Method and magnetic disk apparatus

Abstract

To provide a method and a magnetic disk apparatus capable of improving recording quality.SOLUTION: A method includes acquisition, calculation, selection, and assignment. The acquisition is to acquire a result of quality inspection related to recording quality of a first plurality of sectors included in a first storage area of a magnetic disk. The calculation is to calculate, based on a set capacity of the first storage area and a set value of a recording density of the first storage area, a first number that is the number of sectors corresponding to a capacity obtained by subtracting a set capacity from an actual capacity of the first storage area. The selection is to select a second number of sectors of the first plurality of sectors based on the result. The assignment is to assign an address usable by a host to a group of a number of sectors corresponding to the set capacity not included in the second number of sectors of the first plurality of sectors.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present embodiment relates to a method and a magnetic disk drive. [Background technology]

[0002] Conventionally, a recording method known as SMR (Shingled Magnetic Recording) has been known for magnetic disk drives. SMR allows the track pitch to be narrower than the width of the write head, thereby improving recording density. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2016 / 0012849 Summary of the Invention [Problem to be solved by the invention]

[0004] With regard to magnetic disk drives, it is desired to improve not only the recording density but also the recording quality.

[0005] An object of one embodiment is to provide a method and a magnetic disk drive that can improve recording quality. [Means for solving the problem]

[0006] According to one embodiment, the method includes acquiring, calculating, selecting, and assigning. The acquiring step involves acquiring quality inspection results related to the recording quality of a first plurality of sectors included in a first storage area of ​​a magnetic disk included in a magnetic disk drive. The first storage area includes a first plurality of tracks to which data is written using a shingled magnetic recording (SMR) method. Each of the first plurality of tracks includes a different plurality of sectors from the first plurality of sectors. The calculating step involves calculating a first number, which is the number of sectors corresponding to a capacity obtained by subtracting the set capacity from the actual capacity of the first storage area, based on a set capacity and a set value of the recording density of the first storage area. The selecting step involves selecting a second number of sectors from the first plurality of sectors based on the result. The second number is greater than 0 and less than or equal to the first number. The assigning step involves assigning addresses usable by a host connected to the magnetic disk drive to a group of sectors from the first plurality of sectors that are not included in the second number of sectors and correspond to the set capacity. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a magnetic disk device according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a magnetic disk according to the first embodiment. [Figure 3] FIG. 3 is a diagram for explaining the SMR of the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the CMR according to the first embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a plurality of band areas provided on the magnetic disk of the first embodiment. [Figure 6] FIG. 6 is another diagram showing an example of a plurality of band areas provided on the magnetic disk of the first embodiment. [Figure 7] FIG. 7 is a diagram showing an example of track settings in each band area according to the first embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of the relationship between the actual capacity and the set capacity of the band area in the first embodiment. [Figure 9] FIG. 9 is a diagram for explaining areas to which LBAs are assigned by the magnetic disk device of the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining the inspection device of the first embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of the operation of quality inspection by the inspection device of the first embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of the operation of the magnetic disk device of the first embodiment. [Figure 13] FIG. 13 is a flowchart showing an example of the operation of quality inspection by the inspection device of the second embodiment. [Figure 14] FIG. 14 is a flowchart showing an example of the operation of the magnetic disk device of the second embodiment. [Figure 15] FIG. 15 is a diagram for explaining areas to which LBAs are assigned by the magnetic disk device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The method and magnetic disk drive according to the embodiments will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

[0009] (First embodiment) FIG. 1 is a diagram showing an example of the configuration of a magnetic disk device 1 according to the first embodiment.

[0010] The magnetic disk device 1 is connected to a host 2. The magnetic disk device 1 can receive access commands from the host 2. The access commands include write commands and read commands.

[0011] The magnetic disk device 1 includes a magnetic disk 11 having a magnetic layer formed on its surface. The magnetic disk device 1 accesses the magnetic disk 11 in response to an access command. Access includes writing data and reading data. The access command includes an address indicating a location in a logical address space that the magnetic disk device 1 provides to the host 2. The host 2 specifies the location to be accessed by the address included in the access command. The address is, for example, an LBA (Logical Block Address). In the following description, the address is assumed to be an LBA.

[0012] Data is written and read by a magnetic head 22. Specifically, in addition to a magnetic disk 11, the magnetic disk device 1 includes a spindle motor (SPM) 12, a ramp 13, an actuator arm 15, a voice coil motor (VCM) 16, a servo controller (SVC) 21, the magnetic head 22, a hard disk controller (HDC) 23, a preamplifier 24, a read / write channel (RWC) 25, a processor 26, a flash read only memory (FROM) 28, and a dynamic random access memory (DRAM) 29.

[0013] The magnetic disk 11 is rotated at a predetermined rotational speed by the SPM 12 attached coaxially.

[0014] 1 shows one magnetic disk 11. However, the magnetic disk device 1 may include multiple magnetic disks 11. When the magnetic disk device 1 includes multiple magnetic disks 11, the multiple magnetic disks 11 are rotated together by the SPM 12. In addition, a magnetic head 22 is provided for each recording surface of the multiple magnetic disks 11.

[0015] The SVC 21 is an integrated circuit that functions as a driver for driving the SPM 12 and the VCM 16. The processor 26 controls the rotation of the SPM 12 and the VCM 16 via the SVC 21.

[0016] The magnetic head 22 writes and reads data to and from the magnetic disk 11 using a write head 22w and a read head 22r provided thereto. The magnetic head 22 is attached to the tip of an actuator arm 15. The magnetic head 22 is moved in the radial direction of the magnetic disk 11 by a VCM 16 driven by an SVC 21. Note that a plurality of write heads 22w and / or read heads 22r provided to the magnetic head 22 may be provided for a single magnetic head 22.

[0017] When the magnetic disk 11 is stopped from rotating, the magnetic head 22 is moved onto the ramp 13. The ramp 13 is configured to hold the magnetic head 22 at a position spaced apart from the magnetic disk 11.

[0018] The preamplifier 24 is an integrated circuit that writes and reads data via the magnetic head 22. During a read operation, the preamplifier 24 amplifies and outputs a signal read from the magnetic disk 11 by the magnetic head 22, and supplies the signal to the RWC 25. During a write operation, the preamplifier 24 amplifies a signal corresponding to the data to be written, which is supplied from the RWC 25, and supplies the signal to the magnetic head 22.

[0019] The HDC 23 controls the transmission and reception of data to and from the host 2 via the I / F bus, and controls the DRAM 29 .

[0020] The DRAM 29 is used as a buffer for data sent and received between the host 2. For example, the DRAM 29 is used to temporarily store data to be written or data read from the magnetic disk 11.

[0021] The DRAM 29 is also used as an operating memory by the processor 26. The DRAM 29 is used as an area into which firmware programs are loaded. The DRAM 29 is also used as a buffer for data transfer between the host 2 and the magnetic disk 11.

[0022] The RWC 25 modulates the data to be written, which is supplied from the HDC 23, and supplies the modulated data to the preamplifier 24. The RWC 25 also performs demodulation, including error correction, on the signal read from the magnetic disk 11 and supplied from the preamplifier 24, and then outputs the signal to the HDC 23 as digital data.

[0023] The processor 26 is, for example, a CPU (Central Processing Unit). A FROM (Flash Read Only Memory) 28 and a DRAM 29 are connected to the processor 26.

[0024] The FROM 28 stores a firmware program and various setting information, etc. The firmware program may be stored on the magnetic disk 11.

[0025] The processor 26 performs overall control of the magnetic disk device 1 in accordance with a firmware program stored in the FROM 28 or the magnetic disk 11. For example, the processor 26 loads the firmware program from the FROM 28 or the magnetic disk 11 into the DRAM 29, and controls the SVC 21, the preamplifier 24, the RWC 25, the HDC 23, etc. in accordance with the firmware program loaded into the DRAM 29.

[0026] Note that some or all of the functions of the processor 26 may be realized by a hardware circuit such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0027] The HDC 23, RWC 25, and processor 26 are configured as a single integrated circuit, a System-On-a-Chip (SoC) 30. The SoC 30 may also include other elements (e.g., a FROM 28 or a DRAM 29). The SoC 30 is an example of a controller.

[0028] FIG. 2 is a diagram showing an example of the configuration of the magnetic disk 11 according to the first embodiment. Servo information is written to a magnetic layer formed on the surface of the magnetic disk 11 by, for example, a servo writer. The servo information may be written to the magnetic disk 11 by self-servo writing (SSW). The servo information includes sector / cylinder information, a burst pattern, and a postcode. The SoC 30 reads the servo information using the magnetic head 22 and performs a positioning operation based on the read servo information.

[0029] 2 shows radially arranged servo areas SV as an example of the arrangement of servo areas in which servo information is written. A plurality of concentric tracks TR are provided at a predetermined pitch in the radial direction of the magnetic disk 11. A large number of sectors are formed contiguously on each track TR. Data is written to and read from each sector by the magnetic head 22.

[0030] There are several types of recording methods, that is, methods for writing data to the magnetic disk 11. The recording methods include SMR (Shingled Magnetic Recording) and CMR (Conventional Magnetic Recording).

[0031] 3 is a diagram illustrating SMR according to the first embodiment. In SMR, data on a track TR (referred to as first data) is written, and then data on a track TR radially adjacent to the track TR (referred to as second data) is written. When writing the second data, the second data is written so that the second data overlaps a portion of the first data. In other words, according to SMR, data on one track TR of two tracks TR radially adjacent to each other on the magnetic disk 11 is written so that the data overlaps a portion of the data on the other track TR of the two tracks TR.

[0032] As an example, FIG. 3 illustrates three tracks TR: track TR#M-1, track TR#M, and track TR#M+1. Tracks TR#M-1 and TR#M are adjacent to each other. Tracks TR#M and TR#M+1 are adjacent to each other. In this example, data is written in the following order: data on track TR#M-1, data on track TR#M, and data on track TR#M+1. The data on track TR#M is written so that it partially overlaps the data on track TR#M-1 in the radial direction. The data on track TR#M+1 is written so that it partially overlaps the data on track TR#M in the radial direction. In other words, according to SMR, data on one track TR repeatedly overlaps with data on an adjacent track TR to which data has already been written.

[0033] With SMR, data is written using the above method, so the track pitch TP is narrower than the element width (WHw) of the write head 22w of the magnetic head 22. As a result, it is possible to set a high recording density.

[0034] However, with SMR, the track pitch TP is narrow, making it susceptible to adjacent track erasure (ATE). Therefore, in principle, data for multiple radially consecutive tracks TR is updated at once. The area where multiple tracks TR are located for which a batch update is performed is called a band area. Update can also be expressed as change or rewrite.

[0035] Furthermore, according to SMR, data on one track TR is written so as to overlap a portion of data on an adjacent track TR to which data has already been written. Therefore, data can only be written to multiple consecutive tracks TR in one direction, either from the inner side to the outer side or from the outer side to the inner side. The radial direction corresponding to the order in which data is written to multiple consecutive tracks TR in this radial direction is referred to as the SMR direction. The SMR direction may be common to all band areas or may be determined for each band area. Hereinafter, as an example, the SMR direction is assumed to be common to all band areas.

[0036] 4 is a diagram for explaining CMR according to the first embodiment. As shown in this diagram, according to CMR, data on each track TR is arranged so as not to overlap with data on a track TR adjacent in the radial direction. In other words, CMR is a method in which data on two tracks TR adjacent to each other in the radial direction of the magnetic disk 11 is written so as not to overlap with each other.

[0037] For example, Figure 4 shows three tracks TR: track TR#N-1, track TR#N, and track TR#N+1. Track TR#N-1 and track TR#N are spaced apart in the radial direction. Track TR#N and track TR#N+1 are spaced apart in the radial direction. In other words, tracks TR#N-1, track TR#N, and track TR#N+1 are arranged so that the data of two adjacent tracks TR do not overlap each other.

[0038] With CMR, the track pitch TP is equal to or larger than the element width (WHw) of the write head 22w, so data at any position can be updated, resulting in high random access performance.

[0039] 5 and 6 are diagrams showing examples of a plurality of band areas provided on the magnetic disk 11 of the first embodiment.

[0040] The recording surface 100 of the magnetic disk 11, i.e., the area where tracks TR can be arranged, is radially divided into multiple storage areas 110. The multiple storage areas 110 include one media cache area 120 and multiple band areas 130. Areas where writing is prohibited, called guard areas 140, are provided between the storage areas 110. Each guard area 140 consists of, for example, one or more tracks TR.

[0041] The storage area 110 provided on the outermost radial side of the recording surface is set as a media cache area 120. The media cache area 120 is a storage area used as a temporary storage location for data. Data is written to the media cache area 120 using, for example, CMR. Note that the location of the media cache area 120 is not limited to the outermost radial side. Two or more media cache areas 120 may be provided on the recording surface.

[0042] Two or more of the multiple storage areas 110 are set as band areas 130. Multiple tracks TR are provided in each band area 130. In each band area 130, data is written to all tracks TR using the SMR method. When writing data to each band area 130, writing data from the band area 130 that is the write destination to an adjacent band area 130 across a guard area 140 is prohibited.

[0043] An LBA is mapped to each band area 130. Therefore, each band area 130 is used as the final storage location for data (referred to as write data) requested to be written by the host 2.

[0044] As described above, the data stored in each band area 130 is updated in units of band areas 130. For example, write data sent from the host 2 is temporarily buffered in the DRAM 29. All data (referred to as band data) in the band area 130, which is the final storage location of the write data buffered in the DRAM 29, is transferred to, for example, the media cache area 120. Then, the band data is updated in the media cache area 120 using the write data buffered in the DRAM 29. The updated band data is then overwritten in the band area 130. Note that the method of updating in units of band areas 130 is not limited to this.

[0045] FIG. 7 is a diagram showing an example of setting of tracks TR in each band area 130 in the first embodiment.

[0046] 7, the band area 130 includes nine tracks TR, namely, tracks TR#K to TR#(K+8). According to the SMR direction set in this band area 130, data is written to track TR#K first. After track TR#K, data is written to tracks TR#(K+1), TR#(K+2), TR#(K+3), TR#(K+4), TR#(K+5), TR#(K+6), and TR#(K+7) in that order, with data being written to track TR#(K+8) last.

[0047] A track TR, such as track TR#K, onto which data is written first in the band area 130 is referred to as a head track TR. A track TR, such as track TR#(K+8), onto which data is written last in the band area 130 is referred to as an end track TR.

[0048] The leading track can be considered to be the track TR closest to one of the two radial ends of one band area 130, and the trailing track can be considered to be the track TR closest to the other of the two radial ends of the one band area 130.

[0049] According to SMR, data on one track TR is written so as to overlap a portion of data on an adjacent track TR to which data has already been written. Therefore, the track width W1 of all tracks TR except for track TR#(K+8), i.e., tracks TR#K to TR#(K+7), is narrower than the element width WHw of the write head 22w. In contrast, because track TR#(K+8) is the last track TR to be written to in the band area 130, the track width W2 of track TR#(K+8) is equal to the element width WHw of the write head 22w. In other words, the track width W2 of track TR#(K+8) is wider than the track width W1 of tracks TR#K to TR#(K+7).

[0050] The recording performance of each magnetic head 22 varies due to manufacturing variations. Furthermore, the data retention capacity of the recording surface of the magnetic disk 11 also varies. Therefore, the recording surface is divided into multiple zones in the radial direction, and a recording density is set for each combination of a zone and a magnetic head 22. The recording density of the magnetic disk 11 is defined as TPI (Track Per Inch) and BPI (Bit Per Inch). TPI is the arrangement density of the tracks TR, and BPI is the recording density along the tracks TR.

[0051] The larger the TPI, the narrower the track width W, and the worse the recording quality. Also, the larger the BPI, the worse the recording quality. The TPI and BPI are set so that the recording density is as high as possible under the constraint of maintaining the recording quality at a predetermined level or above.

[0052] Each band area 130 is included in one of the zones. In the band area 130 shown in FIG. 7, the track width W1 is determined according to the TPI set for the zone including that band area 130. However, the track width W2 of the last track TR, track TR#(K+8), is wider than the track width W1 of tracks TR#K to TR#(K+7). Therefore, the recording quality of track TR#(K+8) is higher than the recording quality of tracks TR#K to TR#(K+7).

[0053] 7 shows the write / read direction. The write / read direction is the direction in which data is written to or read from each track TR. The magnetic head 22 moves relative to the magnetic disk 11 as the magnetic disk 11 rotates. Therefore, the write / read direction is opposite to the rotation direction of the magnetic disk 11.

[0054] In a single track TR, writing / reading is performed sector by sector in the write / read direction. Therefore, a band start sector, which is the sector to be written first in the band area 130, and a band end sector, which is the sector to be written last in the band area 130, are determined. The band start sector is included in track TR#K, which is the first track TR. The band end sector is included in track TR#(K+8), which is the end track TR.

[0055] Generally, the storage capacity of each band area 130 is set based on the specifications required by the customer. When the magnetic disk device 1 is manufactured, the setting of each band area 130 is performed so that the storage capacity of each band area 130 is a set value (hereinafter referred to as set capacity) based on the specifications required by the customer. In reality, since each band area 130 is set in units of tracks TR, the actual storage capacity (hereinafter referred to as actual capacity) of each band area 130 may be slightly larger than the set capacity.

[0056] FIG. 8 is a diagram for explaining an example of the relationship between the actual capacity and the set capacity of the band area 130 in the first embodiment.

[0057] 8 shows band areas 130a and 130b arranged at different radial positions. The hatched areas 160 in band areas 130a and 130b indicate a group of sectors into which data of a set capacity is written without gaps starting from the band head sector of each band area 130. Area 150 is a group of surplus sectors, the number of which corresponds to the capacity obtained by subtracting the set capacity from the actual capacity of band area 130, generated in the last track TR. Area 150 is referred to as the surplus sector group 150. Each sector constituting surplus sector group 150 is referred to as a surplus sector.

[0058] The recording density (i.e., the pair of TPI and BPI) of the band area 130 may differ, for example, from zone to zone. Therefore, the size of the surplus sector group 150, i.e., the number of surplus sectors, may differ from band area 130. In the example shown in Fig. 8, the number of surplus sectors in band area 130a is greater than the number of surplus sectors in band area 130b.

[0059] The recording quality within one band area 130 is generally not uniform across all sectors, but may vary locally due to various factors. As described above, the end track TR has a wider track width W than the other tracks TR, and therefore has higher recording quality than the sectors of the other tracks TR.

[0060] Therefore, in the first embodiment, the magnetic disk device 1 prohibits the use of sectors with low recording quality. The magnetic disk device 1 does not assign LBAs to sectors with low recording quality, but instead assigns LBAs to surplus sectors in the end track TR, so that sectors with high recording quality in the end track TR can be used instead of sectors with low recording quality. This improves the recording quality of the band area 130 as a whole.

[0061] 9 is a diagram illustrating areas to which LBAs are assigned by the magnetic disk device 1 of the first embodiment. In this diagram, the hatched area 165 is an area consisting of sectors to which LBAs are assigned. The white areas 170 and 180 are groups of sectors to which no LBAs are assigned.

[0062] In the band area 130a, an LBA is not assigned to an area 170 consisting of sectors with low recording quality. Instead, an LBA is assigned to all of the surplus sectors constituting the surplus sector group 150 of the band area 130a shown in Fig. 8, except for a spare sector group 180 consisting of a predetermined number of spare sectors on the band end sector side shown in Fig. 9.

[0063] Similarly, in the band area 130b, an LBA is not assigned to an area 170 consisting of sectors with low recording quality. Instead, an LBA is assigned to all of the surplus sectors constituting the surplus sector group 150 of the band area 130b shown in Fig. 8, except for a spare sector group 180 consisting of a predetermined number of spare sectors on the end sector side of the band shown in Fig. 9.

[0064] A spare sector group 180 consisting of a predetermined number of spare sectors is provided on the band end sector side in each band area 130. The spare sectors are provided in case a sector that is difficult to use appears in the band area 130 after shipping.

[0065] If, after shipment, any sector to which an LBA is assigned becomes unusable, the SoC 30 replaces the unusable sector with a spare sector included in the same band area 130. Specifically, for example, if a write operation to a sector (referred to as a first sector) to which an LBA is assigned fails a predetermined number of times in succession, the SoC 30 registers the first sector as an unusable sector. Then, the SoC 30 does not perform a write operation to the first sector, but resumes the write operation from the sector next to the first sector. Because the set capacity of the band area 130 is fixed, when the first sector is designated as an unusable sector, the LBA is assigned to a spare sector (referred to as a second sector) in the spare sector group 180, and the second sector is used as a data storage destination.

[0066] Although the spare sector group 180 is provided in the band area 130 here, the spare sector group 180 does not necessarily have to be provided in the band area 130. If the spare sector group 180 is not provided in the band area 130, an LBA may be assigned to all sectors of the last track TR of the band area 130.

[0067] In this way, by providing a number of spare sectors greater than or equal to 0 in each band area 130, if the number of surplus sectors included in the surplus sector group 150 is a first number, LBAs are assigned to a second number of surplus sectors out of the first number of surplus sectors, which is a number greater than 0 and less than or equal to the first number, in place of sectors with low recording quality.

[0068] The inspection of the recording quality (hereinafter referred to as quality inspection) is carried out by, for example, an inspection device.

[0069] FIG. 10 is a diagram for explaining the inspection device 3 of the first embodiment.

[0070] The magnetic disk device 1 is connected to an inspection device 3. The inspection device 3 may have the same configuration as a normal computer, for example, having a processor and a storage device. The processor of the inspection device 3 inspects the recording quality of all sectors on the magnetic disk 11 of the magnetic disk device 1 connected to it. The processor of the inspection device 3 generates quality information 41 that records the inspection results of the recording quality, and stores the generated quality information 41 in a storage device 40 provided in the magnetic disk device 1. The storage device 40 is not limited to a specific storage device. The storage device 40 may be, for example, FROM 28 or the magnetic disk 11.

[0071] 10, one magnetic disk device 1 is connected to the inspection device 3. A plurality of magnetic disk devices 1 may be connected to the inspection device 3. The inspection device 3 may be configured to inspect a plurality of magnetic disk devices 1 in parallel.

[0072] FIG. 11 is a flowchart showing an example of the operation of quality inspection by the inspection device 3 of the first embodiment.

[0073] The processor of the inspection device 3 writes data to and reads data from all sectors of the magnetic disk device 1 connected to the inspection device 3, thereby inspecting the quality of all sectors (S101).

[0074] For example, the processor of the inspection device 3 calculates the number of errors contained in the read data for each sector by comparing the write data sent to the magnetic disk device 1 with the read data received from the magnetic disk 11 for each sector. Then, the number of errors contained in the read data calculated for each sector is used as an index representing the recording quality of each sector.

[0075] The method for inspecting the quality of all sectors is not limited to the above method.

[0076] The processor of the inspection device 3 records the results of the quality inspection of all sectors in the quality information 41 (S102), and stores the quality information 41 in the storage device 40 of the magnetic disk device 1 (S103). Then, the quality inspection operation is completed.

[0077] The configuration of the quality information 41 is not limited to a specific configuration. The quality information 41 may have a configuration in which an index representing the recording quality is recorded for each sector. The index representing the recording quality may be the number of errors included in the read data, or may be numerical information that can take multiple levels calculated based on the number of errors included in the read data.

[0078] FIG. 12 is a flowchart showing an example of the operation of the magnetic disk device 1 of the first embodiment.

[0079] First, the SoC 30 sets multiple band areas 130 on the magnetic disk 11 based on a set capacity (i.e., a set value of the storage capacity per band area 130) and a set value of the recording density (TPI and BPI) (S201). The SoC 30 calculates the capacity per track TR based on the set value of the recording density. Then, the SoC 30 performs an operation for setting a group of multiple contiguously arranged tracks TR as one band area 130 for all band areas 130. At this time, the SoC 30 sets each band area 130 so that, for example, the size of the surplus surplus sector group 150 in each band area 130 does not exceed the size of one track TR. Note that the size of the surplus surplus sector group 150 does not necessarily have to be equal to or smaller than the size of one track TR.

[0080] Next, the SoC 30 selects one of the set band regions 130 (S202). The selected band region 130 is referred to as a target band region.

[0081] The SoC 30 identifies the TPI and BPI of the target band area (S203), and calculates the number Nr of surplus sectors in the target band area excluding sectors designated as spare sectors (S204). The total number of surplus sectors in the target band area is an example of a first number. The number Nr is an example of a second number.

[0082] Based on the quality information 41, the SoC 30 selects Nr sectors with the lowest quality within the target band area (S205).

[0083] In the process of S205, the SoC 30 may select Nr sectors with the lowest quality from all sectors included in tracks TR from the first track TR to the track TR adjacent to the last track TR among the multiple tracks TR included in the target band area, because the sectors included in the last track TR have a higher recording quality than the recording quality indicated by the quality inspection result.

[0084] After the process of S205, the SoC 30 sets the selected Nr sectors as unusable sectors (S206).

[0085] Next, the SoC 30 assigns LBAs to each sector in order starting from the first sector of the band (S207).

[0086] In the process of S207, SoC 30 assigns LBAs to each sector so that the LBA values ​​are in ascending order in the order of the sectors. However, SoC 30 skips assigning LBAs to unusable sectors. In other words, SoC 30 assigns LBAs to a group of sectors whose number corresponds to the set capacity and that are not included in the selected Nr sectors from among the group of sectors included in band area 130. As a result, LBAs are assigned to all sectors except for unusable sectors and spare sectors, as described with reference to FIG. 9.

[0087] The SoC 30 determines whether or not there remains any band area 130 that has not been selected as a target band area (S208).

[0088] If there are any remaining band areas 130 that have not been selected as target band areas (S208: Yes), the SoC 30 selects one of the band areas 130 that have not been selected as target band areas as the target band area (S209), and then the control transitions to S203.

[0089] If there are no remaining band areas 130 that have not been selected as target band areas (S208: No), the SoC 30 ends the operation.

[0090] The correspondence between each sector and LBA is recorded in management information in a predetermined nonvolatile storage area (for example, FROM 28) by the SoC 30. When an access command is received from the host 2 after shipment, the SoC 30 can identify the sector corresponding to the LBA included in the access command based on the management information.

[0091] As described above, according to the first embodiment, the SoC 30 calculates the number Nr of surplus sectors corresponding to the capacity obtained by subtracting the set recording density value from the set capacity of the band area 130, based on the set capacity and the set recording density value of the band area 130 (see, for example, S204 in FIG. 12). The SoC 30 selects Nr sectors based on the quality information 41 in which the results of the quality inspection are recorded (see, for example, S205 in FIG. 12). The SoC 30 assigns LBAs to a group of sectors, the number of which corresponds to the set capacity and which are not included in the selected Nr sectors from the group of sectors included in the band area 130 (see, for example, S207 in FIG. 12).

[0092] Therefore, the recording quality in the band area 130 is improved, and the recording quality of the magnetic disk device 1 as a whole is improved.

[0093] Furthermore, in the first embodiment, the SoC 30 selects Nr sectors with the lowest recording quality from the group of sectors included in the band area 130 (see, for example, S205 in FIG. 12).

[0094] Since the sectors of the last track TR, which have good recording quality, are used instead of the Nr sectors with the lowest recording quality among the group of sectors included in the band area 130, the recording quality in the band area 130 is improved, and the recording quality of the magnetic disk device 1 as a whole is improved.

[0095] It should be noted that the SoC 30 does not necessarily have to select the Nr sectors with the lowest recording quality, but may be configured to select the Nr sectors from among sectors whose recording quality does not meet a predetermined level.

[0096] Also, as described above, SoC30 may select the Nr sectors with the lowest quality from all sectors included in tracks TR from the first track TR to the track TR adjacent to the last track TR among the multiple tracks TR included in band area 130.

[0097] Therefore, instead of the Nr sectors with the lowest recording quality among the group of sectors included in the band area 130, the sectors of the end track TR with good recording quality are used, thereby improving the recording quality in the band area 130 and improving the recording quality of the magnetic disk device 1 as a whole.

[0098] (Second embodiment) In the first embodiment, a quality inspection was performed on all sectors of the magnetic disk device 1. The quality inspection is not limited to all sectors. Any quality inspection result can be used as long as it is related to the recording quality of the sectors included in the band area 130. In the second embodiment, variations of the quality inspection will be described.

[0099] For example, in the process of forming a magnetic layer on the surface of the magnetic disk 11, the thickness of the magnetic layer may be uneven in the circumferential direction, which reduces the recording quality in a narrow region extending in the radial direction.

[0100] Therefore, in the second embodiment, the inspection device 3 performs quality inspection on a plurality of sectors included in at least one track TR (hereinafter referred to as inspection track TR) among a plurality of tracks TR provided on the magnetic disk 11. The SoC 30 of the magnetic disk device 1 selects Nr sectors from a narrow area (hereinafter referred to as partial area) extending in the radial direction that includes the sector with the lowest recording quality among the plurality of sectors included in the inspection track TR.

[0101] The following describes the differences from the first embodiment. The same matters as those in the first embodiment will be omitted or will be explained briefly.

[0102] FIG. 13 is a flowchart showing an example of the operation of quality inspection by the inspection device 3 of the second embodiment.

[0103] The processor of the inspection device 3 performs a quality inspection of all sectors included in the inspection track TR by writing data to and reading data from all sectors included in the inspection track TR on the magnetic disk device 1 connected to the inspection device 3 (S301).

[0104] Of the multiple tracks TR provided on the recording surface 100 of the magnetic disk 11, at least one track TR is set as a test track TR.

[0105] The processor of the inspection device 3 records the results of the quality inspection in the quality information 41 (S302), and stores the quality information 41 in the storage device 40 of the magnetic disk device 1 (S303). Then, the quality inspection operation is completed.

[0106] FIG. 14 is a flowchart showing an example of the operation of the magnetic disk device 1 of the second embodiment.

[0107] The SoC 30 executes the same processes as those in S201 to S204 in FIG. 12 in S401 to S404.

[0108] In the process of S405, the SoC 30 selects Nr sectors in the target band area from the partial area. As described above, the partial area is a narrow area extending in the radial direction that includes the sector with the lowest recording quality in the test track TR. For example, the partial area extends from the innermost end of the recording surface 100 to the outermost end of the recording surface 100.

[0109] As in the process of S205, the SoC 30 may select Nr sectors from all sectors included in the tracks TR from the first track TR to the track TR adjacent to the last track TR in the partial area, because the sectors included in the last track TR have a higher recording quality than the recording quality indicated by the quality inspection result.

[0110] After the process of S405, the SoC 30 executes the same processes as those of S206 to S209 in S406 to S409, and then ends the operation.

[0111] 15 is a diagram illustrating areas to which LBAs are assigned by the magnetic disk device 1 of the second embodiment. As shown in this diagram, area 170, which is a group of sectors arranged in the radial direction, is determined to have low recording quality, and no LBA is assigned to it. However, because the sectors included in the end track TR have relatively high recording quality, an LBA is assigned to area 171, which is a sector included in the end track TR.

[0112] As described above, according to the second embodiment, the quality inspection is an inspection of a plurality of sectors included in at least one track TR among a plurality of tracks TR provided on the magnetic disk 11. The SoC 30 of the magnetic disk device 1 selects Nr sectors from a narrow area (hereinafter, a partial area) extending in the radial direction that includes the sector with the lowest recording quality among the plurality of sectors included in the inspection track TR.

[0113] It is possible to improve the recording quality of the entire magnetic disk device 1 based on the results of a quality inspection of some of the sectors among all the sectors provided on the magnetic disk 11. Since the quality inspection is not performed on all the sectors provided on the magnetic disk 11, the time required for the quality inspection is reduced.

[0114] In the second embodiment, the SoC 30 may also select the Nr sectors with the lowest quality from all sectors included in the tracks TR from the first track TR to the track TR adjacent to the last track TR among the multiple tracks TR included in the band area 130.

[0115] Therefore, instead of the Nr sectors with the lowest recording quality among the group of sectors included in the band area 130, the sectors of the end track TR with good recording quality are used, thereby improving the recording quality in the band area 130 and improving the recording quality of the magnetic disk device 1 as a whole.

[0116] According to the first and second embodiments, the magnetic disk device 1 can exhibit the following characteristics. That is, the number of sectors to which no LBA is assigned that are included in the end track TR is the same across multiple band areas 130. According to the example shown in Fig. 9, the same number of spare sectors are provided for band area 130a and band area 130b. In each of band areas 130a and 130b, LBAs are assigned to the surplus sectors included in the end track TR other than the spare sectors, so the number of sectors to which no LBA is assigned that are included in the end track TR of band area 130a is the same as the number of sectors to which no LBA is assigned that are included in the end track TR of band area 130b.

[0117] In the examples described in the first and second embodiments, of the multiple storage areas 110 provided on the recording surface 100 of the magnetic disk 11, all storage areas 110 except for the media cache area 120 are used as band areas 130 to which data is written using SMR. The techniques of the first and second embodiments can also be applied to magnetic disk devices in which the multiple storage areas 110 include a mixture of band areas 130 to which data is written using SMR and areas to which data is written using CMR.

[0118] Furthermore, the techniques of the first and second embodiments can also be applied to a magnetic disk drive that can switch the recording method between SMR and CMR during operation. In such a magnetic disk drive, when the SoC sets a band area where data is written using SMR, it executes the processes of S203 to S207 shown in Fig. 12 or S403 to S407 shown in Fig. 14 for that band area.

[0119] In the examples described in the first and second embodiments, the inspection device 3 performs the quality inspection, and the SoC 30 of the magnetic disk device 1 acquires the quality inspection results from the quality information 41 (see, for example, S205 in FIG. 12 and S405 in FIG. 14). The SoC 30 may acquire the quality inspection results by performing the quality inspection. For example, the SoC 30 may be configured to perform the series of operations shown in FIG. 11 or 13.

[0120] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0121] 1 magnetic disk device, 2 host, 3 inspection equipment, 11 magnetic disk, 12 SPM, 13 lamp, 15 actuator arm, 22 magnetic head, 22r read head, 22w write head, 23 HDC, 24 preamplifier, 25 RWC, 26 processor, 28 FROM, 29 DRAM, 30 SoC, 40 storage device, 41 quality information, 100 recording surface, 110 storage area, 120 media cache area, 130, 130a, 130b band area, 140 guard area, 150 surplus sector group, 160, 165, 170, 171 area, 180 spare sector group.

Claims

1. obtaining a result of a quality inspection relating to the recording quality of a first plurality of sectors included in a first storage area of ​​a magnetic disk provided in a magnetic disk device, the first storage area including a first plurality of tracks on which data is written using an SMR (Shingled Magnetic Recording) method, and a plurality of different sectors from the first plurality of sectors being provided on each of the first plurality of tracks; calculating a first number, which is the number of sectors corresponding to a capacity obtained by subtracting the set capacity from the actual capacity of the first storage area, based on a set capacity of the first storage area and a set value of the recording density of the first storage area; selecting a second number of sectors from the first plurality of sectors based on the result, the second number being greater than 0 and less than or equal to the first number; assigning addresses usable by a host connected to the magnetic disk device to a group of sectors of the first plurality of sectors, the number of which corresponds to the set capacity and is not included in the second number of sectors; A method comprising:

2. the results are results of quality inspection of all sectors of the first plurality of sectors; the selecting comprises selecting the second number of sectors having the lowest recording quality from the first plurality of sectors; The method of claim 1.

3. a second plurality of tracks including the first plurality of tracks is provided on the magnetic disk; the result is a result of a quality inspection of a second plurality of sectors, the second plurality of sectors being a plurality of sectors included in one of the second plurality of tracks; the selecting includes selecting the second number of sectors included in a partial area extending in a radial direction of the magnetic disk, the partial area including a sector having the lowest recording quality among the second plurality of sectors; The method of claim 1.

4. a direction of writing data to the first plurality of tracks in the SMR method is set from a first track, which is the track closest to one end of the first storage area in the radial direction among the first plurality of tracks, to a second track, which is the track closest to the other end of the first storage area in the radial direction among the first plurality of tracks; the selecting includes selecting the second number of sectors from a third plurality of sectors; the third plurality of sectors is a group of sectors included in the third plurality of tracks from the first track to the third track, the third track is a track adjacent to the second track among the first plurality of tracks; The method according to any one of claims 1 to 3.

5. obtaining the second number by subtracting a set number greater than 0 from the first number; The method of any one of claims 1 to 3, further comprising:

6. a magnetic disk provided with a first storage area including a plurality of second tracks among a plurality of first tracks, each of which has a plurality of sectors, and a second storage area including a plurality of third tracks different from the plurality of second tracks among the plurality of first tracks; A magnetic head; a controller that writes data to the plurality of second tracks using the magnetic head in an SMR system and writes data to the plurality of third tracks using the magnetic head in an SMR system; Equipped with the number of sectors to which addresses usable by the host are not assigned and included in the second track to which data is last written in a write operation to the plurality of second tracks using the SMR method matches the number of sectors to which addresses usable by the host are not assigned and included in the third track to which data is last written in a write operation to the plurality of third tracks using the SMR method; Magnetic disk device.

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