Magnetic disk device and method

Abstract

To provide a magnetic disk device and a method capable of suitably writing data to a magnetic disk.SOLUTION: A controller of a magnetic disk device reads band data from a band area in which a plurality of first tracks are provided, and updates the read band data with write data received from a host. When the updated portion of the updated band data is not included in the data of the head track in the band area, the controller writes data, which is from the track that is the destination of writing the data among the updated band data including the updated portion to the tail track, by shifting each track location, which is from the track that is the destination of writing the data including the updated portion to the tail track, by a predetermined amount in the tail direction.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] This embodiment relates to a magnetic disk device and method.

Background Art

[0002] Conventionally, in a magnetic disk device, a recording method called SMR (Shingled Magnetic Recording) is known. According to SMR, the track pitch can be made narrower than the width of the write head, thereby improving the recording density.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One embodiment aims to provide a magnetic disk device and method capable of preferably writing data to a magnetic disk.

Means for Solving the Problems

[0005] According to one embodiment, a magnetic disk drive includes a magnetic disk and a controller. The magnetic disk has a first storage area. A plurality of first tracks in which data is written in the SMR format are provided in the first storage area. The writing direction of data in the SMR format for the plurality of first tracks is set in the direction from the second track to the third track. The second track is the first track closest to the first end which is one end in the radial direction of the first storage area among the plurality of first tracks. The third track is the first track closest to the second end which is the other end in the radial direction of the first storage area among the plurality of first tracks. The controller reads first data which is data stored in the plurality of first tracks, and updates the read first data, which is second data, with third data which is data received from a host. When the updated portion included in the updated second data, which is fourth data, is not included in the data of the second track, the controller operates as follows. That is, the controller writes the data from the fourth track to the third track, which is the first track where the data including the updated portion in the fourth data is to be written, while shifting the positions of each of the first tracks from the fourth track to the third track by a first amount in the direction of the second end.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, with reference to the accompanying drawings, a magnetic disk device and method according to an embodiment will be described in detail. Note that the present invention is not limited by this embodiment.

[0008] (Embodiment) FIG. 1 is a diagram showing an example of the configuration of the magnetic disk device 1 of the embodiment.

[0009] The magnetic disk device 1 is connected to the host 2. The magnetic disk device 1 can receive an access command from the host 2. The access command includes a write command and a read command.

[0010] The magnetic disk device 1 includes a magnetic disk 11 having a magnetic layer formed on its surface. The magnetic disk device 1 performs access to the magnetic disk 11 according to an access command. The access includes writing data and reading data.

[0011] Writing and reading of data are performed by the magnetic head 22. Specifically, in addition to the magnetic disk 11, the magnetic disk drive 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, a magnetic head 22, a hard disk controller (HDC) 23, a preamplifier 24, a read / write channel (RWC) 25, a processor 26, a FROM (Flash Read Only Memory) 28, and a DRAM (Dynamic Random Access Memory) 29.

[0012] The magnetic disk 11 is rotated at a predetermined rotational speed by the coaxially attached SPM 12.

[0013] The SVC 21 is an integrated circuit having a function as a driver for driving the SPM 12 and the VCM 16. The processor 26 controls the rotation of the SPM 12 and the rotation of the VCM 16 via the SVC 21.

[0014] The magnetic head 22 performs writing and reading with respect to the magnetic disk 11 by the write head 22w and the read head 22r provided therein. Further, the magnetic head 22 is attached to the tip of the actuator arm 15. The magnetic head 22 is moved in the radial direction of the magnetic disk 11 by the VCM 16 driven by the SVC 21. Note that one or both of the write head 22w and the read head 22r provided in the magnetic head 22 may be provided in plural for each single magnetic head 22.

[0015] When the rotation of the magnetic disk 11 stops, etc., the magnetic head 22 is moved onto the ramp 13. The ramp 13 is configured to hold the magnetic head 22 at a position separated from the magnetic disk 11.

[0016] The preamplifier 24 is an integrated circuit that writes and reads data via the magnetic head 22. During the read operation, the preamplifier 24 amplifies and outputs the signal read by the magnetic head 22 from the magnetic disk 11, and supplies it to the RWC 25. Also, during the write operation, the preamplifier 24 amplifies the signal corresponding to the data to be written supplied from the RWC 25, and supplies it to the magnetic head 22.

[0017] The HDC 23 controls the transmission and reception of data with the host 2 via the I / F bus, and controls the DRAM 29, etc.

[0018] The DRAM 29 is used as a buffer for data transmitted and received with the host 2. For example, the DRAM 29 is used to temporarily store the data to be written, or the data read from the magnetic disk 11.

[0019] Also, the DRAM 29 is used as an operating memory by the processor 26. The DRAM 29 is used as an area where the firmware program is loaded, and an area where various data are temporarily stored. In particular, the DRAM 29 is used as a buffer for data transfer between the host 2 and the magnetic disk 11.

[0020] The RWC 25 modulates the data to be written supplied from the HDC 23 and supplies it to the preamplifier 24. Also, the RWC 25 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 as digital data to the HDC 23.

[0021] The processor 26 is, for example, a CPU (Central Processing Unit). The FROM (Flash Read Only Memory) 28 and the DRAM 29 are connected to the processor 26.

[0022] FROM28 stores a firmware program, various setting information, and the like. Note that the firmware program may be stored in the magnetic disk 11.

[0023] The processor 26 performs overall control of this magnetic disk device 1 according to the firmware program stored in FROM28 or the magnetic disk 11. For example, the processor 26 loads the firmware program from FROM28 or the magnetic disk 11 into the DRAM 29, and executes control of the SVC 21, the preamplifier 24, the RWC 25, the HDC 23, etc. according to the firmware program loaded into the DRAM 29.

[0024] Note that part or all of the functions of the processor 26 may be realized by a hardware circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0025] The HDC 23, the RWC 25, and the processor 26 are configured as an SoC (System-On-a-Chip) 30, which is an integrated circuit. In addition to these, the SoC 30 may include other elements (for example, FROM28, or DRAM 29, etc.). Note that the SoC 30 is an example of a controller.

[0026] FIG. 2 is a diagram showing an example of the configuration of the magnetic disk 11 according to the embodiment. Servo information is written, for example, by a servo writer or the like on the magnetic layer formed on the surface of the magnetic disk 11 before shipment. The servo information may be written on the magnetic layer by self servo write. The servo information includes sector / cylinder information, a burst pattern, and a post code. The sector / cylinder information gives servo addresses in the circumferential direction and the radial direction of the magnetic disk 11. The burst pattern gives the amount of displacement of the magnetic head 22 from the position indicated by the servo address. The post code is data for correcting RRO (Repeatable RunOut). The SoC 30 reads the servo information using the magnetic head 22 and executes a seek operation and a tracking operation based on the read servo information. The seek operation is an operation of moving the magnetic head 22 in the radial direction. The tracking operation is an operation of maintaining the magnetic head 22 on the target track. Note that the servo information may be written on the magnetic disk 11 after shipment by self servo write (SSW).

[0027] FIG. 2 shows a servo zone 11a arranged radially as an example of the arrangement of servo zones in which servo information is written. A plurality of concentric tracks 11b are provided at a predetermined pitch in the radial direction of the magnetic disk 11. A large number of sectors are continuously formed on the circumference of each track 11b. Data writing and reading are executed for each sector by the magnetic head 22.

[0028] As recording methods, that is, methods of writing data to the magnetic disk 11, there are several types of recording methods. The plurality of recording methods include CMR and SMR.

[0029] FIG. 3 is a diagram for explaining the SMR of the embodiment. In SMR, writing of data (referred to as first data) on a certain track 11b is executed, and then writing of data (referred to as second data) on a track 11b that is radially adjacent to the track 11b is executed. When writing the second data, the second data is written so that a part of the second data overlaps a part of the first data. That is, according to SMR, data on one of two tracks 11b that are adjacent to each other in the radial direction of the magnetic disk 11 is written so as to overlap a part of the data on the other track 11b among the two tracks 11b.

[0030] As an example, in FIG. 3, as three tracks 11b, track #M-1, track #M, and track #M+1 are depicted. Track #M-1 and track #M are adjacent to each other. Track #M and track #M+1 are adjacent to each other. In this example, writing is performed in the order of data on track #M-1, data on track #M, and data on track #M+1. The data on track #M is written so as to radially partially overlap the data on track #M-1. The data on track #M+1 is written so as to radially partially overlap the data on track #M. That is, according to SMR, it is repeated that data on one track 11b overlaps a part of the data on an adjacent track 11b on which data has already been written.

[0031] Since data is written by the above method according to SMR, the track pitch TP is made narrower than the element width (WHw) of the write head 22w of the magnetic head 22. As a result, the recording density is improved.

[0032] However, according to SMR, since the track pitch TP is narrow, it is susceptible to the influence of ATE (Adjacent Track Erasure). Therefore, in principle, the data for a plurality of radially continuous tracks 11b are updated in a batch. The area where a plurality of tracks 11b for batch update are provided is called a band area. The update can be paraphrased as a change or a rewrite. Note that the band area is an example of the first storage area and the second storage area.

[0033] Also, according to SMR, since the data of one track 11b is written so as to overlap a part of the data of the adjacent track 11b where data has already been written, for a plurality of continuous tracks 11b, it can be written only in one of the directions from the inner side to the outer side and from the outer side to the inner side. The writing order for such a plurality of radially continuous tracks 11b may be common for all band areas, or may be determined for each band area.

[0034] FIG. 4 is a diagram for explaining the CMR of the embodiment. As shown in this figure, according to CMR, the data of each track 11b is arranged so as not to overlap the data of the tracks 11b adjacent in the radial direction. In other words, CMR is a method in which the data of two tracks 11b adjacent to each other in the radial direction of the magnetic disk 11 is written so as not to overlap each other.

[0035] For example, in FIG. 4, as three tracks 11b, track #N - 1, track #N, and track #N + 1 are depicted. Track #N - 1 and track #N are arranged to be separated from each other in the radial direction. Track #N and track #N + 1 are arranged to be separated from each other in the radial direction. That is, track #N - 1, track #N, and track #N + 1 are arranged so that the data of two adjacent tracks 11b do not overlap each other.

[0036] According to CMR, the track pitch TP is equal to or larger than the element width (WHw) of the write head 22w, so that data at any position can be updated. Therefore, according to CMR, the random access performance is high.

[0037] FIG. 5 and FIG. 6 are diagrams showing examples of a plurality of band regions provided in the magnetic disk 11 of the embodiment.

[0038] The recording surface 100 of the magnetic disk 11, that is, the region where the tracks 11b can be arranged, is divided in the radial direction into a plurality of storage regions 110. The plurality of storage regions 110 include one media cache region 120 and a plurality of band regions 130. Between the storage regions 110, a region called a guard region 140 that cannot be specified as a write destination from the host 2 is provided.

[0039] The storage region 110 provided on the outermost peripheral side in the radial direction within the recording surface is set as the media cache region 120. The media cache region 120 is a storage region used as a temporary storage location for data. Data is written to the media cache region 120 by CMR. Note that the position of the media cache region 120 is not limited to the outermost peripheral side. Also, two or more media cache regions 120 may be provided on the recording surface.

[0040] Two or more of the plurality of storage regions 110 are set as band regions 130. Each band region 130 is provided with a plurality of tracks 11b. In each band region 130, data is written to all the tracks 11b in the SMR method. When writing data to each band region 130, it is prohibited to write data to the adjacent band region 130 across the guard region 140 from the band region 130 that is the write destination.

[0041] Logical addresses that can be used by host 2 are mapped to each band area 130. Therefore, each band area 130 serves as the final storage location for data (referred to as write data) for which a write is requested from host 2. Note that the plurality of band areas 130 may include a band area 130 to which a logical address that can be used by host 2 is not mapped.

[0042] When a write is performed on all tracks 11b of one band area 130, the track 11b where data is first written is referred to as the head track of the band area 130, and the track 11b where data is last written is referred to as the end track of the band area 130. Among all tracks 11b of one band area 130, tracks 11b other than the head track and the end track are referred to as intermediate tracks 11b of the band area 130. In one band area 130, each track 11b from a certain track 11b (referred to as the first track 11b) that is an intermediate track 11b of the band area 130 to the end track of the band area 130 is referred to as a track after the first track 11b of the band area 130.

[0043] Of the two radial ends of one band area 130, the end on which the head track of the one band area 130 is disposed is referred to as the head of the band area 130. Of the two radial ends of one band area 130, the end on the side opposite to the head is referred to as the end. In one band area 130, a track 11b adjacent to the first track 11b on the head side of the band area 130 is referred to as the track 11b immediately before the first track 11b. In one band area 130, a track 11b adjacent to the first track 11b on the end side of the band area 130 is referred to as the track 11b immediately after the first track 11b.

[0044] As described above, according to the SMR, in principle, data is updated in units of the band area 130. However, if the updated portion is included only in the data after the track 11b in the middle of the band area 130, it can be considered that the update for one or more consecutive tracks 11b that do not include the updated portion on the leading side is unnecessary.

[0045] Therefore, in the embodiment, when the updated portion is not included in the data of one or more consecutive tracks 11b on the leading side of the band area 130, the SoC 30 does not update these one or more tracks 11b. As a result, the time required for the update is reduced compared to the case where data is updated in units of the band area 130, and the write performance is improved.

[0046] FIG. 7 is a diagram for explaining an example of the operation when data is written from the host 2 executed in the magnetic disk device 1 of the embodiment.

[0047] In the magnetic disk device 1, the write data received from the host 2 is first stored in the DRAM 29 by the HDC 23 (S1). A buffer area is allocated in advance in the DRAM 29, and in S1, the write data is stored in this buffer area.

[0048] Subsequently, in order to prevent the buffer area from running out of space or the write data in the DRAM 29 from being lost from the magnetic disk device 1 due to a power failure or the like, the write data is transferred from the DRAM 29 to the media cache area 120 (S2). At this time, the write data is written to the media cache area 120 in the CMR method with high random access performance.

[0049] Thereafter, all data is read from the band area 130, which is the final write destination of the write data (S3). All data in one band area 130 is referred to as band data. The band data read in S3 may be temporarily stored in the DRAM 29 or may be temporarily stored in the media cache area 120. The band data read in S3 is referred to as the pre-update band data.

[0050] In FIG. 7, six tracks 11b are set in the band area 130, which is the final storage destination of the write data, and the data of each track 11b constituting the band data is arranged in the array order of the tracks 11b and shown. The head track of the band area 130 is referred to as the head track HT, and the data of the head track HT is referred to as the head track data HTD.

[0051] The pre-update band data is compared with the write data temporarily stored in the media cache area 120, whereby the post-update band data is generated (S4). At this time, confirmation of the updated part (hereinafter referred to as the update part) included in the post-update band data is performed. In FIG. 6, the hatched part of the post-update band data indicates the update part.

[0052] In the example shown in FIG. 7, the data of three consecutive tracks 11b including the head track HT, that is, the data of three tracks 11b from the head track HT to the third track, does not include the update part, and the update part is included in the data of three tracks 11b from the fourth track to the sixth track. Therefore, the data of three tracks 11b from the fourth track 11b to the sixth track, which is the last track, is written to the band area 130 in an overwrite format (S5). At this time, data writing for the three consecutive tracks 11b including the head track HT is not performed. That is, writing for updating data is started for the fourth track 11b, and after the fourth track 11b, writing for updating is executed in this order for the fifth track 11b and the sixth track 11b, which is the last track.

[0053] As described above, when the data of one or more consecutive tracks 11b including the leading track HT does not include an update portion, instead of updating all the tracks 11b in the band area 130, an update is performed for each track 11b after the track 11b including the update portion.

[0054] Furthermore, in the embodiment, when starting an update from a track 11b in the middle of one band area 130, the positions of each track 11b after the track 11b from which the update is started are offset by a predetermined amount toward the end side.

[0055] When starting an update from a track 11b in the middle of one band area 130, the track 11b immediately before the track 11b from which the update is started (referred to as the second track 11b) may be affected by ATE, making it difficult to read the data of the second track 11b. When it becomes difficult to read the data of the second track 11b, a read retry may occur when reading the data of the second track 11b, which may deteriorate the read performance.

[0056] In the embodiment, by offsetting the positions of each track 11b after the track 11b from which the update is started in the direction of the end of the band area 130, the influence of ATE received by the second track 11b is reduced, and the deterioration of the read performance caused by the read retry of the data of the second track 11b can be suppressed.

[0057] FIG. 8 is a diagram for explaining an example of an operation of updating data from a track 11b in the middle of one band area 130 executed in the magnetic disk device 1 of the embodiment.

[0058] In the example shown in FIG. 8, six tracks 11b are provided in the band area 130. The data HTD of the leading track HT is denoted as data TD#1, the data of the second track 11b is denoted as data TD#2, the data of the third track 11b is denoted as data TD#3, the data of the fourth track 11b is denoted as data TD#4, the data of the fifth track 11b is denoted as data TD#5, and the data of the sixth track 11b is denoted as data TD#6. The sixth track 11b corresponds to the trailing track.

[0059] In this example, a case where an update starts from the fourth track 11b is shown. In such a case, the data TD#4 of the fourth track 11b is written at a position offset by D ofs only in the direction from the original position of the fourth track 11b towards the end. Subsequently, the data TD#5 of the fifth track 11b is written at a position offset by D ofs only in the direction from the original position of the fifth track 11b towards the end. Then, the data TD#6 of the sixth track 11b, which is the trailing track, is written at a position offset by D ofs only in the direction from the original position of the sixth track 11b towards the end.

[0060] The original position of the track 11b is the position of the track 11b when it has never been offset. The original position of the track 11b is set in advance.

[0061] The offset amount D ofs is set so as to reduce the influence of the ATE received by the track 11b immediately before the track 11b where the offset is started. However, the offset amount D ofs is set so that even if an offset is performed on the trailing track, the data of the trailing track is not written across the guard area 140 into the adjacent band area 130.

[0062] The offset amount D ofsis set individually for each band region 130, for example. The positional relationship between the read head 22r and the write head 22w provided on the magnetic head 22 changes according to the skew angle of the magnetic head 22. Also, the track pitch TP and the linear recording density are determined according to the radial position of the magnetic disk 11, the manufacturing variations of the magnetic disk 11, the manufacturing variations of the magnetic head 22, and the like. Therefore, the influence of the ATE can vary according to the magnetic head 22 and the radial position, and so on. The offset amount D ofs is set individually for each band region 130 based on the factors affecting these ATE influences.

[0063] Note that a common value for all the band regions 130 may be set as the offset amount D ofs

[0064] FIG. 9 is a flowchart showing an example of the data write operation executed in the magnetic disk device 1 of the embodiment. The write destination band region 130 is referred to as the target band region 130. Also, it is assumed that the write data is stored in the media cache region 120.

[0065] First, the SoC 30 determines whether data is already stored in the target band region 130 (S101). If no data is stored in the target band region 130 (S101: No), that is, if the target band region 130 is in an empty state, the SoC 30 writes the write data in the media cache region 120 to the target band region 130 (S102), and the write operation ends.

[0066] If data is already stored in the target band region 130 (S101: Yes), the SoC 30 starts updating the band data of the target band region 130.

[0067] Specifically, the SoC 30 reads the band data from the target band region 130 (S103). The SoC 30 compares the read band data with the write data and generates the updated band data (S104). ​

[0068] The temporary storage location for the read band data and the location where the updated band data is generated are not limited to a specific location. For example, the read band data and the updated band data are temporarily stored in the DRAM 29 or the media cache area 120.

[0069] Following the process of S104, the SoC 30 determines whether the data of the leading track in the target band region 130 includes an updated portion (S105). If the data of the leading track in the target band region 130 does not include an updated portion (S105: No), the SoC 30 determines whether the number of updates to the target band region 130 is less than a threshold value (S106).

[0070] As described above, when the SoC 30 starts an update from the track 11b in the middle of one band region 130, by offsetting the positions of each track 11b after the track 11b where the update starts, the influence of the ATE received by the track 11b immediately before the track 11b where the update starts is suppressed. However, if the update from the track 11b in the middle of one band region 130 is executed multiple times, the influence of the ATE received by the track 11b where the update starts accumulates, and it may become difficult to read the data of the track 11b immediately before the track 11b where the update starts. Therefore, in the embodiment, the number of executions of the update from the track 11b in the middle of one band region 130 is limited by a preset threshold value.

[0071] If the number of updates to the target band region 130 is less than the threshold value (S106: Yes), the SoC 30 obtains the offset amount D ofs set for the target band region 130 (S107). The SoC 30 offsets the data of all tracks 11b after the track 11b where the data including the updated portion is to be written among all the tracks 11b in the target band region 130 by the offset amount D ofsLight only at a position shifted toward the trailing end side (S108). Then, the SoC 30 records the track number of the offset start track at a predetermined position (S109).

[0072] In the target band region 130, the offset start track is the track 11b of the data written at a position shifted by the offset amount D toward the trailing end side from the original position. ofs That is, among the tracks 11b of the data written at a position shifted by the offset amount D toward the trailing end side from the original position in the target band region 130, the track 11b closest to the head of the band region 130 is the offset start track. For example, when the process of S108 is executed a plurality of times for a certain band region 130, among the tracks 11b of the data written at a position shifted by the offset amount D toward the trailing end side from the original position by the process of S108 executed a plurality of times, the track 11b closest to the head of the band region 130 is taken as the offset start track. Therefore, in S109, when the update is performed from a track 11b closer to the head than the track 11b already recorded as the offset start track, the track number of the recorded offset start track is updated. When the update is performed from a track 11b closer to the trailing end than the track 11b already recorded as the offset start track, the track number of the recorded offset start track is not updated. ofs Following the process of S109, the SoC 30 increments the update count for the target band region 130 by 1 (S110). Then, the writing operation ends.

[0073] When the data of the head track of the target band region 130 includes an updated portion (S105: Yes), or when the update count for the target band region 130 is not less than the threshold value (S106: No), the SoC 30 writes the updated band data from the head of the target band region 130 (S111). Then, the SoC 30 clears the update count for the target band region 130 and the track number of the recorded offset start track (S112), and the writing operation ends.

[0074]

[0075] ​By the operation shown in FIG. 9, the data of track 11b after the offset start track in each band region 130 is written to a position shifted by the offset amount D from the original position towards the end of the band region 130. Therefore, when the SoC 30 reads data from track 11b after the offset start track, the SoC 30 specifies the position of the data to be read based on the original position of track 11b where the data to be read was written and the offset amount D. Specifically, the SoC 30 specifies, as the position of the data to be read, a position shifted by the offset amount D from the original position of track 11b where the data to be read was written towards the end of the band region 130. ofs Accordingly, when the SoC 30 reads data from track 11b after the offset start track, the SoC 30 specifies the position of the data to be read based on the original position of track 11b where the data to be read was written and the offset amount D. Specifically, the SoC 30 specifies, as the position of the data to be read, a position shifted by the offset amount D from the original position of track 11b where the data to be read was written towards the end of the band region 130. ofs and. Specifically, the SoC 30 reads data from track 11b after the offset start track, and the SoC 30 specifies, as the position of the data to be read, a position shifted by the offset amount D from the original position of track 11b where the data to be read was written towards the end of the band region 130. ofs only in the direction of the end of the band region 130 as the position of the data to be read.

[0076] In the operation example shown in FIG. 9, when the update starts from track 11b in the middle of the band region 130, even if the update is the second or later time, the offset amount from the original position of track 11b is D. When updating a track 11b that has already been shifted from the original position, the SoC 30 may write data to a position shifted by the offset amount D from the position of track 11b immediately before the update. ofs and. When updating a track 11b that has already been shifted from the original position, the SoC 30 may write data to a position shifted by the offset amount D from the position of track 11b immediately before the update. ofs only shifted.

[0077] As described above, according to the embodiment, the SoC 30 reads band data from the band region 130 and updates the read band data with write data (see, for example, S103 and S104 in FIG. 9). When the updated portion of the updated band data is not included in the data of the head track (for example, when it is determined as No in S105 in FIG. 9), the SoC 30 operates as follows. That is, the SoC 30 shifts the data after track 11b, which is the write destination of the data including the updated portion of the updated band data, by the offset amount D in the direction of the end of the band region 130 for each track 11b from track 11b, which is the write destination of the data including the updated portion of the updated band data, to the end track and writes it. ofs only in the direction of the end of the band region 130.

[0078] Compared with the case where data is updated in units of the band region 130, the time required for the update is reduced, improving the write performance. Furthermore, the influence of ATE on the track 11b immediately before the track 11b where the update is started is reduced, and deterioration of the read performance due to read retry can be suppressed. That is, it becomes possible to suitably write data to the magnetic disk.

[0079] Also, according to the embodiment, when the number of times of execution of the update from the track 11b in the middle of the band region 130 reaches the threshold value (for example, when it is determined as No in S106 of FIG. 9), the SoC30 writes the updated band data to the original position of each track 11b.

[0080] Therefore, it is possible to suppress the influence of ATE received by the track 11b immediately before the track 11b where the update is started from accumulating and making it difficult to read data from the track 11b.

[0081] In addition, according to the embodiment, even when the updated portion of the updated band data is included in the data of the head track (for example, when it is determined as Yes in S105 of FIG. 9), the SoC30 writes the updated band data to the original position of each track 11b.

[0082] Also, according to the embodiment, when reading data (referred to as third data) stored in any track 11b from the track 11b where the update is started to the last track, the SoC30 determines the original position of the track 11b where the third data is stored and the offset amount D ofs Based on this, the position of the third data is specified.

[0083] Therefore, the SoC30 can read data written at a position deviated from the original position.

[0084] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0085] 1 Magnetic disk device, 2 Host, 11 Magnetic disk, 11a Servo zone, 11b Track, 12 SPM, 13 Lamp, 15 Actuator arm, 21 SVC, 22 Magnetic head, 22r Read head, 22w Write head, 23 HDC, 24 Preamplifier, 25 RWC, 26 Processor, 28 FROM, 29 DRAM, 100 Recording surface, 110 Storage area, 120 Media cache area, 130 Band area, 140 Guard area.

Claims

1. A magnetic disk having a first memory area, wherein a plurality of first tracks on which data is written in a Shingled Magnetic Recording (SMR) method are provided in the first memory area, and the direction of writing data in the SMR method for the plurality of first tracks is from a second track, which is the first track closest to a first end, which is one end in the radial direction of the first memory area among the plurality of first tracks, to a third track, which is the first track closest to a second end, which is the other end in the radial direction of the first memory area among the plurality of first tracks; and reading first data, which is data stored in the plurality of first tracks; updating the read second data, which is the first data, with third data, which is data received from a host; when an updated portion included in fourth data, which is the updated second data, is not included in the data of the second track, writing data from a fourth track, which is the first track where the data including the updated portion among the fourth data is to be written, to the third track by shifting the positions of each of the first tracks from the fourth track to the third track by a first amount in the direction of the second end; a controller; A magnetic disk device comprising the same.

2. When the number of times of writing from a first track on the side of the second end of the plurality of first tracks rather than the second track by the controller reaches a threshold value, the controller writes the data of the plurality of first tracks to their original positions. The magnetic disk device according to Claim 1.

3. When the updated portion is included in the data of the second track, the controller writes the data of the plurality of first tracks to their original positions. The magnetic disk device according to Claim 1.

4. The controller identifies the position of fifth data, which is data stored in a fifth track, which is any one of the first tracks from the fourth track to the third track, based on the original position of the fifth track and the first amount when reading the fifth data. The magnetic disk device according to Claim 1.

5. The magnetic disk further comprises a plurality of second memory areas each having the same configuration as the first memory area. The value of the first quantity is individually set for each of the plurality of second storage areas. The magnetic disk device according to any one of claims 1 to 4. **Claim 6** Writing data to a plurality of first tracks provided in a first storage area of a magnetic disk in an SMR manner, and the direction of writing data in the SMR manner for the plurality of first tracks is from a second track, which is the first track closest to a first end that is one end in the radial direction of the first storage area among the plurality of first tracks, to a third track, which is the first track closest to a second end that is the other end in the radial direction of the first storage area among the plurality of first tracks. Reading first data, which is data stored in the plurality of first tracks. Updating the second data, which is the read first data, with third data, which is data received from a host. When an updated part included in the fourth data, which is the updated second data, is not included in the data of the second track, data from a fourth track, which is the first track where the data including the updated part of the fourth data is to be written, to the third track among the fourth data is written by shifting the positions of each first track from the fourth track to the third track by a first quantity in the direction of the second end. A method including the above.

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