] Track STRe, when no overlap writing is performed on other tracks, has a track center STCe at the center in the radial direction d1. Track STRe+1, when no overlap writing is performed on other tracks, has a track center STCe+1 at the center in the radial direction d1. Track STRe+2, when no overlap writing is performed on other tracks, has a track center STCe+2 at the center in the radial direction d1.

[0074] exist Figure 4 In the example shown, tracks STRe, STRe+1, and STRe+2 are written at a pitch (shingled recording track pitch) of STP. The center of track STRe (STCe) is spaced apart from the center of track STRe+1 (STCe+1) by a pitch of STP in the radial direction d1. The center of track STRe+1 (STCe+1) is spaced apart from the center of track STRe+2 (STCe+2) by a pitch of STP in the radial direction d1. Tracks STRe through STRe+2 can also be written at different pitches.

[0075] The width in the radial direction d1 of the area in track STRe where the overlapping writing of track STRe+1 is not performed is the same as the width in the radial direction d1 of the area in track STRe+1 where the overlapping writing of track STRe+2 is not performed. In addition, the width in the radial direction d1 of the area in track STRe where the overlapping writing of track STRe+1 is not performed may be different from the width in the radial direction d1 of the area in track STRe+1 where the overlapping writing of track STRe+2 is not performed.

[0076] exist Figure 4 In the figure, for the sake of convenience, each track STR is shown as a rectangular shape, but in fact, each track STR is curved along the circumferential direction. In addition, each track STR can also be a wave shape that varies in the radial direction d1 while extending in the circumferential direction. Figure 4 In the example, overlapping writing is performed on three tracks STR, but overlapping writing can also be performed on two tracks STR, and overlapping writing can also be performed on more than three tracks STR.

[0077] The write processing unit 61a can select the shingled recording type in which data is written in an overlapping manner to a plurality of tracks STR in the overlap writing direction d5, and cause the write head WHD to write data to each band BA. Figure 4 In the example shown, the write processing unit 61a sequentially performs shingled recording on tracks STRe to STRe+2 (in the overlapping writing direction d5) in the inward direction of the band BAe at a pitch STP. Since data is written in the user data area U using shingled recording, the recording density of the user data area U can be improved.

[0078] The write processing unit 61a writes to track STRe+1 at a pitch STP in the inner direction of track STRe, and overlaps track STRe+1 on a portion of the inner circumference of track STRe. The write processing unit 61a writes to track STRe+2 at a pitch STP in the inner direction of track STRe+1, and overlaps track STRe+2 on a portion of the inner circumference of track STRe+1.

[0079] Figure 5 Is to show the Figure 3 Schematic diagram of the three tracks CTR of the media cache M and the write head WHD of the normal recording process of the disk DK shown. Figure 3 The system area S shown is a normal recording area. In the media cache M and the system area S, data can be written randomly, that is, normal recording is allowed.

[0080] like Figure 5As shown, the media cache M has multiple tracks CTR, including tracks CTRe, CTRe+1, and CTRe+2. For example, the widths (track widths) of tracks CTRe, CTRe+1, and CTRe+2 in the radial direction d1 are the same. Alternatively, the track widths of tracks CTRe through CTRe+2 may be different.

[0081] The track CTRe has a track center CTCe at the center of the radial direction d1, the track CTRe+1 has a track center CTCe+1 at the center of the radial direction d1, and the track CTRe+2 has a track center CTCe+2 at the center of the radial direction d1. Figure 5 In the example shown, tracks CTRe, CTRe+1, and CTRe+2 are written at a pitch (normal recording track pitch) CTP. The track center CTCe of track CTRe is spaced apart from the track center CTCe+1 of track CTRe+1 by the pitch CTP. The track center CTCe+1 of track CTRe+1 is spaced apart from the track center CTCe+2 of track CTRe+2 by the pitch CTP.

[0082] Track CTRe and track CTRe+1 are separated by a gap GP. Track CTRe+1 and track CTRe+2 are separated by a gap GP. In addition, tracks CTRe to CTRe+2 can also be written at different intervals. Figure 5 In the figure, for the sake of convenience, each track CTR is shown as a rectangular shape, but in reality, each track CTR is curved along the circumferential direction. In addition, each track CTR may be a wave shape that varies in the radial direction d1 while extending in the circumferential direction.

[0083] The write processing unit 61a can select a normal recording mode for writing data to a plurality of tracks CTR at intervals in the radial direction d1 of the disk DK and execute the write processing. Figure 4 In the example shown, 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.

[0084] The write processing unit 61a positions the write head WHD at the track center CTCe+1, which is separated inwardly from the track center CTCe of the track CTRe by a 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 the track center CTCe+2, which is separated inwardly from the track center CTCe+1 of the track CTRe+1 by a pitch CTP, and performs normal recording on the track CTRe+2 or a predetermined sector of the track CTRe+2.

[0085] The write processing unit 61a can normally record tracks CTRe, CTRe+1 and CTRe+2 sequentially in a predetermined area of the disk DK, or can normally record predetermined sectors of track CTRe, predetermined sectors of track CTRe+1 and predetermined sectors of track CTRe+2 in a random manner.

[0086] Figure 6 1 is a schematic diagram showing an example of data writing processing in the disk DK. Figure 6 As shown, the user data area U includes bands BAa, BAb, and BAc. Bands BAa, BAb, and BAc belong to the same zone Ze. In the zone Ze, bands BAa, BAb, and BAc are intermittently arranged in the overlap writing direction in the order described above.

[0087] The bands BAa and BAb are adjacent to each other in the radial direction d1 , and the bands BAb and BAc are adjacent to each other in the radial direction d1 .

[0088] Band BAa includes x tracks: STRa0, STRa1, STRa2, ..., STRa(x-3), STRa(x-2), and STRa(x-1). Tracks STRa0 through STRa(x-1) are shingled in the overlap writing direction d5 in the order described above. In band BAa, track STRa0 corresponds to the leading track to which data is first written, and track STRa(x-1) corresponds to the trailing track to which data is last written.

[0089] Band BAb includes x tracks: tracks STRb0, STRb1, STRb2, ..., STRb(x-3), STRb(x-2), and STRb(x-1). Tracks STRb0 through STRb(x-1) are shingled in the overlap writing direction d5 in the order described above. In band BAb, track STRb0 corresponds to the leading track to which data is first written, and track STRb(x-1) corresponds to the trailing track to which data is last written.

[0090] Band BAc includes tracks STRc0, STRc1, STRc2, ..., STRc(x-3), STRc(x-2), and STRc(x-1). Tracks STRc0 through STRc(x-1) are shingled in the overlap writing direction d5 in the order described above. In band BAc, track STRc0 corresponds to the leading track to which data is first written, and track STRc(x-1) corresponds to the trailing track to which data is last written.

[0091] 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 in each band BA is fixed in each zone Z. In this example, each band BA belonging to zone Ze has x tracks STR.

[0092] exist Figure 6 In FIG, tracks CTR(x-2) and CTR(x-1) are shown. Figure 6 In the example, tracks CTR(x-2) and CTR(x-1) are normally 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.

[0093] Figure 7 It shows Figure 6 FIG. 1 is a schematic diagram showing two bands BAa, BAb and one guard band GB in the user data area U. Figure 7 As shown, in the shingled recording method, unlike the normal recording method, due to the characteristic of performing overlap writing on a part of the track STR, the MPU 60 manages the track group of the user data area U in units called bands.

[0094] A guard band GB is typically provided between adjacent bands BA in the radial direction d1. The guard band GB includes a guard track GTR. Unlike this embodiment, the guard band GB may also include multiple guard tracks GTR. The guard band GB suppresses interference between adjacent bands BA. The guard band GB enables shingled recording per band BA. Furthermore, the guard band GB separates the ranges (bands BA) to be written sequentially.

[0095] 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 protection 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 arranged at equal intervals in the overlapping writing direction d5.

[0096] The recording capacity of each band BA in the user data area U, excluding the guard band GB, is usually predetermined based on user specifications. The MPU 60 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.

[0097] Figure 8It shows Figure 6 Schematic diagram of three sectors SCe, SC(e+1) and SC(e+2) in one track STRa0 with BAa. Figure 8 As shown, each track STR has multiple sectors SC. Track STRa1 has multiple sectors SC including sectors SCe, SC(e+1), and SC(e+2). 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.

[0098] Each sector SC has a length Ls in the circumferential direction of the disk DK.

[0099] The write head WHD is an energy-assisted recording head that performs energy-assisted magnetic recording (EAMR). Examples of energy-assisted recording energy addition methods include microwave-assisted magnetic recording (MAMR) and heat-assisted magnetic recording (HAMR).

[0100] In the MAMR method, an element is placed at the tip of the write head WHD that generates microwaves (high-frequency magnetic fields) when current is applied. The medium, exposed to the high-frequency magnetic field generated by the write head WHD during MAMR recording, undergoes spin resonance, resulting in a magnetic reversal with a weaker magnetic field than would normally be required. This allows for precise data recording with a smaller write head WHD, thereby increasing the recording density of the disk DK.

[0101] Furthermore, the longer the amount of current flowing to the write head WHD increases, the shorter the product life of the write head WHD performing MAMR recording. In other words, the longer the amount of data written to the disk DK increases, the shorter the product life of the write head WHD. Therefore, from the perspective of product life, it is desirable to reduce the amount of data written to the disk DK for the write head WHD.

[0102] In the present embodiment, the write head WHD is configured to utilize energy other than magnetism, but the present invention is not limited thereto. The write head WHD may be a magnetic head not configured to perform energy-assisted recording.

[0103] (Example 1 of one embodiment)

[0104] Next, a refresh processing method according to Example 1 of the above-mentioned embodiment will be described. Figure 9 It shows Figure 7The schematic diagram of the two bands BAa and BAb and the one guard band GB is used to explain the refresh processing method according to the first embodiment.

[0105] exist Figure 9 In the figure, each track STR is shown as a rectangle for ease of explanation, but in reality, each track STR is curved along the circumferential direction. In addition, although multiple tracks STR are arranged in the overlap writing direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overlap writing direction d5 while overlapping.

[0106] In the figure, a dot pattern is added to the recording sector RSC. Unused sectors VSC are shown in solid colors. A diagonal grid pattern is added to the quality-degraded recording sector DRSC within the recording sector RSC instead of the dot pattern. Diagonal lines are added to the target recording sector TSC within the recording sector RSC instead of the dot pattern. Furthermore, the quality-degraded recording sector DRSC is also the target recording sector TSC.

[0107] like Figure 9 As shown, the band number of band BAa is set to "a", and the band number of band BAb is set to "b". The track numbers of each band BA are set to "0" to "x-1". The sector numbers of each track STR are set to "0" to "y-1". In the following, the following symbol "SC (track number, sector number)" is sometimes used to identify the sector SC of each band BA. When identifying the band BA to which the sector SC belongs, the following symbol "SC (band number, track number, sector number)" is sometimes used to identify each sector SC.

[0108] In this embodiment, the band BAb is the target band to be refreshed and is the target band TBA. Meanwhile, the band BAa is adjacent to the band BAb and is upstream of the band BAb in the overlap writing direction d5 and is the adjacent band ABA.

[0109] Among the multiple tracks STR of band BAa, track STRa(x-1), located at the end closest to band BAb, functions as the first track and includes one or more recording sectors RSC in which valid data is written. Furthermore, although track STRa(x-1) may not include unused sectors VSC in which valid data is not written, as in this embodiment, track STRa(x-1) includes unused sectors VSC.

[0110] Among the multiple tracks STRb in band BAb, track STRb0, located closest to band BAa, functions as the second track and is the first track to be written using shingled recording in band BAb. Track STRb(x-1) is the last track to be written using shingled recording in band BAb and functions as the third track.

[0111] In each band BA of segment Ze, all sectors SC of the x-1 tracks STR from 0 to x-2 are sectors with valid data written in them, and are recorded sectors RSC. In the x-1 track STR of each band BA of segment Ze, the five sectors SC from 0 to 4 are sectors with valid data written in them, and are recorded sectors RSC. On the other hand, in the x-1 track STR, the remaining sectors SC from 5 to y-1 are sectors without valid data written in them, and are unused sectors VSC.

[0112] When data is rewritten to track 1 in the shingled user data area U to refresh track 1, track 2, which has been overlapped with track 1, is significantly affected by write blur. Consequently, data must be rewritten to all tracks within the same band BA, including track 2, which has been overlapped.

[0113] Therefore, since the writing time and the amount of written data required for the refresh process of the shingled recording type increase compared to the normal recording type, there is a tendency for the write head WHD to be more severely worn.

[0114] Here, before describing the refresh processing method according to the first embodiment, the refresh processing method according to the first comparative example will be described.

[0115] like Figure 10 As shown, the recording quality of data on band BAb will deteriorate when affected by the following adverse effects: interference when writing data to disk DK, sudden deterioration of the positioning of the write head WHD or change in the floating amount of the write head WHD caused by defects, leakage magnetic field from the write head WHD when writing data to band BAa, etc.

[0116] The adverse effect of the leakage magnetic field from the write head WHD on the band BAb (the effect of ATI (Adjacent Track Interference)) when writing data to the band BAa is greatest when writing data to the track STRa(x-1) of the band BAa. In this example, when writing data to the 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 the track STRa(x-1) of the band BAa, the sectors SC(b, 0, 0), SC(b, 0, 1), SC(b, 0, 2), SC(b, 0, 3), and SC(b, 0, 4) of the track STRb0 of the band BAb are most adversely affected by the leakage magnetic field. Sectors SC(b, 0, 0) to SC(b, 0, 4) of track STRb0 may each become quality-degraded recording sectors DRSC.

[0117] Therefore, it is necessary to perform a refresh process on the band BAb. When performing the refresh process on the band BAb, all recording sectors RSC in the band BAb become target recording sectors TSC to be refreshed. The refresh processing unit 63 can read the target data of multiple target recording sectors TSC (all recording sectors RSC) and rewrite the target data to the multiple target recording sectors TSC to refresh the multiple target recording sectors TSC.

[0118] However, in Figure 10 In the example of , since the amount of data rewriting cannot be reduced when refreshing the band BAb as described above, the write head WHD is severely worn.

[0119] Next, the refresh processing method according to the first embodiment will be described.

[0120] like Figure 9 As shown, when the refresh process is performed on band BAb, not all of the recording sectors RSC of band BAb are set as target recording sectors TSC. The target recording sectors TSC of band BAb are multiple recording sectors RSC arranged in the overlap writing direction d5 with the recording sectors RSC (a, x-1, 0) to RSC (a, x-1, 4) of track STRa (x-1) of band BAa.

[0121] By excluding multiple recording sectors RSC in the band BAb that are arranged in the overlapping writing direction d5 with the recording sectors RSC(a, x-1, 5) to RSC(a, x-1, y-1) of the track STRa(x-1) from the object recording sector TSC, the amount of data rewriting when refreshing the band BAb can be reduced accordingly, and the loss of the write head WHD can be suppressed.

[0122] Next, the refresh processing method according to the first embodiment will be described in detail.

[0123] like Figure 1 and Figure 9 As shown, the determination unit 62 determines whether or not, in each band BA, among all the 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 the reference level.

[0124] When the judgment unit 62 determines that there is an object band TBA containing quality-degraded recording sectors DRSC within multiple bands BA, the refresh processing unit 63 can read the object data of multiple object recording sectors TSC that are refresh objects in all the recording sectors RSC of the object band TBA (band BAb), rewrite the above object data to the above multiple object recording sectors TSC, and refresh the above multiple object recording sectors TSC.

[0125] The multiple target recording sectors TSC include quality-degraded recording sectors DRSC. In this example, the quality-degraded recording sectors DRSC are the five recording sectors RSC (b, 0, 0) to RSC (b, 0, 4) of track STRb0. In the target band TBA (band BAb), the number of the multiple target recording sectors TSC is less than the total number of recording sectors RSC. Because the number of the multiple target recording sectors TSC does not match the total number of recording sectors RSC, the amount of data rewritten when refreshing band BAb can be reduced, thereby suppressing wear on the write head WHD.

[0126] Furthermore, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC arranged in the overlapping write direction d5. In the overlapping write direction d5, the recording sector RSC aligned with the quality-degraded recording sector DRSC is set as the target recording sector TSC, while the recording sector RSC not aligned with the quality-degraded recording sector DRSC is not set as the target recording sector TSC. This allows the target recording sector TSC to be limited (filtered) from all the recording sector RSCs in the target band TBA. This further reduces the amount of data rewritten when refreshing the band BAb, and suppresses wear on the write head WHD.

[0127] Furthermore, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC aligned with one or more recording sectors RSC of track STRa(x-1) in the overlap writing direction d5. In this example, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC aligned with recording sectors RSC(a, x-1, 0) to RSC(a, x-1, 4) of track STRa(x-1) in the overlap writing direction d5. Therefore, the target band TBA (band BAb) can be refreshed while taking into account the adverse effects of the ATI from the last track STRa(x-1) of the adjacent band ABA (band BAa).

[0128] Furthermore, the refresh processing method of the first embodiment can refresh the target zone TBA (zone BAb) in consideration of the number of writes to the adjacent zone ABA (zone BAa).

[0129] Each time data is written to the adjacent band ABA (band BAa), the counter 64 counts the number of writes to k. For example, k = 1. However, the value of k can be less than 1 or even greater than 1. The nonvolatile memory 90 functions as a recording unit and can store the cumulative number of writes. The recording unit is not limited to the nonvolatile memory 90; any unit capable of storing the cumulative number of writes may also be a third memory (not shown).

[0130] The judgment unit 62 can judge that one or more recording sectors RSC in track STRb0 that are aligned with one or more recording sectors RSC of track STRa(x-1) in the radial direction d1 do not conform to the quality-degraded recording sectors DRSC, if the cumulative number of writes to the adjacent band ABA (band BAa) is less than the write number threshold. Here, the judgment unit 62 can judge that the multiple recording sectors RSC(b, 0, 0) to RSC(b, 0, 4) of track STRb0 that are aligned with the multiple 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 conform to the quality-degraded recording sectors DRSC.

[0131] The threshold value of the number of write operations is 200 (times) as an example. The threshold value of the number of write operations can be changed in various ways.

[0132] On the other hand, when the determination unit 62 determines that the cumulative number of writes to the adjacent band ABA (band BAa) is greater than the write number threshold, it can determine that one or more recording sectors RSC in track STRb0 that are aligned with one or more recording sectors RSC of track STRa(x-1) in the radial direction d1 respectively conform to the quality-degraded recording sectors DRSC. Here, the determination unit 62 can determine that the multiple recording sectors RSC(b,0,0) to RSC(b,0,4) of track STRb0 that are aligned with the multiple recording sectors RSC(a,x-1,0) to RSC(a,x-1,4) of track STRa(x-1) in the radial direction d1 respectively conform to the quality-degraded recording sectors DRSC.

[0133] In this case, when refreshing a plurality of target recording sectors TSC, the refresh processing unit 63 can reset the accumulated number of write times in the nonvolatile memory (recording unit) 90. This allows the refresh target band TBA (band BAb) to continue.

[0134] (Example 2 of one embodiment)

[0135] Next, a refresh processing method according to Example 2 of the above-mentioned embodiment will be described. Figure 11 It shows Figure 7 The schematic diagram of the two bands BAa and BAb and the one guard band GB is used to explain the refresh processing method according to the second embodiment.

[0136] exist Figure 11 In the figure, each track STR is shown as a rectangle for ease of explanation, but in reality, each track STR is curved along the circumferential direction. In addition, although multiple tracks STR are arranged in the overlap writing direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overlap writing direction d5 while overlapping.

[0137] In the figure, a dot pattern is added to the recording sector RSC. Unused sectors VSC are shown in solid colors. A diagonal grid pattern is added to the quality-degraded recording sector DRSC within the recording sector RSC instead of the dot pattern. Diagonal lines are added to the target recording sector TSC within the recording sector RSC instead of the dot pattern. Furthermore, the quality-degraded recording sector DRSC is also the target recording sector TSC.

[0138] Here, before describing the refresh processing method according to the second embodiment, the refresh processing method according to the second comparative example will be described.

[0139] like Figure 12As shown, the recording quality of the data in band BAb deteriorates when adversely affected by disturbances during data writing to disk DK, sudden deterioration of the positioning of the write head WHD due to defects, or changes in the floating amount of the write head WHD. In this example, recording sectors RSC(b,5,1) and RSC(b,3,6) of band BAb are quality-deteriorated recording sectors DRSC, respectively.

[0140] Therefore, it is necessary to perform a refresh process on the band BAb. When performing a refresh process on the band BAb, all recording sectors RSC in the band BAb become target recording sectors TSC to be refreshed. The refresh processing unit 63 can read the target data of multiple target recording sectors TSC (all recording sectors RSC), rewrite the target data to the multiple target recording sectors TSC, and refresh the multiple target recording sectors TSC.

[0141] However, in Figure 12 In the example of , since the amount of data rewriting cannot be reduced when refreshing the band BAb as described above, the write head WHD is severely worn.

[0142] Next, the refresh processing method according to the second embodiment will be described.

[0143] like Figure 11 As shown in FIG. 1 , when the refresh process is performed on the band BAb, not all of the recording sectors RSC of the band BAb are set as the target recording sectors TSC. The target recording sectors TSC of the band BAb are the multiple recording sectors RSC arranged with the quality-degraded recording sector DRSC (b, 5, 1) and the multiple recording sectors RSC arranged with the quality-degraded recording sector DRSC (b, 3, 6) in the overlap writing direction d5.

[0144] By excluding all recording sectors RSC of band BAb, including No. 0, 2 to 5, and No. 7 to y-1, from the target recording sector TSC, the amount of data rewriting when refreshing band BAb can be reduced accordingly, and the wear of the write head WHD can be suppressed.

[0145] Next, the refresh processing method according to the second embodiment will be described in detail.

[0146] like Figure 1 and Figure 11As shown, in the target band TBA (band BAb), the multiple target recording sectors TSC are multiple recording sectors RSC arranged in the overlapping writing direction d5. Including the quality-degraded recording sector DRSC (b, 5, 1), the multiple recording sectors RSC from recording sector RSC (b, 0, 1) to recording sector RSC (b, x-1, 1) arranged in the overlapping writing direction d5 are each the target recording sector TSC. In addition, including the quality-degraded recording sector DRSC (b, 3, 6), the multiple recording sectors RSC from recording sector RSC (b, 0, 6) to recording sector RSC (b, x-2, 6) arranged in the overlapping writing direction d5 are also each the target recording sector TSC. It is possible to refresh only the multiple recording sectors RSC arranged in the overlapping writing direction d5, including the quality-degraded recording sector DRSC. This can reduce the amount of data rewriting when refreshing the band BAb, and can suppress the wear of the write head WHD.

[0147] Furthermore, the refresh processing method of the second embodiment can refresh the target band TBA (band BAb) during an idle period, using the cache memory 81, the instruction execution unit 65, and the like.

[0148] 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 idle and there are no unexecuted commands, the refresh processing unit 63 can refresh the plurality of target recording sectors TSC during this idle period. This improves the processing efficiency of the MPU 60 and the utilization efficiency of the head HD including the write head WHD.

[0149] Furthermore, the refresh processing method of the second embodiment can refresh the target zone TBA (zone BAb) in consideration of the bit error rate (BER). In the second embodiment, the quality of data recorded in the recording sector RSC of the zone BA is the bit error rate of the data.

[0150] The bit error rate of data recorded in the quality-degraded recording sector DRSC, which is data with a quality lower than the reference level, is higher than the reference value. On the other hand, the bit error rate of data with a quality higher than the reference level is lower than the reference value. The determination unit 62 can determine whether, in each band BA, among all the recording sectors RSC to which data is written, there are any quality-degraded recording sectors DRSC with recorded data with a bit error rate higher than the reference value.

[0151] In the second embodiment, the determination unit 62 detects that the bit error rate of the data in the recording sector RSC(b,5,1) is higher than the aforementioned reference value, and that the bit error rate of the data in the recording sector RSC(b,3,6) is higher than the aforementioned reference value, and can determine that the recording sectors RSC(b,5,1) and RSC(b,3,6) are respectively quality-degraded recording sectors DRSC. In this way, the bit error rate of the data in the recording sector RSC can be used as an indicator to determine whether the recording sector DRSC is a quality-degraded recording sector.

[0152] (Example 3 of one embodiment)

[0153] Next, a refresh processing method according to Example 3 of the above-mentioned embodiment will be described. Figure 13 It shows Figure 7 The schematic diagram of the two bands BAa and BAb and the one guard band GB is used to explain the refresh processing method according to the third embodiment.

[0154] exist Figure 13 In the figure, each track STR is shown as a rectangle for ease of explanation, but in reality, each track STR is curved along the circumferential direction. In addition, although multiple tracks STR are arranged in the overlap writing direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overlap writing direction d5 while overlapping.

[0155] In the figure, a dot pattern is added to the recording sector RSC. Unused sectors VSC are shown in solid colors. A diagonal grid pattern is added to the quality-degraded recording sector DRSC within the recording sector RSC instead of the dot pattern. Diagonal lines are added to the target recording sector TSC within the recording sector RSC instead of the dot pattern. Furthermore, the quality-degraded recording sector DRSC is also the target recording sector TSC.

[0156] like Figure 13 As shown, track STRb3, which is a track different from track STRb0 and includes quality-deterioration recording sectors DRSC (b, 3, 6), among the multiple tracks STRb in the target band TBA (band BAb), functions as the fourth track. Track STRb5, which is also a track different from track STRb0 and includes quality-deterioration recording sectors DRSC (b, 5, 1), functions as the fourth track. If there are multiple tracks STRb including quality-deterioration recording sectors DRSC in the target band TBA (band BAb), in this third embodiment, track STRb3, which is located furthest upstream in the overlap writing direction d5, among tracks STRb3 and STRb5, can be considered the fourth track as a representative.

[0157] In the target band TBA (band BAb), the target recording sectors TSC are all recording sectors RSC of the multiple tracks STRb, from track STRb3 to track STRb(x-1), in the overlap writing direction d5. In the overlap writing direction d5, the refresh processing is performed on track STRb3, to which the quality-degraded recording sector DRSC(b,3,6) belongs, and the multiple tracks STRb4 to STRb(x-1) downstream of track STRb3 in the band BAb.

[0158] By excluding all recording sectors RSC of tracks STRb 0 to 2 from the target recording sector TSC among all recording sectors RSC of band BAb, the amount of data rewriting when refreshing band BAb can be reduced accordingly, and wear of the write head WHD can be suppressed.

[0159] Furthermore, data can be rewritten to the band BAb starting from the track STRb3 during refresh processing, thereby shortening the time required for the refresh process because data rewriting to the tracks STRb0 to STRb2 is unnecessary.

[0160] (Example 4 of one embodiment)

[0161] Next, a refresh processing method according to Example 4 of the above-mentioned embodiment will be described. Figure 14 It shows Figure 7 The schematic diagram of the two bands BAa and BAb and the one guard band GB is used to explain the refresh processing method according to the fourth embodiment.

[0162] exist Figure 14 In the figure, each track STR is shown as a rectangle for ease of explanation, but in reality, each track STR is curved along the circumferential direction. In addition, although multiple tracks STR are arranged in the overlap writing direction d5 without overlapping, in reality, multiple tracks STR are arranged in the overlap writing direction d5 while overlapping.

[0163] In the figure, a dot pattern is added to the recording sector RSC. Unused sectors VSC are shown in solid colors. A diagonal grid pattern is added to the quality-degraded recording sector DRSC within the recording sector RSC instead of the dot pattern. Diagonal lines are added to the target recording sector TSC within the recording sector RSC instead of the dot pattern. Furthermore, the quality-degraded recording sector DRSC is also the target recording sector TSC.

[0164] like Figure 14As shown, in the target band TBA (band BAb), the plurality of target recording sectors TSC are arranged in the overlap writing direction d5, from the quality-degraded 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 plurality of target recording sectors TSC are arranged in the overlap writing direction d5, from the quality-degraded recording sector DRSC(b, 3, 6) of track STRb3 to the recording sector RSC(b, x-2, 6) of track STRb(x-2).

[0165] Since it is sufficient to rewrite data in a plurality of target recording sectors TSC including the quality-deteriorated recording sector DRSC in the band BAb during refreshing, it is possible to suppress wear of the write head WHD.

[0166] Furthermore, since it is not necessary to rewrite data in the tracks STRb0 to STRb2 when refreshing the band BAb, the time required for the refresh process can be shortened.

[0167] In addition, in the present fourth embodiment, similarly to the above-mentioned second embodiment, the target band TBA (band BAb) can be refreshed during an idle period.

[0168] In addition, in the present fourth embodiment, the target zone TBA (zone BAb) can be refreshed in consideration of the bit error rate, similarly to the above-mentioned second embodiment.

[0169] (Example 5 of one embodiment)

[0170] 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 the above-mentioned Example 2 except for the method described in Example 5.

[0171] like Figure 1 and Figure 11 As shown, in the present fifth embodiment, the target recording sector TSC can also be limited (filtered) from all the recording sectors RSC in the target zone TBA.

[0172] The refresh processing method of the fifth embodiment can refresh the target zone TBA (zone BAb) by considering 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.

[0173] The number of times data recorded in a quality-degraded recording sector DRSC is read is greater than the reference number, which is the number of times data having a quality lower than the reference level is read. On the other hand, the number of times data having a quality higher than the reference level is read is less than the reference number. The determination unit 62 can determine whether, in each band BA, among all the recording sectors RSC in which data is written, there is a quality-degraded recording sector DRSC in which the number of times the recorded data is read is greater than the reference number.

[0174] In the fifth embodiment, the determination unit 62 detects that the number of read attempts for the data in the recording sector RSC(b,5,1) exceeds the aforementioned reference number, and the number of read attempts for the data in the recording sector RSC(b,3,6) exceeds the aforementioned reference number, and can determine that the recording sectors RSC(b,5,1) and RSC(b,3,6) are respectively quality-degraded recording sectors DRSC. In this way, the number of read retries for the data in the recording sector RSC can be used as an indicator to determine whether the recording sector DRSC is a quality-degraded recording sector.

[0175] This fifth embodiment can achieve the same effects as those of the second embodiment.

[0176] (Example 6 of one embodiment)

[0177] 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 the above-mentioned Example 4 except for the method described in Example 6.

[0178] like Figure 1 and Figure 14 As shown, in the sixth embodiment, the target recording sector TSC can also be limited (filtered) from all the recording sectors RSC in the target zone TBA.

[0179] The refresh processing method of this embodiment 6 can refresh the target zone TBA (zone BAb) by considering 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 indicator to determine whether it meets the quality deterioration recording sector DRSC.

[0180] This sixth embodiment can achieve the same effects as those of the fourth embodiment.

[0181] According to a magnetic disk device 1 and a refresh processing method according to an embodiment constructed as described above, the magnetic disk device 1 includes a disk DK, a write head WHD, a write processing unit 61a, a judgment unit 62, and a refresh processing unit 63. The write processing unit 61a can select a shingled recording type and cause the write head WHD to write data to each band BA. The judgment unit 62 can judge whether there are quality-degraded recording sectors DRSC in all recording sectors RSC in each band BA. When it is judged that there is an object band TBA containing quality-degraded recording sectors DRSC in multiple bands BA, the refresh processing unit 63 can read the object data of multiple object recording sectors TSC in all recording sectors RSC of the object band TBA, rewrite the object data to the multiple object recording sectors TSC, and refresh the multiple object recording sectors TSC. The multiple object recording sectors TSC include the quality-degraded recording sector DRSC. In the object band TBA, the number of the multiple object recording sectors TSC is less than the number of all recording sectors RSC.

[0182] Since the amount of data rewritten when refreshing the band BAb can be reduced, the wear of the write head WHD can be suppressed. As described above, the magnetic disk device 1 capable of suppressing the wear of the write head WHD can be obtained.

[0183] While embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. The new embodiments described above can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above embodiments and / or their variations are included within the scope and spirit of the invention, and are included within the invention set forth in the claims and their equivalents.

[0184] For example, the above-described technology is not limited to hybrid recording type magnetic disk devices, but can also be applied to shingled recording type magnetic disk devices.

Claims

1. A magnetic disk device comprising: a disk having a plurality of bands each comprising a plurality of tracks, each of the tracks comprising a plurality of sectors; a write head for writing data to the disk; a write processing unit that selects a shingled recording type for writing data in an overlapping manner to the plurality of tracks in an overlapping writing direction parallel to a radial direction of the disk, and causes the write head to write data to each of the bands; a determination unit for determining whether, in each of the bands, among all the recording sectors in which data is written, there is a recording sector with degraded quality, in which the quality of the recorded data is lower than a reference level; as well as The refresh processing unit, when determining that a target band including the quality-degraded recording sector exists among the plurality of bands, reads target data of a plurality of target recording sectors as refresh targets 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 smaller than the number of all recording sectors.

2. The magnetic disk device according to claim 1, In the target band, the plurality of target recording sectors are a plurality of recording sectors arranged in the overlap writing direction.

3. The magnetic disk device according to claim 1, The plurality of bands further include an adjacent band adjacent to the target band in the radial direction, The first track of the plurality of tracks of the adjacent band, which is located at the end closest to the target band, includes one or more recording sectors and remaining unused sectors in which valid data is not 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 overlap writing direction.

4. The magnetic disk device according to claim 3, The magnetic disk device further comprises: a counter that counts the number of writes to k whenever data is written to the adjacent band; and a recording unit for storing the accumulated number of write times; If the track located at the end closest to the adjacent band among the plurality of tracks of the target band is set as the second track, Then the judgment unit When it is determined that the cumulative number of write times is less than the write number threshold, it is determined that one or more recording sectors in the second track that are arranged in the radial direction with the one or more recording sectors of the first track do not meet the quality-degraded recording sectors. When it is determined that the cumulative number of write times is greater than a write times threshold, it is determined that the one or more recording sectors in the second track that are arranged in the radial direction with the one or more recording sectors of the first track respectively meet the quality-deteriorated recording sectors, The refresh processing unit resets the accumulated number of writing times in the recording unit when refreshing the plurality of target recording sectors.

5. The magnetic disk device according to claim 1, The magnetic disk device further comprises: A cache for storing received write instructions and read instructions; and an instruction execution unit that executes write instructions and read instructions recorded in the cache, When the determination unit determines that it is an idle period in which there are no unexecuted instructions in the cache, The refresh processing unit refreshes the plurality of target recording sectors during the idle period.

6. The magnetic disk device according to claim 1, If in the plurality of tracks of the object tape, The track to which data is first written in the shingled recording type is set as the second track. The last track to be written is the third track. A track different from the second track and including the quality-degraded recording sector is defined as the fourth track. In the target band, the plurality of target recording sectors are all recording sectors of a plurality of tracks from the fourth track to the third track in the overlap writing direction.

7. The magnetic disk device according to claim 1, If in the plurality of tracks of the object tape, The track to which data is first written in the shingled recording type is set as the second track. The last track to be written is the third track. A track different from the second track and including the quality-degraded recording sector is defined as the fourth track. In the target band, the plurality of target recording sectors are a plurality of recording sectors arranged in the overlap writing direction from the quality-deteriorated recording sector of the fourth track to the recording sector of the third track.

8. The magnetic disk device according to claim 1, The quality of data recorded in the recording sector of the tape is the bit error rate of the data, The bit error rate of the data recorded in the quality-deteriorated recording sector, which is the bit error rate of the data having a quality lower than the reference level, is higher than the reference value. The bit error rate of data having a quality higher than the reference level is lower than the reference value, The determination unit determines whether or not, in each band, among all the recording sectors in which data is written, there is a quality-deteriorated recording sector in which a bit error rate of recorded data is higher than the reference value.

9. The magnetic disk device according to claim 1, The magnetic disk device further comprises: a read head for reading data from the disk; a read processing unit that causes the read head to read data from the disk; and a detection unit that detects the number of times the same data on the disk is read by the read processing unit, The number of times data recorded in the quality-deteriorated recording sector is read, which is the number of times data having a quality lower than the reference level is read, is greater than the reference number of times; The number of times data having a quality higher than the reference level is read is less than the reference number, The determination unit determines whether or not, in each band, there is a quality-deteriorated recording sector in which the number of times recorded data is read is greater than the reference number of times, among all the recording sectors in which data is written.

10. The magnetic disk device according to claim 1, The write head is an energy-assisted recording magnetic head that performs energy-assisted recording.

Images