Magnetic disk device and recording format changing method

Abstract

A magnetic disk device and a method for changing a recording format that can improve reliability are provided. The magnetic disk device of this embodiment includes: a disk; a head having a read head for reading data from the disk, a write head for writing data to the disk, and an auxiliary element for generating energy that improves the writing performance of the write head; and a controller for selecting and executing a first recording format and a second recording format different from the first recording format, wherein either the first recording format or the second recording format is selected and executed based on the auxiliary effect of the auxiliary element.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-152013 (filing date: September 17, 2021), and the entire contents of the basic application are incorporated herein by reference. Technical Field

[0002] Embodiments of the present invention relate to a magnetic disk device and a method for changing a recording format. Background Art

[0003] To achieve higher recording densities and capacities in magnetic disk drives, technologies such as microwave-assisted magnetic recording (MAMR) and thermally-assisted magnetic recording (TAMR) have been developed. The MAMR technology uses a magnetic head with a recording pole (main pole) and a high-frequency oscillator. A high-frequency magnetic field, generated by energizing the high-frequency oscillator, is applied to the disk, thereby reducing the coercivity of the portion of the disk to which the high-frequency magnetic field is applied. The recording pole is excited by a recording current to generate a recording magnetic field. The TAMR technology uses a magnetic head with a light irradiation element that irradiates light onto the disk. The light is irradiated from the tip of the light irradiation element onto the disk, thereby locally heating the disk and reducing the coercivity of the heated portion of the disk.

[0004] There are also conventional magnetic recording (CMR) magnetic disk drives (or conventional recording) that write multiple tracks at intervals in the disk's radial direction, and shingled write magnetic recording (SMR) or shingled write recording (SWR) that overlaps multiple tracks in the disk's radial direction. In recent years, magnetic disk drives have been developed that can select between conventional and shingled recording modes. Summary of the Invention

[0005] An object of the embodiments of the present invention is to provide a magnetic disk device and a method for changing a recording format that can improve reliability.

[0006] The magnetic disk device involved in this embodiment comprises: a disk; a head, which has a read head for reading data from the disk, a write head for writing data to the disk, and an auxiliary element for generating energy to improve the writing performance of the write head; and a controller, which selects and executes a first recording type and a second recording type different from the first recording type, and selects and executes either the first recording type or the second recording type based on the auxiliary effect of the auxiliary element. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a block diagram showing the configuration of the magnetic disk device according to the first embodiment.

[0008] Figure 2 This is a schematic diagram showing an example of the arrangement of the head relative to the disk according to the first embodiment.

[0009] Figure 3 This is an enlarged cross-sectional view showing an example of the disk and the head according to the first embodiment.

[0010] Figure 4 This is a schematic diagram showing an example of normal recording processing.

[0011] Figure 5 This is a schematic diagram showing an example of tile recording processing.

[0012] Figure 6 This is a schematic diagram showing an example of changes in BER difference values ​​with respect to usage time in the magnetic disk device according to the first embodiment.

[0013] Figure 7 This is a schematic diagram showing an example of changes in the difference in resistance value of the auxiliary element of the magnetic disk device according to the first embodiment with respect to usage time.

[0014] Figure 8 This is a flowchart showing an example of a method for changing the recording type of a target head according to the life of an auxiliary element according to the first embodiment.

[0015] Figure 9 This is an enlarged cross-sectional view showing an example of a head according to Modification 1.

[0016] Figure 10 This is a flowchart showing an example of a method for changing the recording type of the target head according to the life of the auxiliary element according to the second modification.

[0017] Figure 11 This is a flowchart showing an example of a method for changing the recording mode of a predetermined head according to the life of an auxiliary element according to Modification 3.

[0018] Figure 12 This is a schematic diagram showing an example of a write processing method according to the second embodiment.

[0019] Figure 13 This is a schematic diagram showing an example of a write processing method according to Modification 4.

[0020] Figure 14 This is a schematic diagram showing an example of a write processing method according to the third embodiment.

[0021] Figure 15 This is a schematic diagram showing an example of a write processing method according to Modification 5.

[0022] Description of labels

[0023] 1 Magnetic disk device, 10 Magnetic disk, 10a User data area, 10b Media cache, 10c System area, 12 Spindle motor (SPM), 13 Arm, 14 Voice coil motor (VCM), 15 Head, 15 W write head, 15 R read head, 20 Driver IC, 30 Head amplifier IC, 40 Read / write (R / W) channel, 50 Hard disk controller (HDC), 60 Microprocessor (MPU), 70 Volatile memory, 80 Non-volatile memory, 90 Buffer memory, 100 Host system (Host), 130 System controller DETAILED DESCRIPTION

[0024] Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the accompanying drawings are merely examples and do not limit the scope of the invention.

[0025] (First embodiment)

[0026] Figure 1 This is a block diagram showing the configuration of the magnetic disk device 1 according to the first embodiment.

[0027] The magnetic disk drive 1 includes a head disk assembly (HDA) (described later), a driver IC 20, a head amplifier integrated circuit (hereinafter referred to as a head amplifier IC or preamplifier) ​​30, a volatile memory 70, a nonvolatile memory 80, a buffer memory (cache) 90, and a system controller 130, which is a single-chip integrated circuit. Furthermore, the magnetic disk drive 1 is connected to a host system (hereinafter referred to as a host) 100.

[0028] The HDA includes a magnetic disk (hereafter referred to as a disk) 10, a spindle motor (hereafter referred to as an SPM) 12, an arm 13 carrying a head 15, and a voice coil motor (hereafter referred to as a VCM) 14. The disk 10 is mounted on the SPM 12 and rotated by the SPM 12. The arm 13 and the VCM 14 constitute an actuator. Driven by the VCM 14, the actuator controls the movement of the head 15 mounted on the arm 13 to a predetermined position on the disk 10. Multiple disks 10 and multiple heads 15 are provided. Alternatively, only one disk 10 or one head 15 may be provided.

[0029] The disk 10 has a data-writable area divided into a user data area 10a accessible to the user, a media cache (sometimes also referred to as a media cache area or storage area) 10b that temporarily stores or records data (or commands) transmitted from a host, etc., before writing the data to a predetermined area within the user data area 10a, and a system area 10c where information required for system management is stored. Hereinafter, the direction from the inner periphery toward the outer periphery of the disk 10, or from the outer periphery toward the inner periphery, is referred to as the radial direction. Within the radial direction, the direction from the inner periphery toward the outer periphery is referred to as the outer direction (outer side), and the direction from the outer periphery toward the inner periphery is referred to as the inner direction (inner side). The direction perpendicular to the radial direction of the disk 10 is referred to as the circumferential direction. The circumferential direction corresponds to the direction along the circumference of the disk 10. The radial and circumferential directions are orthogonal to each other. Furthermore, a predetermined position in the radial direction of the disk 10 is sometimes referred to as a radial position, and a predetermined position in the circumferential direction of the disk 10 is sometimes referred to as a circumferential position. Radial positions and circumferential positions are sometimes referred to simply as positions. The disk 10 can be divided into multiple areas. For example, the disk 10 may be divided into regions (hereinafter sometimes referred to as zones) including a predetermined number of tracks in the radial direction. The zones may be divided into zones for each track in the radial direction.

[0030] In addition, a "track" refers to a recording area in a plurality of recording areas obtained by dividing the disk 10 in the radial direction, a recording area for one circle of a predetermined radial position of the disk 10, a predetermined recording area at a predetermined radial position of the disk 10, a recording area extended in the circumferential direction of the disk 10, a recording area corresponding to the path of the head 15 positioned at the predetermined radial position of the disk 10, a path of the head 15 positioned at the predetermined radial position of the disk 10, data written in a recording area in a plurality of recording areas obtained by dividing the disk 10 in the radial direction, and a recording area for one circle of a predetermined radial position of the disk 10. The term "data written in a predetermined area", "data written in a predetermined recording area at a predetermined radial position of the disk 10", "data written in a recording area extended in the circumferential direction of the disk 10", "data written in a recording area equivalent to the path of the head 15 positioned at a predetermined radial position of the disk 10", "data written along the path of the head 15 positioned at a predetermined radial position of the disk 10", "data extended in the circumferential direction of the disk 10", "data written in a predetermined track of the disk 10", "data for one week written in a predetermined track of the disk 10", "part of the data written in a predetermined track of the disk 10", and / or various other meanings are used. The term "sector" may be used to refer to one of a plurality of recording areas obtained by circumferentially dividing a predetermined track of the disk 10, one of a plurality of recording areas obtained by dividing a recording area extending circumferentially from a predetermined radial position of the disk 10, a predetermined recording area of ​​a predetermined track of the disk 10, a predetermined circumferential position of a predetermined track of the disk 10, a predetermined circumferential position (predetermined position) at a predetermined radial position of the disk 10, data written in one of a plurality of recording areas obtained by circumferentially dividing a predetermined track of the disk 10, data written in one of a plurality of recording areas obtained by circumferentially dividing a recording area extending circumferentially from a predetermined radial position of the disk 10, data written in a predetermined recording area of ​​a predetermined track of the disk 10, data written at a predetermined circumferential position of a predetermined track of the disk 10, data written at a predetermined circumferential position (predetermined position) at a predetermined radial position of the disk 10, data written in a predetermined sector, and / or various other meanings. The "radial width of a track" may also be referred to as "track width." The “path passing through the center position of the track width in a predetermined track” may also be referred to as the “track center.” The data written in the user data area 10 a and usable by the user may also be referred to as user data.

[0031] The head 15 faces the disk 10. For example, one head 15 faces one surface of the disk 10. The head 15 is mainly composed of a slider, and includes a write head 15W and a read head 15R attached to the slider. The write head 15W writes data to the disk 10. The read head 15R reads the data written to the disk 10. The "write head 15W" is sometimes simply referred to as the "head 15," the "read head 15R" as the "head 15," and the "write head 15W and read head 15R" as the "head 15." The "center of the head 15" is sometimes referred to as the "head 15," the "center of the write head 15W" as the "write head 15W," and the "center of the read head 15R" as the "read head 15R." The "center of the write head 15W" is sometimes simply referred to as the "head 15," and the "center of the read head 15R" as the "head 15." “Positioning the center of the head 15 at the center of the predetermined track” is sometimes expressed as “positioning the head 15 at the predetermined track”, “arranging the head 15 at the predetermined track”, or “locating the head 15 at the predetermined track”.

[0032] Figure 2 1 is a schematic diagram showing an example of the configuration of the head 15 relative to the disk 10 according to this embodiment. Figure 2 As shown, in the circumferential direction, the direction in which the disk 10 rotates is referred to as the rotation direction. Figure 2 In the example shown, the rotation direction is shown as counterclockwise, but the opposite direction (clockwise) may also be used.

[0033] exist Figure 2 In the example shown, disk 10 includes disks 10-0, ... Disk 10 has surfaces 10S (10S0, 10S1, ...). Disk 10-0 has a front surface 10S0 and a back surface 10S1 opposite to front surface 10S0. Front surface 10S0 includes a user data area 10a0, a media cache 10b0, and a system area 10c0. Back surface 10S1 includes a user data area 10a1, a media cache 10b1, and a system area 10c1.

[0034] The head 15 includes a plurality of heads 15. Figure 2 In the example shown, the head 15 includes a head 15-0, a head 15-1, ... The head 15 faces the surface 10S. The plurality of heads 15 face the surfaces 10S of the plurality of disks, respectively. Figure 2 In the example shown, head 15-0 faces surface 10S0. Head 15-0 writes data to surface 10S0 and reads data from surface 10S0. Head 15-1 faces back surface 10S1. Head 15-1 writes data to back surface 10S1 and reads data from back surface 10S1. Alternatively, three or more heads 15 and disk 10 may be provided.

[0035] Figure 3 FIG. 1 is an enlarged cross-sectional view showing an example of the disk 10 and the head 15 according to the present embodiment. Figure 3 In the embodiment, the rotation direction B of disk 10 (10-0, ...) coincides with the direction of air flow C. Hereinafter, the direction from head 15 (15-0, 15-1, ...) toward disk 10 is referred to as the downward direction or simply "downward," and the direction from disk 10 toward head 15 is referred to as the upward direction or simply "upward." When expressions such as "another layer above the predetermined layer" and "another layer below the predetermined layer" are used, the other layer may be in contact with the predetermined layer or located away from the predetermined layer.

[0036] exist Figure 3 In the example shown, disk 10 is stacked in this order: a substrate 111, a soft magnetic layer 112, a magnetic recording layer 113, and a protective film layer 114. Substrate 111 is formed of a disc-shaped non-magnetic material. Soft magnetic layer 112 is located on substrate 111. Soft magnetic layer 112 is formed from a material exhibiting soft magnetic properties. Magnetic recording layer 113 is located on soft magnetic layer 112. Magnetic recording layer 113 has magnetic anisotropy in a direction perpendicular to the surface of disk 10 (either the surface of magnetic recording layer 113 or the surface of protective film layer 114). Protective film layer 114 is located on magnetic recording layer 113.

[0037] exist Figure 3 In the illustrated example, the head 15 includes a slider 150. The slider 150 is formed, for example, from a sintered body of aluminum oxide and titanium carbide (AlTiC). The slider 150 has a disk-facing surface (air bearing surface (ABS)) 151 that faces the surface of the disk 10, such as the protective film layer 114, and a trailing end 153 located on the outflow side of the air flow C. Parts of the read head 15R and the write head 15W are exposed on the disk-facing surface 151.

[0038] The read head 15R consists of a magnetic film 161, a shield film 162, and a shield film 163. The magnetic film 161 is located between the shield films 162 and 163, generating a magnetoresistive effect. The shield film 162 is located on the trailing end 153 side relative to the magnetic film 161. The shield film 163 faces the shield film 162. The lower ends of the magnetic films 161, 162, and 163 are exposed on the disk-facing surface 151.

[0039] The write head 15W is disposed on the trailing end 153 side of the slider 150 relative to the read head 15R. The write head 15W includes a main magnetic pole 171, a trailing shield (write shield) 172, an insulator 173, a recording coil 180 arranged to flow magnetic flux to the main magnetic pole 171 and wound around a magnetic circuit including the main magnetic pole 171 and the write shield 172, and auxiliary elements such as a magnetic flux control unit (spin torque oscillator (STO)) 200.

[0040] The main magnetic pole 171 is formed of a soft magnetic material with a high saturation magnetic flux density. The main magnetic pole 171 generates a recording magnetic field in a direction perpendicular to the surface of the disk 10 in order to magnetize the magnetic recording layer 113 of the disk 10. In the example shown in the figure, the main magnetic pole 171 extends approximately perpendicularly to the disk facing surface 151. The lower surface of the front end portion 171a of the main magnetic pole 171 on the disk facing surface 151 side is exposed on the disk facing surface 151. The front end portion 171a of the main magnetic pole 171 narrows toward the disk facing surface 151 in a manner that becomes thinner at the front end, forming a columnar shape with a width narrower than other parts. The width of the front end portion 171a of the main magnetic pole 171 in the cross-track direction approximately corresponds to the track width of the predetermined track. The cross-track direction is, for example, a direction along the radial direction.

[0041] The write shield 172 is formed of a soft magnetic material having a high saturation magnetic flux density. The write shield 172 is provided to efficiently close the magnetic circuit via the soft magnetic layer 112 directly below the main magnetic pole 171. The write shield 172 is located on the trailing end 153 side relative to the main magnetic pole 171. The write shield 172 is connected to the main magnetic pole 171 via an insulator 173. The main magnetic pole 171 and the write shield 172 are electrically insulated and form a magnetic circuit. The write shield 172 is formed in a roughly L-shape and has a front end portion 172a on the disk-facing surface 151 side that is opposite to the front end portion 171a of the main magnetic pole 171 with a write gap therebetween. The lower surface of the front end portion 172a is exposed at the disk-facing surface 151 of the slider 150.

[0042] The recording coil 180 is provided so as to be wound around a magnetic circuit including the main magnetic pole 171 and the write shield 172 in order to allow magnetic flux to flow to the main magnetic pole 171. The recording coil 180 is provided, for example, between the main magnetic pole 171 and the write shield 172. By supplying a current of a predetermined magnitude (referred to as a write current or a recording current) to the recording coil 180, a recording magnetic field is excited in the main magnetic pole 171 and the write shield 172. As a result, the main magnetic pole 171 and the write shield 172 are magnetized. The magnetic flux flowing through the magnetized main magnetic pole 171 and the write shield 172 changes the magnetization direction of the recording bit of the magnetic recording layer 113 of the disk 10, thereby recording a magnetization pattern corresponding to the recording current on the disk 10.

[0043] An auxiliary element, such as a spin torque oscillator (STO) 200, is disposed between the front end 171a of the main magnetic pole 171 and the front end 172a of the write shield 172. In other words, the auxiliary element (STO) 200 is disposed in the write gap. For example, the auxiliary element (STO) 200 has the following structure: a base layer formed of a nonmagnetic conductive layer, a spin injection layer, an intermediate layer, an oscillation layer, and a gap layer formed of a nonmagnetic conductive layer are stacked in this order from the front end 171a side of the main magnetic pole 171 toward the front end 172a side of the write shield 172.

[0044] The auxiliary element (STO) 200 generates energy on the surface 10S (10S0, 10S1, ...) of the disk 10 to improve the writing performance of the write head 15W on the disk 10. When a predetermined energy (hereinafter sometimes referred to as element energy), such as a predetermined current (hereinafter referred to as bias current, drive current, or assist current) or a predetermined voltage (hereinafter referred to as bias voltage, drive voltage, or assist voltage) is applied to the auxiliary element (STO) 200, the gap magnetic field generated within the write gap causes the magnetization to rotate uniformly (spin precession), thereby generating a high-frequency magnetic field (microwave) with a frequency sufficiently higher than the frequency of the recording signal on the disk 10. The auxiliary element (STO) 200 applies a high-frequency magnetic field to the magnetic recording layer 113 of the disk 10, thereby reducing the coercive force of the magnetic recording layer 113. When the auxiliary element (STO) 200 generates a large precession of the spins, the magnetic permeability of the auxiliary element (STO) 200 becomes as low as that of air. Therefore, the magnetic flux from the main magnetic pole 171 is more likely to flow toward the disk 10 side than toward the write gap (auxiliary element 200). On the other hand, when the spin precession is not generated by the auxiliary element (STO) 200 or the spin precession is generated smaller than usual, the magnetic permeability of the auxiliary element (STO) 200 becomes higher than the magnetic permeability of air. Therefore, the magnetic flux from the main magnetic pole 171 is more likely to flow toward the write gap (auxiliary element 200) side than toward the disk 10. Hereinafter, the writing process of supplying element energy, such as a drive current (or sometimes also referred to as an auxiliary current) or a drive voltage (or sometimes also referred to as an auxiliary voltage), to an auxiliary element, such as STO200 to write data is sometimes referred to as auxiliary recording or high-frequency auxiliary recording. Hereinafter, the effect of assisting the writing process to the disk 10 is sometimes referred to as an auxiliary effect. In addition, "performing auxiliary recording" is sometimes referred to as simply "writing."

[0045] The driver IC 20 is connected to the system controller 130 (more specifically, the MPU 60 described later), the SPM 12 , and the VCM 14 , and controls driving of the SPM 12 and the VCM 14 under the control of the system controller 130 (more specifically, the MPU 60 described later).

[0046] The head amplifier IC (preamplifier) ​​30 includes a read amplifier and a write driver (not shown). The read amplifier amplifies the read signal read from the disk 10 and outputs it to the system controller 130 (more specifically, the read / write (R / W) channel 40 described later). The write driver includes, for example, a recording current control circuit 310 and an element energy control circuit 320. The recording current control circuit 310 is electrically connected to the recording coil 180 and supplies a recording current corresponding to the write data output from the R / W channel 40 to the recording coil 180. Hereinafter, the data written to the disk 10 may be referred to as write data, and the data read from the disk 10 may be referred to as read data. For example, the recording current control circuit 310 supplies a recording current to the recording coil 180 under the control of the system controller 130 (MPU 60). The element energy control circuit 320 is electrically connected to the auxiliary element, such as the spin-torque oscillator 200, and applies a predetermined element energy, such as a predetermined auxiliary current or a predetermined auxiliary voltage, to the spin-torque oscillator 200 under the control of the system controller 130, such as the MPU 60. Furthermore, the element energy control circuit 320 measures the resistance value of the auxiliary element, such as the spin-torque oscillator 200 (hereinafter sometimes referred to as the auxiliary element resistance value).

[0047] 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) or SDRAM (Synchronous Dynamic Random Access Memory).

[0048] The nonvolatile memory 80 is a semiconductor memory that records stored data even when power is cut off. The nonvolatile memory 80 is, for example, a NOR-type or NAND-type flash ROM (Flash Read Only Memory: FROM).

[0049] The buffer memory 90 is a semiconductor memory that temporarily records data exchanged between the magnetic disk drive 1 and the host computer 100. Alternatively, the buffer memory 90 may be integrated with the volatile memory 70. Examples of the buffer memory 90 include DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), or MRAM (Magnetoresistive Random Access Memory).

[0050] The system controller (controller) 130 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 130 includes a read / write (R / W) channel 40, a hard disk controller (HDC) 50, and a microprocessor (MPU) 60. The R / W channel 40, HDC 50, and MPU 60 are electrically connected to one another. The system controller 130 is electrically connected to, for example, the driver IC 20, the head amplifier IC 60, the volatile memory 70, the nonvolatile memory 80, the buffer memory 90, and the host system 100.

[0051] The R / W channel 40 performs signal processing for data transferred from the disk 10 to the host 100, such as read data, and for data transferred from the host 100, such as write data, in accordance with instructions from the MPU 60, described later. The R / W channel 40 is electrically connected to, for example, the head amplifier IC 30, the HDC 50, and the MPU 60. The R / W channel 40 includes circuitry or functionality for modulating write data. It also includes circuitry or functionality for measuring the signal quality of read data.

[0052] The HDC 50 controls data transfer between the host 100 and the R / W channel 40 according to instructions from the MPU 60 described later. The HDC 50 is electrically connected to the R / W channel 40, the MPU 60, the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90, for example.

[0053] The MPU 60 is a main controller that controls various components of the magnetic disk drive 1. The MPU 60 controls the VCM 14 via the driver IC 20 and performs positioning of the head 15. The MPU 60 controls the write operation to the disk 10 and selects the storage destination for data transferred from the host 100, such as write data. Furthermore, the MPU 60 controls the read operation from the disk 10 and controls the processing of data transferred from the disk 10 to the host 100, such as read data. Furthermore, the MPU 60 manages the area where data is recorded. 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 20, the R / W channel 40, and the HDC 50.

[0054] The MPU 60 includes an energy control unit 610, a resistance value measurement unit 620, a read / write control unit 630, and a life management unit 640. The MPU 60 executes the processing of each unit, such as the energy control unit 610, the resistance value measurement unit 620, the read / write control unit 630, and the life management unit 640, in firmware. Alternatively, the MPU 60 may include each unit, such as the energy control unit 610, the resistance value measurement unit 620, the read / write control unit 630, and the life management unit 640, as a circuit.

[0055] The energy control unit 610 controls (or adjusts) the energy supplied to the head 15. The energy control unit 610 controls (or adjusts) the recording current supplied (or applied) to the recording coil 180 and the element energy supplied (or applied) to the auxiliary element.

[0056] The energy control unit 610 controls (or adjusts) the energy supplied (or applied) to the recording coil 180 via the recording current control circuit 310, such as the recording current or the recording voltage. The energy control unit 610 controls (or adjusts) the energy supplied (or applied) via the recording current control circuit 310 to the plurality of recording coils 180 mounted on the plurality of heads 15, such as the head 15-0, the head 15-1, etc., such as the recording current or the recording voltage.

[0057] The energy control unit 610 controls (or adjusts) the element energy, such as the auxiliary current or auxiliary voltage, supplied (or applied) to the auxiliary element, such as the STO 200, via the element energy control circuit 320. The energy control unit 610 controls (or adjusts) the element energy, such as the auxiliary current or auxiliary voltage, supplied (or applied) to the plurality of auxiliary elements, such as the STO 200, mounted on the plurality of heads 15, such as the head 15-0, the head 15-1, ..., via the element energy control circuit 320.

[0058] The resistance measuring unit 620 measures the resistance of each component of the head 15. The resistance measuring unit 620 measures the resistance of auxiliary components, such as STO 200. The resistance measuring unit 620 measures the resistance of auxiliary components, such as STO 200, via the component energy control circuit 320 of the head amplifier IC 30. The auxiliary component resistance increases, for example, as the auxiliary component 200 degrades. In other words, the auxiliary component resistance increases, for example, as the life of the auxiliary component 200 shortens. In other words, the auxiliary component resistance increases, for example, as the auxiliary effect of the auxiliary component 200 decreases. The resistance measuring unit 620 measures, via the component energy control circuit 320, the resistance of multiple auxiliary components corresponding to the multiple auxiliary components, such as STO 200, mounted on the multiple heads 15, such as head 15-0, head 15-1, etc.

[0059] The read / write control unit 630 controls the writing and reading of data according to commands from the host 100 or the like. When the read / write control unit 630 receives a command from the host 100 or the like, it performs a write process to write data to a predetermined area. When the read / write control unit 630 receives a command from the host 100 or the like, it performs a read process to read data from a predetermined area. The read / write control unit 630 controls the VCM 14 via the driver IC 20 to position the head 15 at the target position on the disk 10 and perform a write process or a read process. Hereinafter, the term "access" may also be used to include the meanings of "recording or writing data (or writing process) to a predetermined area", "reading or reading data (or reading process) from a predetermined area", and "moving the head 15 or the like to a predetermined area".

[0060] The read / write control unit 630 performs write processing using, for example, conventional magnetic recording (CMR) technology. This conventional recording technology involves writing data or randomly writing data to other tracks (hereinafter sometimes referred to as adjacent tracks) or other sectors (hereinafter sometimes referred to as adjacent sectors) adjacent to a predetermined track or sector, separated by a predetermined interval (gap) in the radial direction. Here, "adjacent" encompasses data, objects, areas, and spaces that are arranged in contact with each other, but also encompasses data, objects, areas, and spaces that are arranged at predetermined intervals. "Adjacent tracks" include "tracks adjacent to a predetermined track in the outer direction," "tracks adjacent to a predetermined track in the inner direction," and "multiple tracks adjacent to a predetermined track in both the outer and inner directions." "Adjacent sectors" include "sectors adjacent to a predetermined sector in the outer direction," "sectors adjacent to a predetermined sector in the inner direction," and "multiple sectors adjacent to a predetermined sector in both the outer and inner directions." Hereinafter, "writing data in a normal recording mode" may be referred to as "performing normal recording," "performing normal recording processing," or simply "writing." Hereinafter, "a track on which normal recording has been performed" may be referred to as a "CMR track."

[0061] In addition, the read / write control unit 630 performs a write process in a shingled recording (Shingled write Magnetic Recording: SMR, or Shingled Write Recording: SWR) format, which is a format in which, when writing to multiple tracks sequentially, overlapping writing of the track to be written next is performed on a portion in the radial direction of the previously written track. Hereinafter, "writing data in a shingled recording format" may sometimes be referred to as "shingled recording" or "performing a shingled recording process," or simply as "writing." Hereinafter, "tracks on which shingled recording has been performed" may sometimes be referred to as "SMR tracks." When performing shingled recording on the user data area 10a, the read / write control unit 630 temporarily writes data transferred from the host 100, etc. to the media cache 10b, reads the data temporarily written to the media cache 10b, and writes the data read from the media cache 10b to the user data area 10a.

[0062] The read / write control unit 630 performs normal recording processing or performs shingle recording processing according to commands from the host 100. In other words, the read / write control unit 630 selectively performs normal recording processing and shingle recording processing according to commands from the host 100. In addition, the read / write control unit 630 can be configured to perform only normal recording processing or only shingle recording processing. For example, the read / write control unit 630 can selectively perform normal recording processing or shingle recording processing on multiple heads 15, such as head 15-0, head 15-1, etc., according to commands from the host 100. In addition, in the magnetic disk device 1, there are host-managed magnetic disk devices in which the user can set in detail the areas for performing normal recording processing and shingle recording processing, and drive-managed magnetic disk devices in which the user cannot set the areas for performing normal recording processing and shingle recording processing.

[0063] Figure 4 This is a diagram showing an example of normal recording processing. Figure 4 The direction of travel is shown in . Sometimes the direction in which the head 15 sequentially writes and reads data to and from the disk 10 in the circumferential direction, that is, the direction in which the head 15 travels relative to the disk 10 in the circumferential direction, is also referred to as the direction of travel. For example, the direction of travel is the direction opposite to the direction of rotation of the disk 10. In addition, the direction of travel may also be the same direction as the direction of rotation of the disk 10. Figure 4 The CMR tracks CTR1, CTR2, and CTR3 are shown in FIG. Figure 4 For example, the track widths of CMR tracks CTR1, CTR2, and CTR3 are the same. In addition, the track widths of CMR tracks CTR1 to CTR3 may be different. The terms "same," "identical," "consistent," and "equivalent" include the meaning of being completely identical, but also include the meaning of being different to the extent that they can be considered to be substantially the same. Figure 4 , the track center CTC1 of the CMR track CTR1, the track center CTC2 of the CMR track CTR2, and the track center CTC3 of the CMR track CTR3 are shown. Figure 4In the example shown, CMR tracks CTR1 and CTR2 are written with a track pitch CTP1. CMR tracks CTR2 and CTR3 are written with a track pitch CTP2. The track center CTC1 of CMR track CTR1 and the track center CTC2 of CMR track CTR2 are separated by the track pitch CTP1. The track center CTC2 of CMR track CTR2 and the track center CTC3 of track CTR3 are separated by the track pitch CTP2. The track pitches CTP1 and CTP2 may be different or the same. Hereinafter, the track pitch when writing to the tracks will sometimes be referred to as the recording pitch. CMR track CTR1 and CMR track CTR2 are separated by a gap GP1. CMR track CTR2 and CMR track CTR3 are separated by a gap GP2. The gaps GP1 and GP2 may be different or the same. In Figure 4 In the figure, for the sake of convenience, each track is shown as a rectangular shape extending in the circumferential direction with a predetermined track width, but in reality it is curved along the circumferential direction. In addition, each track can also be a wave shape that varies in the radial direction while extending in the circumferential direction.

[0064] exist Figure 4 In the illustrated example, the read / write control unit 630 positions the head 15 at the track center CTC1 in a predetermined area of ​​the disk 10, such as the user data area 10a, and performs normal recording on the CMR track CTR1 or a predetermined sector of the CMR track CTR1. The read / write control unit 630 positions the head 15 at the track center CTC2, which is located inwardly from the track center CTC1 of the CMR track CTR1 by a recording pitch CTP1, and performs normal recording on the CMR track CTR2 or a predetermined sector of the CMR track CTR2 in the user data area 10a. The read / write control unit 630 positions the head 15 at the track center CTC3, which is located inwardly from the track center CTC2 of the CMR track CTR2 by a recording pitch CTP2, and performs normal recording on the CMR track CTR3 or a predetermined sector of the CMR track CTR3 in the user data area 10a. The read / write control unit 630 can normally record the CMR tracks CTR1, CTR2, and CTR3 sequentially in a predetermined area of ​​the disk 10, such as the user data area 10a, or can randomly record the predetermined sectors of the CMR track CTR1, the predetermined sectors of the CMR track CTR2, and the predetermined sectors of the CMR track CTR3.

[0065] Figure 5 is a diagram showing an example of tile recording processing. Figure 5 The forward direction is shown in . Sometimes the direction of continuously recording multiple tracks in the radial direction, that is, the direction of overlapping the track to be written next with the track written previously in the radial direction is also called the forward direction. Figure 5 In the figure, the inner direction in the radial direction is taken as the forward direction, but the outer direction in the radial direction can also be taken as the forward direction. Figure 5 , multiple SMR tracks STR1, STR2, and STR3 are shown in which overlapping writing is continuously performed along one direction in the radial direction. Hereinafter, in tile recording, the area where data is written by the write head 15W is sometimes referred to as a write track, and the remaining area other than the area where overlapping writing of other write tracks is performed in the predetermined track is referred to as a read track. Figure 5 The track center STC1 of the SMR track STR1 without overlapping writing of other SMR tracks, the track center STC2 of the SMR track STR2 without overlapping writing of other SMR tracks, and the track center STC3 of the SMR track STR3 without overlapping writing of other SMR tracks are shown in FIG. Figure 5 In the example shown, SMR tracks STR1 and STR2 are written at a track pitch (recording pitch) STP1. SMR tracks STR2 and STR3 are written at a track pitch (recording pitch) STP2. The track center STC1 of the SMR track (or write track) STR1 and the track center STC2 of the SMR track (or write track) STR2 are spaced apart by the recording pitch STP1. The track center STC2 of the SMR track STR2 and the track center STC3 of the SMR track STR3 are spaced apart by the recording pitch STP2. The recording pitches STP1 and STP2 may be different or the same. Figure 5 In the SMR track STR1, the width in the radial direction of the area (read track) where overlapping writing of the SMR track STR2 is not performed is the same as the width in the radial direction of the area (read track) where overlapping writing of the SMR track STR3 is not performed in the SMR track STR2. In addition, the width in the radial direction of the area (read track) where overlapping writing of the SMR track STR2 is not performed in the SMR track STR1 may be different from the width in the radial direction of the area (read track) where overlapping writing of the SMR track STR3 is not performed in the SMR track STR2. Figure 5 In the figure, for the sake of convenience, each track is shown as a rectangular shape extending in the circumferential direction with a predetermined track width, but in reality, it is curved along the circumferential direction. In addition, each track can also be a wave shape that varies in the radial direction while extending in the circumferential direction. In addition, in Figure 5 In the example, three tracks are overlapped and written, but less than three or more than three tracks can also be overlapped and written.

[0066] exist Figure 5In the example shown, the read / write control unit 630 sequentially performs tile recording on the SMR tracks STR1 to STR3 in the inward direction. In addition, the read / write control unit 630 may also sequentially perform tile recording on the SMR tracks STR1 to STR3 in the outward direction. The read / write control unit 630 writes the SMR track STR2 at a recording pitch STP1 in the inward direction of the SMR track STR1, and performs overlapping writing of the track STR2 on a portion of the inward direction of the SMR track STR1. The read / write control unit 630 writes the SMR track STR3 at a recording pitch STP2 in the inward direction of the SMR track STR2, and performs overlapping writing of the SMR track STR3 on a portion of the inward direction of the SMR track STR2. In addition, the read / write control unit 630 may also write the SMR track STR2 at a recording pitch STP1 in the outward direction of the SMR track STR1, and performs overlapping writing of the track STR2 on a portion of the inward direction of the SMR track STR1. The read / write control unit 630 may also write the SMR track STR3 at the recording pitch STP2 in the outer direction of the SMR track STR2 and perform overlapping writing of the SMR track STR3 on a portion in the inner direction of the SMR track STR2.

[0067] The read / write control unit 630 supplies a recording current to the recording coil 180 to excite a recording magnetic field in the main magnetic pole 171 and the write shield 172, and supplies element energy, such as an auxiliary current or an auxiliary voltage, to the auxiliary element, such as the STO 200, to generate a high-frequency magnetic field, thereby writing (assisting recording) data to a predetermined area of ​​the disk 10. Alternatively, the read / write control unit 630 may supply a recording current to the recording coil 180 to excite a recording magnetic field in the main magnetic pole 171 and the write shield 172, and write data to the predetermined area of ​​the disk 10 without an auxiliary effect by not supplying element energy, such as an auxiliary current or an auxiliary voltage, to the auxiliary element, such as the STO 200. The read / write control unit 630 adjusts the recording current supplied to the multiple recording coils 180 respectively mounted on the multiple heads 15, such as head 15-0, head 15-1, ..., and adjusts the element energy, such as auxiliary current or auxiliary voltage, supplied to the auxiliary elements 200, such as STO200 respectively mounted on the multiple heads 15, such as head 15-0, head 15-1, ....

[0068] The read / write control unit 630 can selectively perform normal recording or tile recording in an auxiliary recording manner. Hereinafter, "performing normal recording in an auxiliary recording manner" is sometimes referred to as "auxiliary / normal recording". Sometimes, "performing auxiliary / normal recording" is also referred to as "auxiliary recording", "normal recording" or "writing". Sometimes, "performing normal recording without performing auxiliary recording" is also referred to as "normal recording" or "writing". In addition, "performing tile recording in an auxiliary recording manner" is sometimes referred to as "auxiliary / tile recording". Sometimes, "performing auxiliary / tile recording" is also referred to as "auxiliary recording", "tile recording" or "writing". Sometimes, "performing tile recording without performing auxiliary recording" is also referred to as "tile recording" or "writing". The read / write control unit 630 selectively performs auxiliary / normal recording or auxiliary / tile recording on a plurality of heads, such as head 15-0, head 15-1, ..., respectively.

[0069] The life management unit 640 manages the life of the head 15, for example, the auxiliary element 200. The life of the auxiliary element 200 can be, for example, the period until the auxiliary effect disappears, the period until the auxiliary effect decreases to a predetermined amount, the period until the auxiliary element 200 becomes unusable, the period until the durability of the auxiliary element 200 decreases to a predetermined level, or the period until the auxiliary element 200 degrades to a predetermined value. The life management unit 640 measures evaluation indicators corresponding to the life of the auxiliary element 200. The life management unit 640 measures multiple evaluation indicators corresponding to the life of the multiple auxiliary elements 200 mounted on the multiple heads 15, for example, heads 15-0, 15-1, ..., etc. The auxiliary element 200 may degrade depending on the number of times the magnetic disk device 1 or the auxiliary element 200 is used, and the duration of use of the magnetic disk device 1 or the auxiliary element 200. In other words, the life of the auxiliary element 200 shortens depending on the number of times the magnetic disk device 1 or the auxiliary element 200 is used, and the duration of use of the magnetic disk device 1 or the auxiliary element 200. Therefore, the evaluation index degrades according to the number of times the magnetic disk device 1 or the auxiliary element 200 is used and the usage time of the magnetic disk device 1 or the auxiliary element 200. The evaluation index includes, for example, the recording quality of data written by the predetermined head 15, such as the bit error rate (BER), and the auxiliary element resistance value of the auxiliary element 200 mounted on the predetermined head 15.

[0070] The life management unit 640 outputs a signal indicating a sign of reduced life or degradation of the target auxiliary element 200 (hereinafter sometimes also referred to as a degradation signal) when it determines that an evaluation index (hereinafter sometimes also referred to as a target evaluation index) corresponding to a predetermined auxiliary element (hereinafter sometimes also referred to as a target auxiliary element) 200 mounted on a predetermined head 15 (hereinafter sometimes also referred to as a target head) among the multiple heads 15 is greater than (or exceeds) a threshold value (hereinafter sometimes also referred to as an index threshold value or a target index threshold value) indicating a sign of reduced life or degradation of the target auxiliary element 200. For example, the life management unit 640 outputs a degradation signal when it determines that a BER (hereinafter sometimes also referred to as a target BER) corresponding to the target head 15 on which the target auxiliary element 200 is mounted is greater than (or exceeds) a threshold value corresponding to the BER (hereinafter sometimes referred to as a BER threshold value or a target BER threshold value) indicating a sign of reduced life or degradation of the target auxiliary element 200. For example, the life management unit 640 outputs a degradation signal when it determines that the auxiliary element resistance value corresponding to the target auxiliary element 200 (hereinafter sometimes referred to as the target auxiliary element resistance value) is greater than (or exceeds) a threshold value corresponding to the resistance value (hereinafter sometimes referred to as the resistance threshold value or the target resistance threshold value) indicating a sign of reduction in the life or degradation of the target auxiliary element 200. Evaluation thresholds include a BER threshold and a resistance threshold value.

[0071] The life management unit 640 outputs a signal urging the change of the recording type of the object head 15 corresponding to the object auxiliary element 200 (hereinafter sometimes referred to as a recording type change signal) based on the object evaluation index corresponding to the object auxiliary element 200. When the life management unit 640 determines that the object evaluation index corresponding to the object auxiliary element 200 is greater than the object index threshold (or exceeds the object index threshold), the life management unit 640 outputs a signal urging the change of the recording type of the object head 15 corresponding to the object auxiliary element 200 to the watt recording type (hereinafter sometimes referred to as a watt recording change signal). When the life management unit 640 determines that the evaluation index corresponding to the object auxiliary element 200 is below the index threshold, the life management unit 640 outputs a signal urging the change of the recording type of the object head 15 corresponding to the object auxiliary element 200 to the normal recording type (hereinafter sometimes referred to as a normal recording change signal). The recording type change signal includes a watt recording change signal and a normal recording change signal.

[0072] In the shingle recording process, compared to normal recording, random writes are not performed, and data that has degraded due to the effects of magnetic flux leakage from the head 15 during data writing (Adjacent Track Interference (ATI)) is rewritten less frequently (hereinafter also referred to as a refresh process). Therefore, compared to normal recording, the shingle recording process can reduce the frequency of head 15 usage. Consequently, the life of the auxiliary element 200 of the head 15 can be extended by performing the shingle recording process compared to normal recording.

[0073] For example, the life management unit 640 outputs a recording mode change signal corresponding to the target auxiliary element 200 based on the target BER corresponding to the target head 15 on which the target auxiliary element 200 is mounted. For example, if the life management unit 640 determines that the target BER corresponding to the target head 15 on which the target auxiliary element 200 is mounted is greater than (or exceeds) the target BER threshold, the life management unit 640 outputs a recording mode change signal corresponding to the target auxiliary element 200. For example, if the life management unit 640 determines that the target BER corresponding to the target head 15 on which the target auxiliary element 200 is mounted is less than the target BER threshold, the life management unit 640 outputs a normal recording mode change signal corresponding to the target auxiliary element 200.

[0074] For example, the life management unit 640 outputs a recording mode change signal corresponding to the target auxiliary element 200 based on the target auxiliary element resistance value corresponding to the target auxiliary element 200. For example, if the life management unit 640 determines that the target auxiliary element resistance value corresponding to the target auxiliary element 200 exceeds the target resistance threshold, the life management unit 640 outputs a wattage recording change signal. For example, if the life management unit 640 determines that the target auxiliary element resistance value corresponding to the target auxiliary element 200 is below the target resistance threshold, the life management unit 640 outputs a normal recording change signal.

[0075] The life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 via the read / write control unit 630 based on the target evaluation index corresponding to the target auxiliary element 200. If the life management unit 640 determines that the target evaluation index corresponding to the target auxiliary element 200 is greater than (or exceeds) an index threshold, the life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 from the normal recording mode to the watt recording mode via the read / write control unit 630, and performs watt recording processing using the target head 15 corresponding to the target auxiliary element 200. If the life management unit 640 determines that the target evaluation index corresponding to the target auxiliary element 200 is less than the target index threshold, the life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 from the watt recording mode to the normal recording mode via the read / write control unit 630, and performs normal recording processing using the target head 15 corresponding to the target auxiliary element 200.

[0076] For example, the life management unit 640 changes the recording mode of the target header 15 corresponding to the target auxiliary element 200 via the read / write control unit 630 based on the BER corresponding to the target header 15 mounted on the target auxiliary element 200. For example, if the life management unit 640 determines that the target BER corresponding to the target header 15 mounted on the target auxiliary element 200 is greater than (or exceeds) the target BER threshold, the life management unit 640 changes the recording mode of the target header 15 corresponding to the target auxiliary element 200 from the normal recording mode to the watt recording mode via the read / write control unit 630, and performs the watt recording process using the target header 15 corresponding to the target auxiliary element 200. For example, if the life management unit 640 determines that the target BER corresponding to the target header 15 mounted on the target auxiliary element 200 is less than the target BER threshold, the life management unit 640 changes the recording mode of the target header 15 corresponding to the target auxiliary element 200 from the watt recording mode to the normal recording mode via the read / write control unit 630, and performs the normal recording process using the target header 15 corresponding to the target auxiliary element 200.

[0077] For example, the life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 via the read / write control unit 650 based on the resistance value of the target auxiliary element corresponding to the target auxiliary element 200. For example, if the life management unit 640 determines that the resistance value of the target auxiliary element corresponding to the target auxiliary element 200 is greater than (or exceeds) the target resistance threshold, the life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 from the normal recording mode to the watt recording mode via the read / write control unit 650, and performs the watt recording process using the target head 15 corresponding to the target auxiliary element 200. For example, if the life management unit 640 determines that the resistance value of the target auxiliary element corresponding to the target auxiliary element 200 is less than the target resistance threshold, the life management unit 640 changes the recording mode of the target head 15 corresponding to the target auxiliary element 200 from the watt recording mode to the normal recording mode via the read / write control unit 650, and performs the normal recording process using the target head 15 corresponding to the target auxiliary element 200.

[0078] Figure 6 FIG. 1 is a diagram showing an example of changes in the BER difference value of the magnetic disk device 1 according to the present embodiment with respect to the usage time. Figure 6 In the figure, the horizontal axis represents the usage time (or the number of times the disk device 1 (predetermined head 15 or predetermined auxiliary element 200) is used, and the vertical axis represents the difference value (hereinafter sometimes referred to as BER difference value) ΔBER between the BER at the start of use of the disk device 1 (predetermined head 15 or predetermined auxiliary element 200) corresponding to the predetermined head 15 of the disk device 1 and the current BER. Figure 6 On the vertical axis, the BER difference value increases as it moves toward the front end of the arrow, and decreases as it moves toward the opposite side of the front end of the arrow. Figure 6 The vertical axis shows the evaluation threshold, for example, the BER threshold ThB. Figure 6 On the horizontal axis, the usage time passes as it moves toward the front end of the arrow. Figure 6 The horizontal axis of shows the usage time T0 (or the number of times used) corresponding to the evaluation threshold, for example, the BER threshold ThB. Figure 6FIG. 1 shows a change in the BER difference value (ΔBER) relative to the usage time (or number of times) of the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) when normal recording is performed on the disk 10 (hereinafter sometimes referred to as a change in the BER difference value during normal recording) BL1, and a change in the BER difference value (ΔBER) relative to the usage time (or number of times) of the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) when watt recording is performed on the disk 10 (hereinafter sometimes referred to as a change in the BER difference value during watt recording) BL2. The change in the BER difference value BL1 during normal recording and the change in the BER difference value BL2 during watt recording include a point A corresponding to the BER threshold value ThB.

[0079] exist Figure 6 In the example shown, the change in the BER differential value BL2 during watt recording changes more gradually from point A than the change in the BER differential value BL1 during normal recording. That is, when the BER differential value corresponding to the predetermined head 15 exceeds the BER threshold value ThB, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the change in the BER differential value corresponding to the head 15 can be mitigated. When the BER differential value corresponding to the predetermined head 15 exceeds the BER threshold value ThB, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the life of the auxiliary element 200 mounted on the head 15 can be extended. Therefore, when the BER differential value corresponding to the predetermined head 15 exceeds the BER threshold value, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the life of the magnetic disk device 1 mounted on the head 15 can be extended.

[0080] Figure 7 FIG. 1 is a diagram showing an example of how the difference in resistance of the auxiliary element of the magnetic disk device 1 according to the present embodiment changes with time. Figure 7 In the figure, the horizontal axis represents the usage time (or the number of times the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) is used, and the vertical axis represents the difference (hereinafter sometimes referred to as the resistance difference) ΔR between the auxiliary element resistance value at the beginning of use of the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) corresponding to the predetermined auxiliary element 200 mounted on the predetermined head 15 of the magnetic disk device 1 and the current auxiliary element resistance value. Figure 7 On the vertical axis, the resistance difference value increases as it moves toward the front end of the arrow, and decreases as it moves toward the opposite side of the front end of the arrow. Figure 7 The vertical axis shows the evaluation threshold value, for example, the resistance threshold value ThR. Figure 7 On the horizontal axis, the usage time passes as it moves toward the front end of the arrow. Figure 7The horizontal axis shows the usage time T1 (or the number of times used) corresponding to the evaluation threshold value, for example, the resistance threshold value ThR. Figure 7 The diagram shows a change in the resistance differential value (ΔR) relative to the usage time (or number of times) of the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) when normal recording is performed on the disk 10 (hereinafter sometimes referred to as a change in the resistance differential value during normal recording) RL1, and a change in the resistance differential value (ΔR) relative to the usage time (or number of times) of the magnetic disk device 1 (predetermined head 15 or predetermined auxiliary element 200) when watt recording is performed on the disk 10 (hereinafter sometimes referred to as a change in the resistance differential value during watt recording) RL2. The change in the resistance differential value RL1 during normal recording and the change in the resistance differential value RL2 during watt recording include a point B corresponding to the resistance threshold value ThR.

[0081] exist Figure 7 In the example shown, the change in resistance differential value RL2 during watt recording changes more gradually from point B than the change in resistance differential value RL1 during normal recording. That is, when the resistance differential value corresponding to a predetermined auxiliary element 200 of a predetermined head 15 exceeds the resistance threshold ThR, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the change in resistance differential value corresponding to the auxiliary element 200 can be mitigated. When the resistance differential value corresponding to a predetermined auxiliary element 200 of a predetermined head 15 exceeds the resistance threshold ThR, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the life of the auxiliary element 200 mounted on the head 15 can be extended. Therefore, when the resistance differential value corresponding to a predetermined head 15 exceeds the resistance threshold ThR, by changing the recording mode of the head 15 from the normal recording mode to the watt recording mode, the life of the magnetic disk device 1 mounted on the head 15 can be extended.

[0082] Figure 8 This is a flowchart showing an example of a method for changing the recording mode of the target head 15 according to the life of the auxiliary element 200 according to the present embodiment.

[0083] The MPU 60 performs auxiliary / normal recording processing on a predetermined area of ​​the disk 10 using a target head 15 among the multiple heads 15 (B801). The MPU 60 determines whether the target evaluation index corresponding to the target head 15 is greater than or less than the target index threshold (B802). For example, the MPU 60 determines whether the BER (or BER difference value) corresponding to the target head 15 is greater than or less than the BER threshold. For example, the MPU 60 determines whether the auxiliary element resistance value corresponding to the target auxiliary element 200 mounted on the target head 15 is greater than or less than the resistance threshold.

[0084] If the target evaluation threshold is determined to be less than or equal to the target index threshold (B802: No), the MPU 60 terminates the process. For example, if the target BER (or BER difference) is determined to be less than or equal to the target BER threshold, the MPU 60 terminates the process. For example, if the target auxiliary element resistance value is determined to be less than or equal to the target resistance threshold, the MPU 60 terminates the process.

[0085] If the target evaluation threshold is determined to be greater than the target index threshold (B802: Yes), the MPU 60 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, performs auxiliary / watt recording processing with the target head 15 (B803), and terminates the process. For example, if the target BER (or BER difference value) is determined to be greater than the target BER threshold, the MPU 60 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, performs auxiliary / watt recording processing with the target head 15, and terminates the process. For example, if the target auxiliary element resistance value is determined to be greater than the target resistance threshold, the MPU 60 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, performs auxiliary / watt recording processing with the target head 15, and terminates the process.

[0086] According to this embodiment, the magnetic disk device 1 uses a target head 15 among the multiple heads 15 to perform auxiliary / normal recording processing on a predetermined area of ​​the magnetic disk 10. When it is determined that the target evaluation index corresponding to the target head 15 is greater than the target index threshold, the magnetic disk device 1 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, and performs the auxiliary / watt recording processing with the target head 15. For example, when it is determined that the target BER (or BER difference value) corresponding to the target head 15 is greater than the target BER threshold, the magnetic disk device 1 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, and performs the auxiliary / watt recording processing with the target head 15. For example, when it is determined that the resistance value of the target auxiliary element is greater than the target resistance threshold, the magnetic disk device 1 changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode, and performs the auxiliary / watt recording processing with the target head 15. Magnetic disk device 1 uses target head 15 among multiple heads 15 to change the recording mode of target head 15 from the normal recording mode to the shingle recording mode in a predetermined area of ​​disk 10. This allows target head 15 to perform auxiliary / shingle recording processing, thereby eliminating random writes and reducing the frequency of refresh processing. This reduces the frequency of use of target head 15. Consequently, magnetic disk device 1 can extend the life of target head 15. This means that the life of magnetic disk device 1 can be extended, thereby improving the reliability of magnetic disk device 1.

[0087] Next, magnetic disk devices according to modifications and other embodiments of the first embodiment will be described. In the modifications and other embodiments, the same reference numerals are given to the same parts as those in the first embodiment, and their detailed description will be omitted.

[0088] (Variation 1)

[0089] The magnetic disk device 1 according to the first modification is capable of writing data using a thermally assisted magnetic recording (TAMR) method, which is different from the magnetic disk device 1 according to the first embodiment.

[0090] Figure 9 This is an enlarged cross-sectional view showing an example of the head 15 according to Modification 1.

[0091] exist Figure 9 In the illustrated example, the slider 150 includes a write head 15W, a read head 15R, a light generating element (eg, a laser diode) 250 , a waveguide 255 , and a near-field light irradiation element (plasmon generator, nearfield transducer) 256 .

[0092] The light generating element 250 is a (laser) light source and is mounted on the top of the slider 150 or on the gimbal. The light generating element 250 supplies light to the waveguide 255 by receiving an electric current or voltage from the head amplifier IC 30. Alternatively, the light generating element 250 may be mounted elsewhere than on the slider 150 or the gimbal. For example, the light generating element 250 may be mounted outside the arm 13 and head 15. The waveguide 255 transmits the light generated by the light generating element 250 to the near-field light irradiation element 256.

[0093] The near-field light irradiation element 256 is disposed at the lower end of the slider 150 facing the disk 10. When writing data to the disk 10, the near-field light irradiation element 256 generates near-field light from the laser light propagating through the waveguide 255 and irradiates the disk 10 with the near-field light. The irradiated near-field light heats the recording layer of the disk 10, reducing the coercivity of the recording layer. The near-field light irradiation element 256 is composed of a metal component. Alternatively, a lens for focusing the light propagated from the light generating element 250 onto the disk 10 may be provided in place of the near-field light irradiation element 256. In this way, by irradiating the disk 10 with the near-field light generated by the near-field light irradiation element 256, the magnetic disk drive 1 can perform high-density magnetic recording on the disk 10, which is a high-coercivity medium. Hereinafter, the write process of supplying a predetermined voltage or current to the light generating element 250 to write data is sometimes referred to as assist recording or thermally assisted recording. In addition, structures used to perform thermally assisted recording, such as a light generating element (e.g., a laser diode) 250, a waveguide 255, and a near-field light irradiation element (plasmon generator, near field transducer) 256, are sometimes referred to as auxiliary elements 200.

[0094] The near-field light irradiation element 256 determines the track width (or recording width) written by the write head 15W through the irradiation range of the near-field light (or sometimes also referred to as the spot range, thermal distribution width). That is, the track width corresponds to the width of the irradiation range of the near-field light. For example, when the near-field light irradiation element 256 irradiates the irradiation range of the near-field light with a width smaller than the width of the write head 15W, the track width of the track written by the write head 15W may be smaller than the width of the write head 15W. In addition, when the near-field light irradiation element 256 irradiates the irradiation range of the near-field light with a width larger than the width of the write head 15W, the track width of the track written by the write head 15W may be larger than the width of the write head 15W. Therefore, when the shape of the near-field light irradiation element changes due to factors such as heat generated when irradiating the near-field light, the irradiation range of the near-field light will change, and accordingly, the track width of the track written by the write head 15W will change. For example, when the current (bias current, drive current or auxiliary current) or voltage (called bias voltage, drive voltage or auxiliary voltage) supplied to the light generating element 250 is increased, the intensity of the near-field light irradiated from the near-field light irradiation element 256 increases, the thermal assist effect may be improved, but the irradiation range also increases, and the track width may also increase.

[0095] According to Modification 1, the magnetic disk device 1 can write data using the heat-assisted magnetic recording (TAMR) method. Therefore, the magnetic disk device 1 can improve reliability.

[0096] (Variation 2)

[0097] The magnetic disk device 1 according to Modification 2 reduces the assist current (or assist voltage) corresponding to the target head 15 when the target head 15 performs the shingle recording process. This is different from the magnetic disk device 1 according to the aforementioned embodiment and Modification 1.

[0098] When the MPU60 determines that the object evaluation index corresponding to the object auxiliary element 200 mounted on the object head 15 is greater than the object index threshold (or exceeds the object index threshold) and the recording mode of the object head 15 is changed from the normal recording mode to the watt recording mode, the auxiliary current (hereinafter sometimes also referred to as the object auxiliary current) or the auxiliary voltage (hereinafter sometimes also referred to as the object auxiliary voltage) supplied to the object auxiliary element 200 is changed (or adjusted) to a smaller auxiliary current (hereinafter sometimes also referred to as the normal recording auxiliary current or the object normal recording auxiliary current) or the auxiliary voltage (hereinafter sometimes also referred to as the normal recording auxiliary voltage or the object normal recording auxiliary voltage) supplied to the object auxiliary element 200 when the watt recording process is performed than the auxiliary current (hereinafter sometimes also referred to as the normal recording auxiliary current or the object normal recording auxiliary current) or the auxiliary voltage (hereinafter sometimes also referred to as the normal recording auxiliary voltage or the object normal recording auxiliary voltage) supplied to the object auxiliary element 200 when the watt recording process is performed. At this time, MPU60 changes (or adjusts) the recording current (hereinafter sometimes also referred to as the object recording current) or the recording voltage (hereinafter sometimes also referred to as the object recording voltage) supplied to the recording coil 180 of the object head 15 to a recording current (hereinafter sometimes also referred to as the normal recording current or the object normal recording current) or the recording voltage (hereinafter sometimes also referred to as the normal recording voltage or the object normal recording voltage) supplied to the recording coil 180 of the object head 15 when performing the normal recording processing, which is larger than the recording current (hereinafter sometimes also referred to as the normal recording current or the object normal recording current) or the recording voltage (hereinafter sometimes also referred to as the normal recording voltage or the object normal recording voltage) supplied to the recording coil 180 of the object head 15 when performing the watt recording processing. The amount of change in the recording quality of the data written through the object head 15 when the object normal recording current (or object normal recording voltage) is changed to the object watt recording current (or object watt recording voltage) (hereinafter sometimes referred to as the amount of change in the recording quality when the normal recording current (or normal recording voltage) is changed to the watt recording current (or object watt recording voltage)) is equivalent to the amount of change in the recording quality of the data written through the object head 15 when the object normal recording auxiliary current (or object normal recording auxiliary voltage) is changed to the object watt recording auxiliary current (or object watt recording auxiliary voltage) (hereinafter sometimes referred to as the amount of change in the recording quality when the normal recording auxiliary current (or normal recording auxiliary voltage) is changed to the watt recording auxiliary current (or object watt recording auxiliary voltage)).

[0099] When the MPU60 changes the recording mode of the object head 15 corresponding to the object auxiliary element 200 from the normal recording mode to the watt recording mode, the object auxiliary current or the object auxiliary voltage supplied to the object auxiliary element 200 is reduced from the object normal recording auxiliary current or the object normal recording auxiliary voltage to the object watt recording auxiliary current or the object watt recording auxiliary voltage, and the object recording current or the object recording voltage supplied to the recording coil 180 of the object head 15 is increased from the object normal recording current or the object normal recording voltage to the object watt recording current or the object watt recording voltage, so as to compensate for the change in recording quality when data is written using the object head 15 due to the reduction from the object normal recording auxiliary current or the object normal recording auxiliary voltage to the object watt recording auxiliary current or the object watt recording auxiliary voltage.

[0100] Figure 10 This is a flowchart showing an example of a method for changing the recording mode of the target head 15 according to the life of the auxiliary element 200 according to the second modification.

[0101] The MPU 60 executes auxiliary / normal recording processing (B801) on a predetermined area of ​​the disk 10 using the target head 15 among the multiple heads 15. The MPU 60 determines whether the target evaluation index corresponding to the target head 15 is greater than or less than the target index threshold (B802).

[0102] When it is determined that the target evaluation threshold is equal to or less than the target index threshold ( B802 : NO), the MPU 60 ends the processing.

[0103] When determining that the target evaluation threshold is greater than the target index threshold ( B802 : YES), the MPU 60 changes the recording mode of the target head 15 from the normal recording mode to the tile recording mode and executes auxiliary / tile recording processing using the target head 15 ( B803 ).

[0104] The MPU 60 reduces the target auxiliary current (or target auxiliary voltage) supplied to the target auxiliary element 200 corresponding to the target head 15 from the target normal recording auxiliary current (or target normal recording auxiliary voltage) to the target watt recording auxiliary current (or target watt recording auxiliary voltage) (B1001). The MPU 60 increases the target recording current (or target recording voltage) supplied to the recording coil 180 of the target head 15 from the target normal recording current (or target normal recording voltage) to the target watt recording current (or target watt recording voltage) to compensate for the change in recording quality when data is written using the target head 15 due to the reduction from the target normal recording auxiliary current (or target normal recording auxiliary voltage) to the target watt recording auxiliary current (or target watt recording auxiliary voltage), and the processing ends.

[0105] According to Modification 2, when the recording mode of the target head 15 is changed from the normal recording mode to the watt recording mode, the magnetic disk drive 1 reduces the target auxiliary current or target auxiliary voltage supplied to the target auxiliary element 200 corresponding to the target head 15 from the target normal recording auxiliary current or target normal recording auxiliary voltage to the target watt recording auxiliary current or target watt recording auxiliary voltage. The magnetic disk drive 1 increases the target recording current or target recording voltage supplied to the recording coil 180 of the target head 15 from the target normal recording current or target normal recording voltage to the target watt recording current or target watt recording voltage, thereby compensating for the change in recording quality when data is written using the target head 15 caused by the reduction from the target normal recording auxiliary current or target normal recording auxiliary voltage to the target watt recording auxiliary current or target watt recording auxiliary voltage. Consequently, the magnetic disk drive 1 can extend the life of the target head 15. In other words, the life of the magnetic disk drive 1 can be extended. Consequently, the reliability of the magnetic disk drive 1 can be improved.

[0106] (Variation 3)

[0107] The magnetic disk device 1 involved in variant example 3, when performing tile recording processing using an object head 15 among multiple heads 15, uses other heads 15 different from the object head 15 among the multiple heads 15 to write to the medium cache 10b, and uses the object head 15 to write to the user data area 10a, which is different from the aforementioned embodiment and the magnetic disk device 1 involved in variant example 1.

[0108] When the MPU60 determines that the object evaluation index corresponding to the object auxiliary element 200 of the object head 15 mounted in the multiple heads exceeds the object index threshold and changes the recording mode of the object head 15 from the normal recording mode to the tile recording mode, it selects a head (hereinafter sometimes also referred to as other heads) 15 different from the object head 15 among the multiple heads 15 equipped with an auxiliary element (hereinafter sometimes also referred to as other auxiliary element) 200 having an evaluation index (hereinafter sometimes also referred to as other evaluation index) below the index threshold (hereinafter sometimes also referred to as other index threshold). The MPU 60 uses the selected other head 15 to temporarily write the data transmitted from the host 100, etc. to the medium cache (hereinafter sometimes also referred to as the other medium cache) 10b of the surface of the disk 10 (hereinafter sometimes also referred to as the other surface) to which the other head 15 is facing, uses the other head 15 to read the data written in the other medium cache 10b, and uses the object head 15 to auxiliary / record the data read from the other medium cache 10b by the other head 15 to the user data area (hereinafter sometimes also referred to as the object user data area) 10a of the surface of the disk 10 (hereinafter sometimes also referred to as the object surface) to which the object head 15 is facing.

[0109] For example, in Figure 2In the example, if the MPU 60 determines that the target evaluation index corresponding to the target auxiliary element 200 mounted on the target head 15-0 is greater than the target evaluation threshold (or exceeds the target evaluation threshold) and changes the recording mode of the target head 15-0 from the normal recording mode to the tile recording mode, the MPU 60 selects another head 15-1 mounted with another auxiliary element 200 whose other evaluation index is less than or equal to the other evaluation threshold. The MPU 60 uses the selected other head 15-1 to temporarily write data transmitted from the host 100, etc., to the media cache 10b1, uses the other head 15-1 to read the data written to the media cache 10b1, and uses the target head 15-0 to auxiliary / tile-record the data read from the media cache 10b1 by the other head 15-1 to the user data area 10a0.

[0110] Figure 11 This is a flowchart showing an example of a method for changing the recording mode of the head 15 in accordance with the life of the auxiliary element 200 according to the third modification.

[0111] The MPU 60 executes auxiliary / normal recording processing (B801) on a predetermined area of ​​the disk 10 using the target head 15 among the multiple heads 15. The MPU 60 determines whether the target evaluation index corresponding to the target head 15 is greater than or less than the target index threshold (B802).

[0112] When it is determined that the target evaluation threshold is equal to or less than the target index threshold ( B802 : NO), the MPU 60 ends the processing.

[0113] When determining that the target evaluation threshold is greater than the target index threshold ( B802 : YES), the MPU 60 changes the recording mode of the target head 15 from the normal recording mode to the tile recording mode and executes auxiliary / tile recording processing using the target head 15 ( B803 ).

[0114] The MPU 60 determines whether there is another head 15 whose other evaluation index is below the other index threshold value among the multiple heads 15, or whether there is no other head 15 (B1101). If it is determined that there is no other head 15 (B1101: No), the MPU 60 terminates the process. If it is determined that there is another head 15 (B1101: Yes), the MPU 60 selects another head 15 from the multiple heads 15 (B1102). The MPU 60 uses the selected other head 15 to write data transferred from the host 100, etc. to the other media cache 10b, and uses the other head 15 to read the written data from the other media cache 10b (B1103). The MPU 60 uses the target head 15 to supplement / record the data read from the other media cache 10b by the other head 15 in the target user data area 10a (B1104), and then terminates the process.

[0115] According to Modification 3, when the recording mode of the target head 15 is changed from the normal recording mode to the tile recording mode, the magnetic disk device 1 selects another head 15 from the plurality of heads 15. The magnetic disk device 1 uses the selected other head 15 to write data transmitted from the host 100 or the like to the other medium cache 10b, and uses the other head 15 to read the written data from the other medium cache 10b. The magnetic disk device 1 uses the target head 15 to assist / tile-record the data read from the other medium cache 10b by the other head 15 in the target user data area 10a. Therefore, the magnetic disk device 1 can extend the life of the target head 15. In other words, the life of the magnetic disk device 1 can be extended. Therefore, the reliability of the magnetic disk device 1 can be improved.

[0116] Furthermore, the configurations of the aforementioned embodiment and modified examples can be applied to a host managing a magnetic disk device and a drive managing a magnetic disk device.

[0117] (Second embodiment)

[0118] The write processing method of the magnetic disk device 1 according to the second embodiment is different from that of the magnetic disk devices 1 according to the first embodiment, Modification 1, Modification 2, and Modification 3 described above.

[0119] When the life management unit 640 writes predetermined data to the target recording area of ​​the disk 10 (hereinafter sometimes referred to as the target recording area) using the target head 15 via the read / write control unit 630, the life management unit 640 temporarily writes part or all of the data to a recording area different from the target recording area (hereinafter sometimes referred to as the other recording area) using the other heads 15, and writes the data written to the other recording area by the other heads 15 to the target recording area using the target head 15. Hereinafter, "temporarily writing predetermined data of a predetermined area to an area different from the predetermined area" will sometimes be referred to as "evacuation". When the life management unit 640 writes predetermined data to the target recording area of ​​the disk 10 using the target head 15 via the read / write control unit 630, the life management unit 640 evacuates part or all of the data to the other recording area using the other heads 15, and writes the data evacuated to the other recording area by the other heads 15 to the target recording area using the target head 15.

[0120] For example, before the life management unit 640 uses the object head 15 to write the data transmitted from the host 100 to the object user data area 10a of the object surface via the read / write control unit 630, the life management unit 640 temporarily writes the data to the other medium cache area 10b of the other surface using the other head 15, reads the data written to the other medium cache area 10b using the other head 15, and writes the data read from the other medium cache 10b using the other head 15 to the object user data area 10a of the object surface of the disk 10 using the object head 15. In other words, before the life management unit 640 writes the data transmitted from the host 100 to the object user data area 10a of the object surface using the object head 15 via the read / write control unit 630, it uses the other head 15 to retreat the data to the other medium cache area 10b of the other surface, uses the other head 15 to read the data retreated to the other medium cache area 10b, and uses the object head 15 to write the data read from the other medium cache 10b by the other head 15 to the object user data area 10a of the object surface of the disk 10.

[0121] For example, the life management unit 640 performs the following refresh processing via the read / write control unit 630: when the access frequency corresponding to the number of times the data written in the predetermined area (hereinafter sometimes also referred to as the rewrite area) of the object user data area 10a of the object surface, such as the predetermined track (hereinafter sometimes also referred to as the rewrite track) is accessed within a certain period of time is less than the predetermined number of times (hereinafter sometimes also referred to as the access frequency threshold), the data is temporarily written to the other medium cache area 10b of the other surface by the other head 15, the data written to the other medium cache area 10b is read by the other head 15, and the data read from the other medium cache 10b by the other head 15 is rewritten to the rewrite area of ​​the object user data area 10a of the object surface of the disk 10, such as the rewrite track, by the object head 15. In other words, the life management unit 640 performs the following refresh processing via the read / write control unit 630: when the access frequency of the data written to the rewrite area of ​​the object user data area 10a of the object surface is below the access frequency threshold, the data is retreated to the other medium cache area 10b of the other surface by other heads 15, the data retreated to the other medium cache area 10b is read by other heads 15, and the data read from the other medium cache 10b by other heads 15 is rewritten to the rewrite area of ​​the object user data area 10a of the object surface of the disk 10 by the object head 15.

[0122] Figure 12 This is a schematic diagram showing an example of a write processing method according to the second embodiment.

[0123] The MPU 60 executes a write process (B1201) and selects the other head 15 (B1202). The MPU 60 uses the other head 15 to evacuate the intended data to the other recording area (B1203), and uses the target head 15 to write the data evacuated to the other recording area by the other head 15 to the target recording area (B1204), thereby terminating the process. For example, before using the target head 15 to write data transferred from the host 100 to the target user data area 10a of the target surface, the MPU 60 uses the other head 15 to evacuate the data to the other media cache area 10b of the other surface. The other head 15 then reads the data evacuated to the other media cache area 10b, and uses the target head 15 to write the data read from the other media cache 10b by the other head 15 to the target user data area 10a of the target surface. In addition, for example, the MPU60 performs the following refresh processing via the read / write control unit 630: when the access frequency of the data written to the rewrite area of ​​the object user data area 10a of the object surface is below the access frequency threshold, the data is retreated to the other medium cache area 10b of the other surface by the other head 15, the data retreated to the other medium cache area 10b is read by the other head 15, and the data read from the other medium cache 10b by the other head 15 is rewritten to the rewrite area of ​​the object user data area 10a of the object surface of the disk 10 by the object head 15.

[0124] According to the second embodiment, the magnetic disk device 1 uses the other heads 15 to evacuate data to the target recording area by the target head 15 to the other recording area, and uses the target head 15 to write data that has been evacuated to the other recording area by the other heads 15 into the target recording area. This reduces the frequency of use of the target head 15. Consequently, the magnetic disk device 1 can extend the life of the target head 15. In other words, the life of the magnetic disk device 1 can be extended. Consequently, the reliability of the magnetic disk device 1 can be improved.

[0125] (Variation 4)

[0126] The write processing method of the magnetic disk device 1 according to the fourth modification is different from that of the magnetic disk device 1 described in the second embodiment.

[0127] When the target head 15 is used to write predetermined data to the target recording area of ​​the disk 10 via the read / write control unit 630 based on the target evaluation index corresponding to the target auxiliary element 200, the life management unit 640 temporarily writes part or all of the data to the other recording area using the other heads 15, and writes the data temporarily written to the other recording area by the other heads 15 back to the target recording area using the target head 15. In other words, when the target head 15 is used to write predetermined data to the target recording area of ​​the disk 10 via the read / write control unit 630 based on the target evaluation index corresponding to the target auxiliary element 200, the life management unit 640 evacuates part or all of the data to the other recording area using the other heads 15, and writes the data evacuated to the other recording area by the other heads 15 back to the target recording area using the target head 15.

[0128] If the life management unit 640 determines that the target evaluation index (the amount of change) corresponding to the target auxiliary element 200 is greater than (or exceeds) the target index (the amount of change in the target evaluation index) threshold, the life management unit 640 selects, via the read / write control unit 630, another head 15 equipped with another auxiliary element 200 whose other evaluation index (the amount of change) is less than the other index (the amount of change in the other evaluation index) threshold. For example, if the life management unit 640 determines that the target evaluation index (the amount of change) is greater than (or exceeds) the target index (the amount of change in the target evaluation index) threshold, the read / write control unit 630 selects, via the read / write control unit 630, another head 15 whose other evaluation index (the amount of change) is less than the target evaluation index (the amount of change). In other words, if the life management unit 640 determines that the target evaluation index (the amount of change) is greater than (or exceeds) the other evaluation index (the amount of change in the target evaluation index) threshold and greater than (or exceeds) the target index (the amount of change in the target evaluation index) threshold, the read / write control unit 630 selects, via the read / write control unit 630, another head 15 whose other evaluation index (the amount of change) is less than the target evaluation index (the amount of change in the target evaluation index). The life management unit 640, via the read / write control unit 630, uses the selected other head 15 to evacuate part or all of the predetermined data to the other recording area, and writes the data evacuated to the other recording area by the selected other head 15 into the target recording area using the target head 15. If the life management unit 640 determines that (the amount of change in) the target evaluation index corresponding to the target auxiliary element 200 is below the target index (the amount of change in the target evaluation index) threshold, the life management unit 640 uses the target head 15 to evacuate part or all of the predetermined data to the predetermined recording area via the read / write control unit 630, and writes the data evacuated to the predetermined recording area by the target head 15 into the target recording area using the target head 15.

[0129] When the life management unit 640 writes predetermined data to the target recording area of ​​the disk 10 using the target head 15 via the read / write control unit 630 based on the target BER corresponding to the target head 15 equipped with the target auxiliary element 200, it evacuates part or all of the data to the other recording area using the other head 15, and writes the data evacuated to the other recording area by the other head 15 back to the target recording area using the target head 15. When the life management unit 640 determines that the target BER (the amount of change) is greater than (or exceeds) the target BER (the amount of change) threshold, it selects, via the read / write control unit 630, another head 15 equipped with another auxiliary element 200 whose other BER (the amount of change) corresponding to the other head 15 is less than the BER (the amount of change) threshold corresponding to the other head 15 (hereinafter sometimes referred to as the other BER threshold). For example, if the life management unit 640 determines that the target BER (the amount of change) is greater than (or exceeds) the target BER (the amount of change) threshold, the life management unit 640 selects, via the read / write control unit 630, another head 15 whose BER (the amount of change) is smaller than the target BER (the amount of change). In other words, if the life management unit 640 determines that the target BER (the amount of change) is greater than (the amount of change) the other BER (the amount of change) and greater than (or exceeds) the target BER (the amount of change) threshold, the life management unit 640 selects, via the read / write control unit 630, another head 15 whose BER (the amount of change) is smaller than the target BER (the amount of change). The life management unit 640, via the read / write control unit 630, uses the selected other head 15 to save part or all of the predetermined data to another recording area, and uses the target head 15 to write the data saved to the other recording area by the selected other head 15 to the target recording area. When the life management unit 640 determines that the object BER (the amount of change) is below the threshold value of the object BER (the amount of change), it uses the object header 15 to retreat part or all of the predetermined data to the predetermined recording area via the read / write control unit 630, and writes the data retreated to the predetermined recording area using the object header 15 to the object recording area using the object header 15.

[0130] When the target head 15 writes predetermined data to the target recording area of ​​the disk 10 via the read / write control unit 630 based on the target auxiliary element resistance value corresponding to the target auxiliary element 200, the life management unit 640 evacuates part or all of the data to the other recording area using the other head 15, and writes the data evacuated to the other recording area by the other head 15 back to the target recording area using the target head 15. If the life management unit 640 determines that (the amount of change in) the target auxiliary element resistance value is greater than (or exceeds) a threshold value for target resistance (amount of change in target resistance value), the read / write control unit 630 selects another head 15 equipped with another auxiliary element 200 having an auxiliary element resistance value (hereinafter sometimes referred to as "other auxiliary element resistance value") corresponding to the other auxiliary element 200 mounted on the other head 15 that is less than or equal to the resistance threshold value corresponding to the other auxiliary element 200 (hereinafter sometimes referred to as "other resistance threshold") (threshold value for change in other resistance value). For example, if the life management unit 640 determines that the target auxiliary element resistance value (the amount of change) is greater than (or exceeds) the target resistance (the amount of change in the target resistance value) threshold value, the life management unit 640 selects, via the read / write control unit 630, another head 15 whose other auxiliary element resistance value (the amount of change) is smaller than the target resistance (the amount of change in the target resistance value) threshold value. In other words, if the life management unit 640 determines that the target auxiliary element resistance value (the amount of change) is greater than (the amount of change in the target resistance value) of the other auxiliary elements and greater than (or exceeds) the target resistance (the amount of change in the target resistance value) threshold value, the life management unit 640 selects, via the read / write control unit 630, another head 15 whose other auxiliary element resistance value (the amount of change) is smaller than (the amount of change in the target auxiliary element resistance value). The life management unit 640, via the read / write control unit 630, uses the selected other head 15 to save part or all of the predetermined data to another recording area, and uses the target head 15 to write the data saved to the other recording area by the selected other head 15 into the target recording area. When the life management unit 640 determines that the resistance value (the amount of change in the object resistance value) of the object auxiliary element is below the threshold value of the object resistance (the amount of change in the object resistance value), the life management unit 640 uses the object head 15 to retreat part or all of the predetermined data to the predetermined recording area via the read / write control unit 630, and writes the data retreated to the predetermined recording area by the object head 15 into the object recording area by the object head 15.

[0131] Figure 13 This is a schematic diagram showing an example of a write processing method according to Modification 4.

[0132] The MPU 60 performs a write process (B1201). The MPU 60 determines whether the target evaluation index (the amount of change) corresponding to the target auxiliary element 200 is greater than the target index (the amount of change in the target evaluation index) threshold value, or whether the target evaluation index (the amount of change in the target evaluation index) threshold value is less than the target index (the amount of change in the target evaluation index) threshold value (B1301). If it is determined that the target evaluation index (the amount of change in the target evaluation index) is less than the target index (the amount of change in the target evaluation index) threshold value (B1301: No), the MPU 60 ends the process. If it is determined that the target evaluation index (the amount of change in the target evaluation index) is greater than the target index (the amount of change in the target evaluation index) threshold value (B1301: Yes), the MPU 60 determines whether there are other heads 15 whose other evaluation index (the amount of change in the target evaluation index) is less than the other index (the amount of change in the other evaluation index) threshold value (B1302). If it is determined that there are no other heads 15 whose other evaluation index (the amount of change in the target evaluation index) is less than the other index (the amount of change in the other evaluation index) threshold value (B1302: No), the MPU 60 ends the process. If it is determined that there is another head 15 whose (amount of change in) the other evaluation index is less than or equal to the threshold value of the other index (amount of change in the other evaluation index) (B1302: Yes), the MPU 60 selects the other head 15 (B1202). The MPU 60 uses the other head 15 to save the predetermined data to the other recording area (B1203), and uses the target head 15 to write the data saved to the other recording area by the other head 15 to the target recording area (B1204), thereby terminating the process.

[0133] According to Modification 4, when the magnetic disk device 1 determines that (the amount of change in) the target evaluation index corresponding to the target auxiliary element 200 is greater than the threshold value of the target index (the amount of change in the target evaluation index), it selects another head 15 equipped with another auxiliary element 200 whose (the amount of change in) other evaluation index is less than the threshold value of the other index (the amount of change in the other evaluation index). The magnetic disk device 1 uses the selected other head 15 to evacuate the predetermined data to the other recording area, and uses the target head 15 to write the data evacuated to the other recording area by the selected other head 15 to the target recording area. Therefore, the magnetic disk device 1 can extend the life of the target head 15. In other words, the life of the magnetic disk device 1 can be extended. Therefore, the reliability of the magnetic disk device 1 can be improved.

[0134] (Third embodiment)

[0135] The write processing method of the magnetic disk device 1 according to the third embodiment is different from the magnetic disk devices 1 described in the first embodiment, the second embodiment, the first modification, the second modification, the third modification, and the fourth modification.

[0136] When the object head 15 is used to write the predetermined data into the object recording area via the read / write control unit 630, the life management unit 640 changes the recording type and writes the predetermined data into the object recording area using the object head 15, or writes the predetermined data into other recording areas using other heads 15.

[0137] For example, when the life management unit 640 uses the object head 15 to normally record the predetermined data to the object surface via the read / write control unit 630, the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the tile recording mode, and uses the object head 15 to tile record the predetermined data to the object recording area, or uses other heads 15 to normally record the predetermined data to other surfaces.

[0138] Figure 14 This is a schematic diagram showing an example of a write processing method according to the third embodiment.

[0139] The MPU 60 performs a write process on the target surface using the target header 15 (B1401) and determines whether to change the recording type of the target header 15 (B1402). For example, the MPU 60 performs a normal recording process on the target surface using the target header 15 and determines whether to change the recording type. For example, the MPU 60 performs a tile recording process on the target surface using the target header 15 and determines whether to change the recording type of the target header 15.

[0140] If the MPU 60 determines that the recording mode of the target head 15 is not to be changed (B1402: No), the MPU 60 terminates the process. If the MPU 60 determines that the recording mode of the target head 15 is to be changed (B1402: Yes), the MPU 60 writes using the target head 15 with the changed recording mode, or selects another head 15 and writes to another surface using the selected other head 15 (B1403). For example, if the MPU 60 determines that the recording mode is to be changed, the MPU 60 records to the target surface using the target head 15, or records to another surface using another head 15 as usual.

[0141] According to the third embodiment, when the target head 15 is writing to the target surface and the recording type is changed, the magnetic disk device 1 uses another head 15 to write to the other surface. This reduces the frequency of use of the target head 15. Consequently, the magnetic disk device 1 can extend the life of the target head 15. In other words, the life of the magnetic disk device 1 can be extended. Consequently, the reliability of the magnetic disk device 1 can be improved.

[0142] (Variant 5)

[0143] The write processing method of the magnetic disk device 1 according to the fifth modification is different from that of the magnetic disk device 1 described in the third embodiment.

[0144] When the life management unit 640 writes the predetermined data into the object recording area using the object head 15 via the read / write control unit 630 based on the object evaluation index corresponding to the object auxiliary element 200, the life management unit 640 changes the recording type of the object head 15, writes the predetermined data into the object recording area using the object head 15, or writes the predetermined data into other recording areas using other heads 15.

[0145] When the life management unit 640 uses the object head 15 to normally record the predetermined data on the object surface via the read / write control unit 630 based on the object evaluation index corresponding to the object auxiliary element 200, the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the tile recording mode, and uses the object head 15 to tile record the predetermined data to the object recording area, or uses other heads 15 to normally record it to other surfaces.

[0146] When the life management unit 640 determines that the object evaluation indicator (the amount of change in the object evaluation indicator) corresponding to the object auxiliary element 200 is greater than the threshold value of the object indicator (the amount of change in the object evaluation indicator) (or exceeds the threshold value), the life management unit 640 changes the recording type of the object head 15 when writing to the object recording area with the object head 15 via the read / write control unit 630, writes to the object recording area with the object head 15, or selects another head 15 of another auxiliary element 200 equipped with another evaluation indicator (the amount of change in the other evaluation indicator) that is below the threshold value of the other indicator (the amount of change in the other evaluation indicator), and writes to the other recording area with the selected other head 15. For example, if the life management unit 640 determines that (the amount of change in) the target evaluation index corresponding to the target auxiliary element 200 is greater than (or exceeds) the target index (the amount of change in the target evaluation index) threshold, the life management unit 640, via the read / write control unit 630, changes the recording type of the target head 15 when writing to the target recording area using the target head 15, writes to the target recording area using the target head 15, or selects another head 15 equipped with another auxiliary element 200 having another evaluation index (the amount of change in) smaller than (the amount of change in) the target index. In other words, if the life management unit 640 determines that (the amount of change in) the target evaluation index is greater than (the amount of change in) the other evaluation index and greater than (or exceeds) the target index (the amount of change in) the threshold, the life management unit 640, via the read / write control unit 630, changes the recording type of the target head 15 when writing to the target recording area using the target head 15, writes to the target recording area using the target head 15, or selects another head 15 having another evaluation index (the amount of change in) smaller than (the amount of change in) the target index. When the life management unit 640 determines that the object evaluation index (the amount of change in the object evaluation index) corresponding to the object auxiliary element 200 is below the threshold value of the object index (the amount of change in the object evaluation index), it writes to the object recording area using the object head 15 via the read / write control unit 630.

[0147] When the life management unit 640 determines that the object evaluation indicator (the amount of change in the object evaluation indicator) corresponding to the object auxiliary element 200 is greater than the threshold value of the object indicator (the amount of change in the object evaluation indicator) (or exceeds the threshold value), the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the tile recording mode when the object head 15 is used to normally record to the object recording area via the read / write control unit 630, and writes to the object recording area with the object head 15, or selects other heads 15 of other auxiliary elements 200 equipped with other evaluation indicators (the amount of change in other indicators) below the threshold value of other indicators (the amount of change in other evaluation indicators), and uses the selected other heads 15 to normally record to other recording areas. For example, when the life management unit 640 determines that the object evaluation indicator (the amount of change in the object evaluation indicator) corresponding to the object auxiliary element 200 is greater than the threshold value of the object indicator (the amount of change in the object evaluation indicator) (or exceeds the threshold value), the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the tile recording mode when the object head 15 is used to normally record in the object recording area, and uses the object head 15 to record in the object recording area, or selects other heads 15 equipped with other auxiliary elements 200 whose other evaluation indicators (the amount of change in the object evaluation indicator) are smaller than (the amount of change in) the object evaluation indicator. In other words, if the life management unit 640 determines that (the amount of change in) the target evaluation index is greater than (the amount of change in) other evaluation indexes and is greater than (or exceeds) the target index (the amount of change in) threshold value, the life management unit 640, through the read / write control unit 630, changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode when the target head 15 is normally recording in the target recording area, and performs watt recording in the target recording area using the target head 15, or selects another head 15 whose (the amount of change in) other evaluation indexes is smaller than (the amount of change in) the target evaluation index. If the life management unit 640 determines that (the amount of change in) the target evaluation index corresponding to the target auxiliary element 200 is less than the target index (the amount of change in) threshold value, the life management unit 640, through the read / write control unit 630, performs normal recording in the target recording area using the target head 15.

[0148] For example, when the life management unit 640 writes predetermined data into the object recording area using the object head 15 via the read / write control unit 630 based on the object BER corresponding to the object head 15 equipped with the object auxiliary element 200, the life management unit 640 changes the recording type of the object head 15, writes the predetermined data into the object recording area using the object head 15, or writes the predetermined data into other recording areas using other heads 15.

[0149] When the life management unit 640 uses the object head 15 to normally record the predetermined data on the object surface via the read / write control unit 630 based on the object BER corresponding to the object head 15 equipped with the object auxiliary element 200, the life management unit 640 changes the recording mode from the normal recording mode to the tile recording mode, and uses the object head 15 to tile-record the predetermined data on the object recording area, or uses other heads 15 to normally record the predetermined data on other surfaces.

[0150] For example, if the life management unit 640 determines that the target BER corresponding to the target head 15 equipped with the target auxiliary element 200 is greater than the target BER threshold (or exceeds the target BER threshold), the life management unit 640, via the read / write control unit 630, changes the recording type of the target head 15 when writing to the target recording area using the target head 15, and writes to the target recording area using the target head 15, or selects another head 15 equipped with another auxiliary element 200 having another BER below another BER threshold, and writes to the other recording area using the selected other head 15. For example, if the life management unit 640 determines that (the amount of change in) the target BER corresponding to the target auxiliary element 200 is greater than (or exceeds the target BER threshold), the life management unit 640, via the read / write control unit 630, changes the recording type of the target head 15 when writing to the target recording area using the target head 15, and writes to the target recording area using the target head 15, or selects another head 15 equipped with another auxiliary element 200 having another evaluation index smaller than the target index. In other words, if the life management unit 640 determines that the target BER (the amount of change) is greater than the other BERs (the amount of change) and is greater than (or exceeds) the target BER (the amount of change) threshold, the life management unit 640, via the read / write control unit 630, changes the recording format of the target header 15 when writing to the target recording area using the target header 15, and writes to the target recording area using the target header 15, or selects another header 15 having a BER smaller than the target BER. If the life management unit 640 determines that the target BER (the amount of change) is less than the target BER (the amount of change) threshold, the life management unit 640, via the read / write control unit 630, writes to the target recording area using the target header 15.

[0151] When the life management unit 640 determines that the object BER (amount of change) corresponding to the object head 15 equipped with the object auxiliary element 200 is greater than the threshold value of the object BER (amount of change) (or exceeds the threshold value), the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the watt recording mode when the object head 15 is normally used to record in the object recording area, and uses the object head 15 to record in the object recording area, or selects another head 15 equipped with another auxiliary element 200 whose BER (amount of change) is below the threshold value of the other BER (amount of change), and uses the selected other head 15 to normally record in the other recording area. For example, if the life management unit 640 determines that the target BER corresponding to the target auxiliary element 200 is greater than the target BER threshold (or exceeds the threshold), the life management unit 640, through the read / write control unit 630, changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode when the target head 15 is normally recording in the target recording area, and performs watt recording in the target recording area using the target head 15, or selects another head 15 equipped with another auxiliary element 200 having a target BER (amount of change) smaller than the target BER (amount of change). In other words, if the life management unit 640 determines that the target BER (amount of change) is greater than the other BER (amount of change) and greater than the target BER (amount of change) threshold (or exceeds the threshold), the life management unit 640, through the read / write control unit 630, changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode when the target head 15 is normally recording in the target recording area, and performs watt recording in the target recording area using the target head 15, or selects another head 15 having a BER (amount of change) smaller than the target BER (amount of change). When the life management unit 640 determines that the target BER (amount of change) corresponding to the target auxiliary element 200 is below the target BER (amount of change) threshold, it normally records the target recording area using the target head 15 via the read / write control unit 630.

[0152] For example, when the life management unit 640 writes predetermined data into the object recording area using the object head 15 via the read / write control unit 630 based on the resistance value of the object auxiliary element corresponding to the object auxiliary element 200, the life management unit 640 changes the recording type of the object head 15, writes the predetermined data into the object recording area using the object head 15, or writes to other recording areas using other heads 15.

[0153] When the predetermined data is normally recorded on the target surface using the target head 15 via the read / write control unit 630 according to the resistance value of the target auxiliary element corresponding to the target auxiliary element 200, the life management unit 640 changes the recording mode from the normal recording mode to the tile recording mode, and records the predetermined data on the target recording area using the target head 15, or normally records the predetermined data on other recording areas using other heads 15.

[0154] For example, when the life management unit 640 determines that the resistance value (the amount of change in the object auxiliary element) corresponding to the object auxiliary element 200 is greater than the threshold value of the object resistance (the amount of change in the object resistance value) (or exceeds the threshold value), the life management unit 640 changes the recording type of the object head 15 when writing to the object recording area with the object head 15 via the read / write control unit 630, writes to the object recording area with the object head 15, or selects other heads 15 equipped with other auxiliary elements 200 whose resistance values ​​(the amount of change in the object resistance value) of other auxiliary elements are below the threshold value of other object resistance (the amount of change in the object resistance value), and writes to other recording areas with the selected other heads 15. For example, when the life management unit 640 determines that the resistance value (the amount of change in the object auxiliary element) corresponding to the object auxiliary element 200 is greater than the threshold value of the object resistance (the amount of change in the object resistance value) (or exceeds the threshold value), the life management unit 640 changes the recording type of the object head 15 when writing to the object recording area with the object head 15 via the read / write control unit 630, writes to the object recording area with the object head 15, or selects other heads 15 equipped with other auxiliary elements 200 whose resistance values ​​(the amount of change in the object auxiliary element) are smaller than (the amount of change in the object auxiliary element) resistance value. In other words, if the life management unit 640 determines that the resistance value (amount of change) of the target auxiliary element is greater than the resistance values ​​(amount of change) of the other auxiliary elements and is greater than (or exceeds) the threshold value of the target resistance (amount of change in the target resistance value), the life management unit 640 changes the recording type of the target head 15 when writing to the target recording area using the target head 15, or selects another head 15 whose resistance value (amount of change) of the other auxiliary elements is smaller than (amount of change in the target auxiliary element). If the life management unit 640 determines that the resistance value (amount of change) of the target auxiliary element is less than the threshold value of the target resistance (amount of change in the target resistance value), the life management unit 640 writes to the target recording area using the target head 15 via the read / write control unit 630.

[0155] When the life management unit 640 determines that the resistance value (the amount of change in the object auxiliary element) corresponding to the object auxiliary element 200 is greater than the threshold value of the object resistance (the amount of change in the object resistance value) (or exceeds the threshold value), the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the watt recording mode when the object head 15 is used to normally record in the object recording area, and uses the object head 15 to record in the object recording area, or selects other heads 15 equipped with other auxiliary elements 200 whose resistance value (the amount of change in the object resistance value) is below the threshold value of the other resistance (the amount of change in the object resistance value), and uses the selected other heads 15 to normally record in other recording areas. For example, when the life management unit 640 determines that the resistance value (the amount of change in the object auxiliary element) corresponding to the object auxiliary element 200 is greater than (or exceeds) the threshold value of the object resistance (the amount of change in the object resistance value), the life management unit 640 changes the recording mode of the object head 15 from the normal recording mode to the watt recording mode when the object head 15 is used to normally record to the object recording area, and uses the object head 15 to record to the object recording area, or selects other heads 15 equipped with other auxiliary elements 200 whose resistance value (the amount of change in the object resistance value) is smaller than the threshold value of other resistance (the amount of change in the object resistance value). In other words, if the life management unit 640 determines that the resistance value (amount of change) of the target auxiliary element is greater than the resistance values ​​(amount of change) of the other auxiliary elements and is greater than (or exceeds) the threshold value of the target resistance (amount of change in the target resistance value), the life management unit 640, through the read / write control unit 630, changes the recording mode of the target head 15 from the normal recording mode to the watt recording mode when the target head 15 is normally recording in the target recording area, and performs watt recording in the target recording area using the target head 15, or selects another head 15 whose resistance value (amount of change) of the other auxiliary elements is smaller than (amount of change in the resistance value) of the target auxiliary element. If the life management unit 640 determines that the resistance value (amount of change) of the target auxiliary element corresponding to the target auxiliary element 200 is less than the threshold value of the target resistance (amount of change in the target resistance value), the life management unit 640, through the read / write control unit 630, performs normal recording in the target recording area using the target head 15.

[0156] Figure 15 This is a schematic diagram showing an example of a write processing method according to Modification 5.

[0157] The MPU 60 performs a write process on the target surface using the target header 15 (B1401), and determines whether the target evaluation index (the amount of change in the target evaluation index) corresponding to the target auxiliary element 200 is greater than the target index (the amount of change in the target evaluation index) threshold value, or whether the target index (the amount of change in the target evaluation index) threshold value is less than the target index (the amount of change in the target evaluation index) threshold value (B1501). If the target evaluation index is determined to be less than the target index threshold value (B1501: No), the MPU 60 terminates the process. If the target evaluation index (the amount of change in the target evaluation index) is determined to be greater than the target index (the amount of change in the target evaluation index) threshold value (B1301: Yes), the MPU 60 determines whether to change the recording format of the target header 15 (B1402).

[0158] If it is determined that the recording type of the target head 15 is not to be changed (B1402: No), the MPU 60 terminates the process. If it is determined that the recording type of the target head 15 is to be changed (B1402: Yes), the MPU 60 determines whether there are other heads 15 whose other evaluation indicators (the amount of change) are below the threshold value of the other indicators (the amount of change of the other evaluation indicators) (B1502). If it is determined that there are no other heads 15 whose other evaluation indicators (the amount of change) are below the threshold value of the other indicators (the amount of change of the other evaluation indicators) (B1302: No), the MPU 60 terminates the process. If it is determined that there are other heads 15 whose other evaluation indicators (the amount of change) are below the threshold value of the other indicators (the amount of change of the other evaluation indicators) (B1302: Yes), the MPU 60 writes using the target head whose recording type has been changed, or selects another head 15 and writes to another surface using the selected other head 15 (B1403).

[0159] According to variation 5, when the magnetic disk device 1 determines that the object evaluation index corresponding to the object auxiliary element 200 is greater than the object index threshold (or exceeds the object index threshold), when writing to the object recording area with the object head 15, the magnetic disk device 1 changes the recording type and writes to the object recording area with the object head 15, or selects another head 15 equipped with another auxiliary element 200 whose other evaluation index is below another index threshold, and writes to another recording area with the selected other head 15. The magnetic disk device 1 can suppress the frequency of use of the object head 15. Therefore, the magnetic disk device 1 can extend the life of the object head 15. In other words, the life of the magnetic disk device 1 can be extended. Therefore, the magnetic disk device 1 can improve reliability.

[0160] While several embodiments have been described above, these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments may be implemented in a variety of other ways, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and / or their variations are intended to be within the scope and spirit of the invention, and are also intended to be within the scope of the invention as set forth in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: plate; a head having a read head for reading data from the disk, a write head for writing data to the disk, and an auxiliary element for generating energy that improves writing performance of the write head; and a controller that selects and executes a first recording mode and a second recording mode different from the first recording mode, and selects and executes either the first recording mode or the second recording mode based on the assisting effect of the assisting element; The first recording mode is a normal recording mode in which tracks are written at intervals in the radial direction of the disk. The second recording mode is a tile recording mode in which tracks are written so as to overlap in the radial direction. The controller selects and executes either the first recording mode or the second recording mode based on an error rate corresponding to the head. The controller executes the second recording mode when it is determined that the error rate is greater than a first threshold value indicating a sign of degradation of the auxiliary element.

2. The magnetic disk device according to claim 1, When the controller determines that the error rate is greater than the first threshold value, the controller reduces the first current supplied to the auxiliary element and increases the second current supplied to the write head.

3. The magnetic disk device according to claim 1, The disk has a first surface including a first media cache and a first user data area, and a second surface different from the first surface including a second media cache and a second user data area. The head includes a first head for writing to the first surface and a second head for writing to the second surface. When the controller determines that the first error rate corresponding to the first head is greater than the first threshold, the controller temporarily writes the first data to the second media cache using the second head, and writes the first data read from the second media cache to the first user data area using the first head.

4. The magnetic disk device according to claim 1, The controller selects and executes either the first recording mode or the second recording mode according to the resistance value of the auxiliary element.

5. The magnetic disk device according to claim 4, The controller executes the second recording mode when it is determined that the resistance value is larger than a second threshold value indicating a sign of degradation of the auxiliary element.

6. The magnetic disk device according to claim 5, When the controller determines that the resistance value is greater than the second threshold value, the controller reduces the first current supplied to the auxiliary element and increases the second current supplied to the write head.

7. The magnetic disk device according to claim 5, The disk has a first surface including a first media cache and a first user data area, and a second surface different from the first surface including a second media cache and a second user data area. The head includes a first head for writing to the first surface and a second head for writing to the second surface. When the controller determines that the first resistance value corresponding to the first head is greater than the second threshold value, the controller temporarily writes the first data to the second media cache using the second head, and writes the first data read from the second media cache to the first user data area using the first head.

8. A method for changing a recording mode, applied to a magnetic disk device comprising a disk and a head, the head comprising a read head for reading data from the disk, a write head for writing data to the disk, and an auxiliary element for generating energy to improve the writing performance of the write head, the method comprising: selecting and executing a first recording format and a second recording format different from the first recording format; and According to the auxiliary effect of the auxiliary element, either the first recording mode or the second recording mode is selected and executed. The first recording mode is a normal recording mode in which tracks are written at intervals in the radial direction of the disk. The second recording mode is a tile recording mode in which tracks are written so as to overlap in the radial direction. selecting and executing either the first recording mode or the second recording mode based on an error rate corresponding to the header; The second recording pattern is executed when it is determined that the error rate is greater than a first threshold value indicating a sign of degradation of the auxiliary element.

9. A magnetic disk device comprising: a disk having a first side including a first media cache and a first user data area, and a second side different from the first side including a second media cache and a second user data area; a first head including a first read head for reading data from the first surface, a first write head for writing data to the first surface, and a first auxiliary element for generating energy to improve writing performance of the first write head; a second head including a second read head for reading data from the second surface, a second write head for writing data to the second surface, and a second auxiliary element for generating energy to improve writing performance of the second write head; as well as The controller temporarily writes the first data to the second side using the second head when the first data is written to the first side using the first head.

10. The magnetic disk device according to claim 9, A change in a first resistance value of the first auxiliary element is greater than a change in a second resistance value of the second auxiliary element.

11. The magnetic disk device according to claim 9, The amount of change in the first BER corresponding to the first header is greater than the amount of change in the second BER corresponding to the second header.

12. The magnetic disk device according to any one of claims 9 to 11, The controller executes a refresh process on a first track including the first data when the access frequency to the first data is equal to or less than a first threshold value.

13. The magnetic disk device according to any one of claims 9 to 11, When the controller writes the first data to the first user data area using the first head, the controller temporarily writes the first data to the second media cache using the second head.

14. The magnetic disk device according to any one of claims 9 to 11, When the controller writes the first data into the first user data area using the first head, the controller temporarily writes the first data into the second user data area using the second head.

15. A magnetic disk device comprising: a disk having a first side including a first media cache and a first user data area, and a second side different from the first side including a second media cache and a second user data area; a first head including a first read head for reading data from the first surface, a first write head for writing data to the first surface, and a first auxiliary element for generating energy to improve writing performance of the first write head; a second head including a second read head for reading data from the second surface, a second write head for writing data to the second surface, and a second auxiliary element for generating energy to improve writing performance of the second write head; as well as A controller that refreshes and writes data written to the first side using the first head and the tile recording mode to the second side using the second head and the normal recording mode, or refreshes and writes data written to the second side using the second head and the normal recording mode to the first side using the first head and the tile recording mode.

16. The magnetic disk device according to claim 15, A change in a first resistance value of the first auxiliary element is greater than a change in a second resistance value of the second auxiliary element.

17. The magnetic disk device according to claim 15, The amount of change in the first BER corresponding to the first header is greater than the amount of change in the second BER corresponding to the second header.

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