disk device

Abstract

An embodiment provides a magnetic disk device that improves the efficiency of processing related to writing post-codes. In the magnetic disk device of the embodiment, a first storage area and a second storage area with multiple tracks are provided in the radial direction of the magnetic disk. The first storage area stores multiple post-codes corresponding to the number of the second storage area. A controller controls a first process of reading multiple post-codes from the first storage area and writing the read multiple post-codes to the servo area of ​​the second storage area. In the first process, the controller controls both the second process and the third process while the write head is located on the first track. The second process is a process of writing the first post-code of the multiple read post-codes to the servo area. The third process is a process of writing user data to the data area or reading user data from the data area.

Description

[0001] Related Application

[0002] This application claims the benefit of priority based on Japanese Patent Application No. 2021-44093 (filing date: March 17, 2021), the entire contents of which are incorporated herein by reference. Technical Field

[0003] This embodiment relates to a magnetic disk device. Background Art

[0004] Traditionally, magnetic disk drives have used a method of writing a postcode on each track. This postcode is data used to correct the repeatable runout (RRO) of each track. The RRO is the component of the track's radial deviation from its ideal shape (a perfect circle, in one example) that is synchronized with the disk's rotation. The postcode is also called the RRO bit. Summary of the Invention

[0005] One embodiment provides a magnetic disk device that improves the efficiency of processing related to post-code writing.

[0006] According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, and a controller. A first storage area and a second storage area in which a plurality of tracks are set are provided in the radial direction of the magnetic disk. A plurality of post-codes for correcting positional deviations of the plurality of tracks are stored in the first storage area. A third storage area and a fourth storage area are provided in the circumferential direction of the second storage area. The magnetic head includes a write head for writing to the magnetic disk and a read head for reading from the magnetic disk. The controller performs the following control: performs a first process of reading a plurality of post-codes from the first storage area and writing the read post-codes to the third storage area of ​​the second storage area. In the first process, the controller performs the following control: performs both the second process and the third process while the write head is located on the first track of the plurality of tracks. The second process is a process of writing the first post-code of the read post-codes to the third storage area. The third process is a process of writing user data to the fourth storage area or reading user data from the fourth storage area. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0008] Figure 2 This is a diagram showing an example of the structure of the magnetic disk according to the first embodiment.

[0009] Figure 3This is a schematic diagram for explaining SMR in the track arrangement method used in the magnetic disk device of the first embodiment.

[0010] Figure 4 This is a schematic diagram for explaining CMR in the track arrangement method used in the magnetic disk device according to the first embodiment.

[0011] Figure 5 This is a schematic diagram for explaining an example of setting the track arrangement at a certain timing in the first embodiment.

[0012] Figure 6 It is used to explain the first embodiment. Figure 5 A schematic diagram showing an example of setting track layouts at different timings.

[0013] Figure 7 This is a schematic diagram for explaining an example of the positional relationship between the radial position of the read head and the radial position of the write head in the magnetic disk device according to the first embodiment.

[0014] Figure 8 This is a schematic diagram for explaining the positional relationship between tracks and code tracks of the tracks in the magnetic disk device according to the first embodiment.

[0015] Figure 9 This is a flowchart showing an example of the operation of the magnetic disk device according to the first embodiment.

[0016] Figure 10 This is a schematic diagram for explaining the details of the write permission condition in the second embodiment.

[0017] Figure 11 This is a flowchart showing an example of the operation of the magnetic disk device according to the second embodiment.

[0018] Figure 12 This is a schematic diagram for explaining the post-code correction process according to the third embodiment.

[0019] Figure 13 This is a diagram for explaining conditions for executing RRO learning in parallel with writing in the magnetic disk device according to the third embodiment.

[0020] Figure 14 This is a flowchart showing an example of the operation of the magnetic disk device according to the third embodiment. DETAILED DESCRIPTION

[0021] Hereinafter, the magnetic disk device according to the embodiment will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments.

[0022] (First embodiment)

[0023] A magnetic disk device includes a magnetic disk and a magnetic head. The magnetic disk has multiple tracks arranged radially, and user data is written along each track. Servo areas and data areas are arranged circumferentially on the magnetic disk, and user data is written to the data areas on each track. Information used for positioning the magnetic head is written to the servo areas. This information written to the servo areas includes a postamble.

[0024] There are several known methods for configuring multiple tracks. These include CMR (Conventional Magnetic Recording) and SMR (Shingled Magnetic Recording). Hereinafter, the method for configuring multiple tracks will be referred to as a track configuration method. Track configuration methods are not limited to CMR and SMR.

[0025] The magnetic disk device is configured to switch the track arrangement in a certain storage area on the magnetic disk during operation of the magnetic disk device. Here, as an example, the magnetic disk device can switch between CMR and SMR.

[0026] When the track configuration in a certain storage area (referred to as the target storage area) is switched, the configuration of multiple tracks within the target storage area changes. Therefore, the set of postcodes already written to the target storage area must be overwritten with the set of postcodes corresponding to the target track configuration. Furthermore, the target storage area must be formatted. Formatting refers to writing user data. The user data written during formatting is the user data stored in the target storage area before the track configuration was switched. The user data written during formatting can also be all 1s or all 0s.

[0027] In the first embodiment, the magnetic disk device sequentially positions the magnetic head on each of a plurality of tracks set in a target storage area, that is, a plurality of tracks arranged according to a track arrangement of a switching target. After positioning the magnetic head on one track, the magnetic disk device writes both the post-code to the servo area and the user data to the data area before moving the magnetic head to the next track.

[0028] In this specification, positioning the magnetic head on a track refers to controlling the magnetic head to maintain it on that track. This type of control is called tracking control. In contrast, controlling the magnetic head to move to the target track from a position different from the target track is called seek control.

[0029] That is, in the first embodiment, the magnetic disk device performs seek control to move the magnetic head to a certain track. Then, while performing tracking control to maintain the magnetic head on the certain track, the magnetic disk device performs both post-amble writing and user data writing. After the post-amble writing and user data writing are completed on the certain track, the magnetic disk device performs seek control to move the magnetic head to the next track, performing tracking control to maintain the magnetic head on the next track, and performing both post-amble writing and user data writing.

[0030] As a technique for comparison with the first embodiment, consider the technique of "writing the post-code to all tracks within the target storage area, and then writing the user data to all tracks within the target storage area." This technique is referred to as a comparative example. According to the comparative example, head seek control is required both when writing the post-code and when writing the user data. In other words, two seek controls are required for each track within the target storage area.

[0031] In contrast, according to the first embodiment, under the state of tracking control that the position of the magnetic head is maintained on one track, the writing of the post-code and the writing of the user data are performed. Thus, one seek control is performed on each track in the storage area of ​​the object. In other words, according to the first embodiment, the number of executions of the seek control can be reduced compared with the technology of the comparative example. Thus, the time required for the processing of the writing of the post-code and the writing of the user data is shortened compared with the technology of the comparative example. In other words, the efficiency of the processing related to the writing of the post-code is improved.

[0032] The following describes the details of the first embodiment including the arrangement of each track.

[0033] Figure 1 This is a diagram showing an example of the configuration of the magnetic disk device 1 according to the first embodiment.

[0034] The magnetic disk device 1 is connected to a host computer 40. The magnetic disk device 1 can receive access commands such as write commands and read commands from the host computer 40. In addition to access commands, the magnetic disk device 1 can also receive commands requesting switching of the track arrangement.

[0035] The magnetic disk device 1 includes a magnetic disk 11. The magnetic disk device 1 writes data to the magnetic disk 11 or reads data from the magnetic disk 11 in response to an access command.

[0036] Data is written or read via the magnetic head 22. Specifically, the magnetic disk device 1 includes, in addition to the magnetic disk 11, a spindle motor 12, a ramp 13, an actuator arm 15, a voice coil motor (VCM) 16, a motor driver 21, a magnetic head 22, a hard disk controller (HDC) 23, a preamplifier 24, a read / write channel (RWC) 25, a processor 26, a RAM (Random Access Memory) 27, a FROM (Flash Read Only Memory) 28, and a buffer memory 29.

[0037] The magnetic disk 11 is rotated at a predetermined rotation speed around a rotation axis by a spindle motor 12 . The spindle motor 12 is driven by a motor driver 21 .

[0038] The magnetic head 22 accesses the magnetic disk 11 using its write head 22w and read head 22r. The write head 22w writes to the magnetic disk 11. The read head 22r reads from the magnetic disk 11. The magnetic head 22 is mounted on the front end of the actuator arm 15. The magnetic head 22 is moved radially of the magnetic disk 11 by the VCM 16 driven by the motor driver 21. When the rotation of the magnetic disk 11 is stopped, the magnetic head 22 is moved onto the ramp 13.

[0039] When reading data from the magnetic disk 11 , the preamplifier 24 amplifies and outputs a signal read from the magnetic disk 11 and supplies it to the RWC 25 . Furthermore, the preamplifier 24 amplifies a signal corresponding to write target data supplied from the RWC 25 and supplies it to the magnetic head 22 .

[0040] The HDC 23 controls data transmission and reception with the host computer 40 via the I / F bus, controls the buffer memory 29 , performs error correction processing on read data, and the like.

[0041] The buffer memory 29 is used as a buffer for data transmitted and received with the host 40. For example, the buffer memory 29 is used to temporarily store data written to the magnetic disk 11.

[0042] The buffer memory 29 is composed of, for example, a volatile memory capable of high-speed operation. The type of memory constituting the buffer memory 29 is not limited to a specific type. The buffer memory 29 can be composed of, for example, DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), or a combination thereof.

[0043] The RWC 25 modulates the write target data supplied from the HDC 23 and supplies the data to the preamplifier 24. The RWC 25 also demodulates the signal read from the magnetic disk 11 and supplied from the preamplifier 24 and outputs the signal to the HDC 23 as digital data.

[0044] The processor 26 is, for example, a CPU (Central Processing Unit) and is connected to a RAM 27 , a FROM (Flash Read Only Memory) 28 , and a buffer memory 29 .

[0045] The RAM 27 is composed of, for example, a DRAM, an SRAM, or a combination thereof. The RAM 27 is used as an operation memory by the processor 26. The RAM 27 is used as an area for loading firmware programs and an area for storing various management data.

[0046] FROM 28 is a nonvolatile memory. Processor 26 controls the entire magnetic disk drive 1 according to the firmware program pre-stored in FROM 28 and magnetic disk 11. For example, processor 26 loads the firmware program pre-stored in FROM 28 and magnetic disk 11 into RAM 27 and controls the motor driver 21, preamplifier 24, RWC 25, HDC 23, and the like according to the loaded firmware program.

[0047] Furthermore, the configuration including the HDC 23, the RWC 25, and the processor 26 may also be considered as the controller 30. The controller 30 may also include other elements such as the RAM 27, the FROM 28, and the buffer memory 29.

[0048] Figure 2 This is a diagram showing an example of the structure of the magnetic disk 11 of the first embodiment. Servo information is written in the magnetic layer formed on the surface of the magnetic disk 11, for example, by a servo writer before shipment. The servo information includes sector / cylinder information and a burst pattern. The sector / cylinder information can provide the servo address in the circumferential and radial directions of the magnetic disk 11, and can be used in the seek control for moving the magnetic head 22 to the target track. The burst pattern can be used in the tracking control for maintaining the magnetic head 22 on the target track. In addition, the servo information can also be written to the magnetic disk 11 after shipment by self-servo writing (SSW). Figure 2 , radially arranged servo areas 11a are shown as an example of the arrangement of servo areas in which servo information is written. A plurality of concentric tracks (eg, track 11b in this figure) are set in the radial direction of the magnetic disk 11.

[0049] Furthermore, in addition to the above-mentioned servo information, a post code is also written in the servo area 11a. The post code written in the servo area 11a will be described later.

[0050] In the first embodiment, SMR and CMR are used as examples of multiple track configuration methods. Furthermore, the magnetic disk device 1 is configured to be able to switch the track configuration method of the storage area of ​​the magnetic disk 11 between SMR and CMR. Figure 3 and Figure 4 , to explain SMR and CMR.

[0051] Figure 3 This is a schematic diagram illustrating the SMR track configuration method used in the magnetic disk device 1 according to the first embodiment. SMR is a method in which, when data (referred to as first data) is written to a certain track and then data (referred to as second data) is written to a radially adjacent track, the tracks are configured so that the second data partially overlaps with the first data. In other words, with SMR, data on one of two radially adjacent tracks on the magnetic disk 11 is written so that the data on the other track overlaps with a portion of the data on the other track.

[0052] For example, part of the data on track #2 overlaps with the data on track #1. Furthermore, part of the data on track #3 overlaps with the data on track #2. In other words, with SMR, data on one track repeatedly overlaps part of the data on an adjacent track where data has already been written.

[0053] As a result, the width of each track, in other words, the track pitch TP, is narrower than the width (WHw) of the write head 22w of the magnetic head 22. As a result, the recording density is improved. In other words, SMR can increase the storage capacity compared to CMR, which will be described later.

[0054] However, with SMR, since the track pitch TP is narrower than the width WHw of the write head 22w, if a portion of the multi-track data is updated, the data of the tracks adjacent to the updated data will be destroyed. To prevent data destruction, with SMR, the multi-track data including the portion of data is updated together. The multi-track area updated together can be called a zone or a band. With SMR, due to the update method described above, the random access performance is inferior to that of CMR, which will be described later.

[0055] Figure 4This is a schematic diagram for explaining CMR in the track configuration method used in the magnetic disk device 1 of the first embodiment. As shown in this figure, according to CMR, each track is configured in a manner that does not overlap with the tracks adjacent in the radial direction. In other words, CMR is a method of writing data in a manner that does not overlap with each other in the radial direction of the magnetic disk 11. According to CMR, the width of each track is the same as the width (WHw) of the write head 22w, so data at any position can be updated. Therefore, according to CMR, the storage capacity is smaller than that of SMR, but on the other hand, the random access performance is high.

[0056] Figure 5 This is a schematic diagram for explaining an example of setting a track configuration mode at a certain timing in the first embodiment. In addition, in this figure, it is assumed that the magnetic head 22 moves relative to the magnetic disk 11 in the direction indicated by the arrow 50. In addition, in this figure, it is assumed that four servo areas 11a are included in the circumferential direction, but the number of servo areas 11a included in the circumferential direction is not limited to four.

[0057] like Figure 5 As shown, on the magnetic disk 11, a post-code area 100, a CMR area 110a, and an SMR area 110b are arranged radially. Each area 100, 110a, and 110b is composed of multiple tracks 11b. Guard areas 11c are provided at the boundaries of each area 100, 110a, and 110b. Guard areas 11c are areas where no data is written.

[0058] Furthermore, two or more CMR areas 110 a and two or more SMR areas 110 b can be allocated to the magnetic disk 11 .

[0059] A plurality of tracks 11 b are arranged in the CMR region 110 a in a CMR manner. A plurality of tracks 11 b are arranged in the SMR region 110 b in a SMR manner.

[0060] A post code (PC) is written in each servo area 11a on each track 11b. Servo information (Srv) is also written in each servo area 11a. The controller 30 corrects the positional deviation of each track 11b based on the post code written in each servo area 11a.

[0061] In addition, a data area 11d is provided between the servo areas 11a on each track 11b. The data area 11d is an area where user data can be written. User data is written to the data area 11d of the CMR area 110a and the SMR area 110b.

[0062] The data area 11 d of the post-code area 100 stores a group of CMR post-codes and a group of SMR post-codes sufficient to set at least the entire area of ​​the track 11 b of the magnetic disk 11 .

[0063] Figure 6 It is used to explain the first embodiment. Figure 5 A schematic diagram showing an example of setting track configurations at different timings. More specifically, Figure 6 Shown from Figure 5 The state shown is the setting of the track configuration mode after the track configuration mode of range 60 is switched from SMR to CMR.

[0064] exist Figure 5 In the example shown, three tracks 11b are arranged in an SMR configuration in the area 60. Figure 6 In the example shown, two tracks 11 b arranged in accordance with the CMR configuration are provided in the area 60 .

[0065] Since the track configuration of range 60 is switched, the configuration of each track 11b within range 60 is changed. Therefore, the controller 30 replaces the post-codes within the servo area 11a of range 60 in accordance with the track configuration switch. More specifically, the controller 30 overwrites the post-code for the CMR track configuration, which is the target track configuration, with the servo area 11a of range 60. Thus, after the track configuration of range 60 is switched from SMR to CMR, the controller 30 can correct the positional offset between the two tracks 11b in range 60.

[0066] Generating a post-code requires a significant amount of time. Therefore, in the first embodiment, the controller 30 obtains the CMR post-code used for overlaying from the post-code area 100. This eliminates the need to generate a post-code in response to changes in the track configuration, thereby reducing the time required for changes in the track configuration.

[0067] In addition, the magnetic disk device 1 can also switch the track configuration from CMR to SMR. Figure 6 The state shown switches the track configuration of range 60 from CMR to SMR, and the track configuration becomes Figure 5 When the track arrangement of the range 60 is switched from CMR to SMR, the controller 30 reads the SMR post code for the range 60 from the post code area 100 and overwrites the read SMR post code for the range 60 with the servo area 11a of the range 60. Thus, after the controller 30 switches the track arrangement of the range 60 from CMR to SMR, it can correct the positional deviation of the three tracks 11b of the range 60.

[0068] Hereinafter, the storage area that is set as the target of switching the track configuration mode, such as the range 60, will be recorded as the target storage area. Figure 5 and Figure 6 In the description above, the method for selecting the target storage area is described as being free of restrictions. However, restrictions may be placed on the method for selecting the target storage area. For example, the target storage area may be selected in units of areas separated by the guard area 11c. Furthermore, the target storage area may be selected in units of zones, bands, or the like.

[0069] As described above, the post-code area 100 storing the post-code group for CMR and the post-code group for SMR is provided within a predetermined range in the radial direction of the magnetic disk 11. The location of the post-code area 100 is not limited to a specific location. In one example, the post-code area 100 can be provided in the radial center of the magnetic disk 11.

[0070] exist Figure 5 and Figure 6 In the example shown, the post-code area 100 is an example of a first storage area. The CMR area 110a and the SMR area 110b are examples of a second storage area. That is, the first storage area and the second storage area are provided in the radial direction of the magnetic disk 11.

[0071] In addition, Figure 5 and Figure 6 In the example shown, the servo area 11a is an example of the third storage area, and the data area 11d is an example of the fourth storage area. That is, the third storage area and the fourth storage area are provided in the circumferential direction of the magnetic disk 11.

[0072] Next, the positional relationship between the read head 22r and the write head 22w in the radial direction of the magnetic disk 11 will be described. In this specification, the position in the radial direction of the magnetic disk 11 is referred to as a radial position.

[0073] The read head 22r and the write head 22w are actually separated from each other and are provided on the magnetic head 22. Therefore, the radial position of the read head 22r and the radial position of the write head 22w are not necessarily equal to each other. Moreover, the positional relationship between the radial position of the read head 22r and the radial position of the write head 22w varies depending on the position of the magnetic head 22.

[0074] Figure 7 This is a schematic diagram for explaining an example of the positional relationship between the radial position of the read head 22 r and the radial position of the write head 22 w in the magnetic disk device 1 according to the first embodiment.

[0075] according to Figure 7In the example shown, the read head 22r and the write head 22w are arranged in the extending direction of the actuator arm 15. The read head 22r is arranged on the side closer to the rotation axis of the actuator arm 15 than the write head 22w.

[0076] For example, at position P a1 The direction in which the write head 22w and the read head 22r are arranged is perpendicular to the radial direction. In this case, the radial position of the read head 22r and the radial position of the write head 22w are equal to each other.

[0077] When the magnetic head 22 is at position P a1 Area A on the inner side inner In the case of, for example, when the magnetic head 22 is at position P a2 In this case, the write head 22w is located on the inner circumference side of the read head 22r. In other words, the radial position of the write head 22w is farther from the inner circumference side than the radial position of the read head 22r. The distance between the radial position of the write head 22w and the radial position of the read head 22r increases as the position of the magnetic head 22 moves from position P to position P. a1 It becomes larger as it moves away from the inner circumference.

[0078] When the magnetic head 22 is at position P a1 Area A on the outer side outer In the case of, for example, when the magnetic head 22 is at position P a3 In the case of , the write head 22w is located on the outer circumference side of the magnetic disk 11 relative to the read head 22r. In other words, the radial position of the write head 22w is farther away from the radial position of the read head 22r toward the outer circumference. The distance between the radial position of the write head 22w and the radial position of the read head 22r increases as the position of the magnetic head 22 moves from position P to position P. a1 It becomes larger as it moves away from the outer peripheral side.

[0079] Thus, the radial position of the magnetic head 22 and the position P a1 In different cases, the radial position of the write head 22w and the radial position of the read head 22r are separated. In other words, the write head 22w and the read head 22r are located on different tracks 11b.

[0080] Then, the controller 30 writes the post code used to correct the positional offset of the track 11b where the write head 22w is located, to the track 11b where the read head 22r is located. Thus, when writing user data to the magnetic disk 11, the controller 30 can position the write head 22w on the target track 11b while reading the post code used to correct the positional offset of the target track 11b using the read head 22r.

[0081] Hereinafter, in this specification, when a postcode used to correct the positional offset of track #X is written to track #Y, track #Y will be referred to as the code track of track #X. Furthermore, the postcode written to track #Y, i.e., the postcode used to correct the positional offset of track #X, will be referred to as the postcode of track #X.

[0082] Figure 8 This is a schematic diagram for explaining the positional relationship between the track 11b and the code track of the track 11b in the magnetic disk device 1 according to the first embodiment. b1 In this case, the write head 22w is located at the center of track #N, and the read head 22r is located near the center of track #M. Thus, track #M can be set as the code track of track #N.

[0083] When the magnetic head 22 is at position P b2 In this case, the write head 22w is located at the center of track #M. At this time, the controller 30 writes the post code of track #N to track #M using the write head 22w.

[0084] As described above, in the first embodiment, the controller 30 also writes user data as part of formatting when writing the post-code. b2 In this case, the controller 30 writes the post code of track #N to the servo area 11a of track #M, and writes the user data to the data area 11d of track #M.

[0085] Next, the operation of the magnetic disk device 1 according to the first embodiment will be described.

[0086] Figure 9 This is a flowchart showing an example of the operation of the magnetic disk device 1 according to the first embodiment.

[0087] First, the magnetic disk device 1 receives a command requesting a track arrangement switching from the host 40 (S101). In response to the command, the controller 30 reads the postcode group for the track arrangement to be switched from the postcode area 100 and stores it in the buffer memory 29 (S102).

[0088] The command requesting a track configuration switch includes information indicating the range of the target area, that is, the target storage area. In one example, the command can indicate the target storage area by position, size, or a combination thereof. In another example, the command can indicate the target storage area by, for example, a band or zone identifier. In the process of S102, the postcode indicating the target storage area size is read from postcode area 100 and stored in buffer memory 29.

[0089] The processes from S102 to S107 described later are examples of the first process in the first embodiment. In the first process, the controller 30 executes control to read a postamble group from the postamble area 100 and write the read postamble group to the target storage area (more precisely, the servo areas 11a of the plurality of tracks 11b in the target storage area).

[0090] Following S102, the controller 30 selects one track 11b from all tracks 11b in the target storage area as the target track 11b to which the postcode and user data are to be written (S103). The target tracks 11b in the target storage area are all tracks 11b configured according to the track configuration of the switching target. The controller 30 selects one track 11b from the tracks 11b to which the postcode and user data have not yet been written. The track 11b selected in S103 is referred to as the target track. The target track is an example of track 1.

[0091] Next, the controller 30 performs seek control to move the magnetic head 22 toward the track to be written (S104). Then, the controller 30 performs tracking control to maintain the write head 22w on the track to be written (S105). In this tracking control, the controller 30 can use the post code of the track to be written from the post code group stored in the buffer memory 29.

[0092] In addition, when the postcode of the write target track has been written to the code track of the write target track at the time of processing S105, the controller 30 can also obtain the postcode from the code track using the read head 22r and use the obtained postcode in tracking control.

[0093] The controller 30 executes control to write a post-code to the servo area 11a and to write user data to the data area 11d as part of formatting under tracking control (S106). The post-code written in S106 is the post-code of track 11b, which sets the write target track as the code track. The controller 30 writes the post-code when the write head 22w passes through the servo area 11a of the write target track, and writes the user data when the write head 22w passes through the data area 11d of the write target track. The controller 30 writes the post-code to all servo areas 11a of the write target track and writes the user data to all data areas 11d of the write target track.

[0094] The process of writing the postamble into the servo area 11 a in the process of S106 is an example of the second process in the first embodiment. The process of writing the user data into the data area 11 d in the process of S106 is an example of the third process in the first embodiment.

[0095] After the writing of the postcode and the user data to the write target track is completed, the controller 30 determines whether or not there is a track in the target storage area to which the writing of the postcode and the user data has not been completed ( S107 ).

[0096] If a track to which the postcode and user data have not been written is left (S107: YES), control proceeds to S103. If a track to which the postcode and user data have not been written is left (S107: NO), the operation of the first embodiment ends.

[0097] Thus, in the first embodiment, the controller 30 executes a first process of reading a post code group from the post code area 100 and writing the read post code group into the servo area 11a of the target storage area. In the first process, the controller 30 executes control such that the post code is written into the servo area 11a and the user data is written into the data area 11d while the write head 22w is kept on the track to be written under tracking control.

[0098] Thus, in the series of processes related to post-code writing, the number of seek control executions can be reduced compared to the comparative example technique. As a result, the time required for the series of processes related to post-code writing is shortened compared to the comparative example technique. In other words, the efficiency of the processes related to post-code writing is improved.

[0099] (Second embodiment)

[0100] In the first embodiment, the postcode is written when the user data is written as part of the formatting. However, the timing of writing the postcode is not limited to this.

[0101] In the second embodiment, the postcode is written when the magnetic disk 11 is accessed to write or read user data in accordance with an access command from the host 40. The second embodiment will be described below.

[0102] When writing the postcode and reading the user data corresponding to the access command together under tracking control, it is necessary to satisfy the condition that the read head 22r is located on the read target track (read target track) and the write head 22w is located on the write target track. This condition is referred to as the write permission condition.

[0103] Figure 10 This is a schematic diagram for explaining the details of the write permission condition in Embodiment 2. In this figure, for convenience, the radial position of the track center of a certain track #P is assumed to be the origin, and the outward direction is assumed to be the positive direction.

[0104] For example, when write head 22w writes data (referred to as write data D1) to the center of track #P, the width of the range where write data D1 is written is W. To read this write data D1 using read head 22r, the center of read head 22r needs to be located within range A1, which is offset from the left and right ends of the range where write data D1 is written by a predetermined offset E. In other words, range A1 is the range from which write data D1 can be read. When position CR of read head 22r satisfies the following equation (1), write data D can be read.

[0105] -(W / 2-E)≤CR≤(W / 2-E)…(1)

[0106] In contrast, the range A2 read by read head 22r is determined by design. Range A2 is narrower than range A1. To read data within the range of -A2 / 2 to A2 / 2 at read head 22r position CR, the data must be within range A3 of -(W-A2 / 2-R / 2+E) to (W-A2 / 2-R / 2+E). Figure 10 L1 shows the write range of data written at the innermost position within range A3 (referred to as write data D2 ), and L2 shows the write range of data written at the outermost position within range A3 (referred to as write data D3 ).

[0107] In order to make the data writing range fall within the range A3, the position CW of the write head 22w needs to satisfy the following equation (2).

[0108] -(W / 2-A2 / 2-R / 2+E)≤CW≤(W / 2-A2 / 2-R / 2+E)…(2)

[0109] The range in which CW can be taken is recorded as the write permission range. Figure 12 In the example shown, A4 represents the write-enabled range. When the read head 22r is positioned on the read track and the write head 22w is positioned within the write-enabled range of the write track, the controller 30 can perform both reading of user data and writing of the postcode under tracking control. When the position of the write head 22w deviates from the write-enabled range based on the center of the write track while the read head 22r is positioned on the read track, the controller 30 performs reading of user data under tracking control but does not perform writing of the postcode.

[0110] Figure 11 This is a flowchart showing an example of the operation of the magnetic disk device 1 according to the second embodiment.

[0111] First, the magnetic disk device 1 receives a command requesting a track arrangement switching from the host 40 (S201). In response to the command, the controller 30 reads the postcode group for the track arrangement to be switched from the postcode area 100 and stores it in the buffer memory 29 (S202).

[0112] In the second embodiment, S202 to S204 and S206 to S214 correspond to an example of the first process.

[0113] Thereafter, the magnetic disk device 1 can execute post-code writing in response to receipt of an access command. Specifically, when the magnetic disk device 1 receives an access command from the host 40 (S203), the controller 30 determines whether the access target corresponding to the access command is a track within the target storage area (S204). If the access target corresponding to the access command is not a track within the target storage area (S204: No), the controller 30 executes the access command (S205), and control proceeds to S203.

[0114] When the access target corresponding to the access command is a track in the target storage area ( S204 : YES), the controller 30 determines whether the received access command is a write command ( S206 ).

[0115] If the received access command is a write command (S206: Yes), the controller 30 performs seek control to move the magnetic head 22 toward the track 11b (referred to as the write target track) to which the user data to be written by the write command is to be written (S207). The controller 30 then performs tracking control to maintain the write head 22w on the write target track (S208). In this tracking control, the controller 30 can use the postcode of the write target track from the postcode group stored in the buffer memory 29.

[0116] In addition, when the postcode of the write target track has been written to the code track of the write target track at the time of processing S208, the controller 30 can also obtain the postcode from the code track using the read head 22r and use the obtained postcode in tracking control.

[0117] The controller 30 executes control to write the post-code to the servo area 11a and the user data in accordance with the write command to the data area 11d under tracking control (S209). The post-code written in S209 is the post-code of track 11b, which sets the write target track as the code track. The controller 30 writes the post-code when the write head 22w passes through the servo area 11a of the write target track, and writes the user data when the write head 22w passes through the data area 11d of the write target track. The controller 30 writes the post-code to all servo areas 11a of the write target track. The user data requested by the write command is written to the data area 11d of the write target track.

[0118] Furthermore, if a postcode has already been written to the write target track, the controller 30 may control the writing of user data without writing the postcode in S209. This prevents the same postcode from being written multiple times to the same track 11b.

[0119] Next, the controller 30 determines whether any tracks to which the postcode and user data have not been written remain in the target storage area (S210). If any tracks to which the postcode and user data have not been written remain (S210: Yes), control proceeds to S203. If no tracks to which the postcode and user data have not been written remain (S210: Yes), the controller 30 terminates the series of operations.

[0120] If the received access command is not a write command (S205: No), that is, if the received access command is a read command, the controller 30 executes seek control to move the magnetic head 22 toward the track 11b (referred to as the read target track) storing the user data requested to be read by the read command (S211). Then, the controller 30 executes tracking control to maintain the read head 22r on the read target track (S212).

[0121] Under tracking control in S212, the controller 30 determines whether the write head 22w is within the write-permitted range of another track 11b (S213). If the write head 22w is within the write-permitted range (S213: Yes), the controller 30 executes control to write the post code of the track 11b where the write head 22w is located to the servo area 11a and read the user data from the data area 11d of the read target track (S214). Then, control returns to S210.

[0122] Furthermore, if a postcode has already been written to the write target track, the controller 30 may control the reading of user data without writing the postcode in S214. This prevents the same postcode from being written multiple times to the same track 11b.

[0123] If the write head 22w is not located within the write permission range (S213: No), the controller 30 executes control to read user data from the data area 11d of the read target track (S215). Then, the control returns to S210.

[0124] Furthermore, the process of writing the post-code into the servo area 11a in S209 and the process of writing the post-code into the servo area 11a in S214 are examples of the second process in the second embodiment. The process of writing the user data into the data area 11d in S209 and the process of reading the user data from the data area 11d in S214 are examples of the third process in the second embodiment.

[0125] Thus, according to the second embodiment, in the first process, the controller 30 performs the following control: under tracking control to maintain the write head 22w on the write target track, the post-code is written to the servo area 11a and the user data is written to the data area 11d or the user data is read from the data area 11d.

[0126] Thus, since the post-code is written in parallel with the writing or reading of the user data, the efficiency of the process related to the post-code writing is improved compared to the technique of the comparative example.

[0127] According to the second embodiment, the magnetic disk device 1 performs the following characteristic operation in response to an access command, which is a command for writing or reading user data. Specifically, when the magnetic disk device 1 receives an access command from the host computer 40, the controller 30 controls the magnetic disk 11 to access the magnetic disk 11 in accordance with the access command, while the magnetic head 22 is positioned relative to the magnetic disk 11. Consequently, the postcode of the track 11b where the write head 22w is located, while the magnetic head 22 is positioned relative to the magnetic disk 11, differs before and after the access.

[0128] (Third embodiment)

[0129] In the first and second embodiments, the controller 30 writes the post-code read from the post-code area 100 into the servo area 11a of the track 11b in the target storage area. Alternatively, the controller 30 may perform a predetermined calculation on the post-code read from the post-code area 100 and write the calculated post-code into the servo area 11a of the track 11b in the target storage area.

[0130] In the third embodiment, the controller 30 executes post-code correction as an example of computational processing. Specifically, when writing the post-code of track #U to the code track of track #U, the controller 30 corrects the post-code of track #U read from the post-code area 100 based on the positional offset of track 11b, namely, track #U-1, adjacent to track #U. The controller 30 then writes the corrected post-code of track #U to the code track of track #U.

[0131] In recent years, there has been a trend toward narrowing the spacing between tracks 11b to increase recording density. Furthermore, the spacing between tracks 11b, defined by servo information, can fluctuate in the radial and circumferential directions, depending on factors such as the accuracy of writing the servo information. This can lead to situations where two adjacent tracks 11b become too close to each other. In such cases, reading data written in these close proximity can become difficult.

[0132] In the third embodiment, each post code is corrected based on the positional offset between adjacent tracks, thereby preventing data reading from becoming difficult due to the tracks 11b being too close to each other.

[0133] Hereinafter, the post-code read from the post-code area 100 and before being corrected will be recorded as the original post-code.

[0134] Figure 12 This is a schematic diagram for explaining the post-code correction process according to the third embodiment. This diagram will be used to explain the process of correcting the post-code of track #U.

[0135] Before writing the postcode of track #U to the target storage area, the controller 30 learns the RRO of track #U-1 as the position offset of track #U-1. Learning the RRO can also be referred to as measuring the RRO or detecting the RRO. The controller 30 detects the actual position of track #U-1 using the read head 22r and acquires the detected position as the RRO of track #U-1.

[0136] Figure 12 (A) is a coordinate diagram showing the measured position of track #U-1, i.e., the RRO of track #U-1 obtained through learning. The horizontal axis represents the circumferential position of one cycle. Figure 12 (A)~(E) are all connected.

[0137] The controller 30 generates a post code for track #U-1 based on the measured RRO of track #U-1.

[0138] Figure 12(B) is a coordinate diagram showing the post-code generated based on the measured RRO of track #U-1. As can be seen from this diagram, the post-code for track #U-1 is generated by inverting the sign of the RRO of track #U-1. The method for generating the post-code for track #U-1 is not limited to this.

[0139] The controller 30 uses the generated post-code of track #U-1 to correct the original post-code of track #U.

[0140] Figure 12 (C) is a coordinate diagram showing an example of the original post-code of track #U. Figure 12 (D) is a coordinate diagram showing an example of the post-code of track #U after correction. Figure 12 In the examples shown in (B), (C), and (D), the modified post-code of track #U is obtained by adding the post-code of track #U-1 and the original post-code of track #U.

[0141] Figure 12 (E) shows the use of Figure 12 (D) shows an example of a coordinate diagram of the position of Track #U after the positional deviation is corrected by the corrected post-code of Track #U. As shown in this figure, it can be understood that the correction based on the corrected post-code of Track #U brings the actual Track #U closer to the ideal Track #U.

[0142] In addition, when using Figure 12 In the example described, the postcode is corrected by simple addition. The correction operation is not limited to simple addition. For example, the controller 30 can obtain the corrected postcode of track #U by weighted addition as shown in the following equation (3).

[0143] PC U _cor=(k*PC U-1 +(1-k)*PC U _org) / 2…(3)

[0144] Among them, PC U-1 Indicates the post-code of the generated track #U-1. PC U _org indicates the original post-code of track #U. PC U _cor represents the post-code of the corrected track #U. k is a set value of a real number between 0 and 1.

[0145] The controller 30 can execute the RRO used in the correction at any timing (in Figure 12 The example is the learning of the RRO of track #U-1.

[0146] In one example, the controller 30 may also perform seek control and track control only for the purpose of learning RRO. Figure 12 In the example, the magnetic head 22 may be moved toward the track #U-1 and the read head 22r may be maintained on the track #U-1 for the purpose of learning the RRO of the track #U-1 only.

[0147] In another example, the controller 30 may execute RRO learning in parallel with writing of user data or postcode when the write head 22w is located on the track 11b to be learned during writing of user data or postcode.

[0148] Figure 13 This is a diagram for explaining the conditions for executing RRO learning in parallel with writing in the magnetic disk device 1 according to the third embodiment. This condition is referred to as a learning permission condition.

[0149] exist Figure 13 In the example shown, tracking control of the magnetic head 22 is performed so that the write head 22w is positioned at the center of track #Q in order to write a postcode or user data to track #Q. While the write head 22w is positioned at the center of track #Q, the read head 22r is positioned on track #R, which is different from track #Q. At this point, if the read head 22r is within the write-enabled range, the controller 30 can learn the RRO of track #R. Specifically, the learning-enabled condition is that the read head 22r is within the write-enabled range of the target track 11b.

[0150] For example, when writing user data or a postcode, if the read head 22r is within the write-allowed range of any track 11b in the target storage area, the controller 30 can perform RRO learning in parallel with the writing of the user data or the postcode. When writing user data or a postcode, if the read head 22r is not within the write-allowed range of all tracks 11b in the target storage area, the controller 30 does not perform RRO learning in parallel with the writing of the user data or the postcode.

[0151] Figure 14 This is a flowchart showing an example of the operation of the magnetic disk device 1 according to the third embodiment. Here, the operation of writing the postcode of one track #S will be described.

[0152] First, the controller 30 performs learning of the RRO of track #S-1 using the read head 22r (S301).

[0153] When the third embodiment is used in conjunction with the first embodiment, the controller 30 can be used Figure 9 The process of S301 is executed at any timing in the first process described.

[0154] The postcode written to the write target track is a postcode that sets the write target track as the code track. Figure 14 In the description of , it can be considered as the postcode of track #S. After selecting the write target track through the process of S103, the controller 30 can also execute the process of S301 by setting the track adjacent to the track where the write target track is set as the code track as the learning target.

[0155] Alternatively, the controller 30 may learn the RRO for all tracks 11b in the target storage area, i.e., perform the process of S301. The controller 30 may store the learned RRO in the buffer memory 29 or RAM 27 until correction is required. The controller 30 may generate a post-code based on the learned RRO through the process of S302 described later, and store the generated post-code in the buffer memory 29 or RAM 27. The controller 30 may also modify the original post-code in the buffer memory 29 through the process of S303 described later, based on the generated post-code, and overwrite the original post-code with the modified post-code.

[0156] Alternatively, the controller 30 may learn the RRO of the track 11b where the write head 22w is located if the learning permission conditions are met during S105-S106. The controller 30 may store the learned RRO in the buffer memory 29 or RAM 27 until correction is required. The controller 30 may generate a post-code based on the learned RRO in the process of S302 and store the generated post-code in the buffer memory 29 or RAM 27. The controller 30 may also correct the original post-code in the buffer memory 29 based on the generated post-code in the process of S303, overwriting the original post-code with the corrected post-code.

[0157] When the third embodiment is used in conjunction with the second embodiment, the controller 30 can be used Figure 11 The process of S301 is executed at any timing in the first process described.

[0158] For example, RRO learning, i.e., the process of S301, may be performed for all tracks 11b in the target storage area. The controller 30 may store the learned RRO in the buffer memory 29 or RAM 27 until correction is required. The controller 30 may generate a post-code based on the learned RRO through the process of S302 and store the generated post-code in the buffer memory 29 or RAM 27. The controller 30 may also correct the original post-code in the buffer memory 29 based on the generated post-code through the process of S303, overwriting the original post-code with the corrected post-code.

[0159] Alternatively, if the learning permission conditions are met during S208-S209, the RRO of the track 11b where the write head 22w is located may be learned. The controller 30 may store the learned RRO in the buffer memory 29 or RAM 27 until correction is required. The controller 30 may generate a post-code based on the learned RRO in the process of S302 and store the generated post-code in the buffer memory 29 or RAM 27. The controller 30 may also correct the original post-code in the buffer memory 29 based on the generated post-code in the process of S303, overwriting the original post-code with the corrected post-code.

[0160] Following S301, the controller 30 generates a post-code of track #S-1 based on the learned RRO of track #S-1 (S302).

[0161] Then, the controller 30 corrects the original post-code of track #S based on the post-code of track #S-1 (S303).

[0162] Then, the controller 30 writes the corrected post-code of track #S into the servo area 11a of the code track of track #S (S304). Then, a series of operations of the magnetic disk device 1 according to the third embodiment are completed.

[0163] When the third embodiment is used in combination with the first embodiment, the process of S304 is Figure 9 In the case where the third embodiment is used together with the second embodiment, the processing of S304 is performed in Figure 11 The process is executed in S209 or S214 in the series of operations shown.

[0164] Thus, in the third embodiment, in the first process, the controller 30 obtains the positional offset between adjacent tracks, corrects the post-code based on the obtained positional offset, and then writes the corrected post-code into the servo area 11a of the write target track.

[0165] This can prevent data reading from becoming difficult due to the tracks 11b being too close to each other.

[0166] Furthermore, when writing the post-amble, the magnetic disk device 1 may be affected by temperature or vibration. These effects may differ for each magnetic disk device 1. Furthermore, there are cases where these effects cause the position of the tracks 11b to shift, causing the tracks 11b to be too close to each other.

[0167] In the third embodiment, since the magnetic disk device 1 is configured as described above, it is possible to prevent the tracks 11b from coming too close to each other due to the influence of temperature or vibration.

[0168] Furthermore, according to the third embodiment, the controller 30 generates a post code for the adjacent track based on the acquired positional deviation amount of the adjacent track, and corrects the post code written to the write target track based on the post code for the adjacent track.

[0169] More specifically, in one example, the controller 30 corrects the post-code written to the write-target track by weighted addition of the post-code written to the write-target track and the post-codes of adjacent tracks.

[0170] In the first to third embodiments, the controller 30 executes the first process upon receipt of a command requesting a track configuration switch. The execution of the first process is not limited to receipt of a command requesting a track configuration switch. The controller 30 may also execute the first process upon receipt of any event.

[0171] As described in the first to third embodiments, the controller 30 executes a first process of reading a post-code group from the post-code area 100 and writing the read post-code group to the servo area 11a of the target storage area. In the first process, the controller 30 performs control such that the post-code is written to the servo area 11a and the user data is written to or read from the data area 11d, while the write head 22w is kept on the track to be written.

[0172] This improves the efficiency of the process related to writing the post-code.

[0173] While some embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention and are included in the invention described in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: A magnetic disk having a first storage area and a second storage area in which a plurality of tracks are set in a radial direction, wherein the first storage area stores a plurality of post codes for correcting positional deviations of the plurality of tracks, and the second storage area having a third storage area and a fourth storage area in a circumferential direction; a magnetic head including a write head for writing to the magnetic disk and a read head for reading from the magnetic disk; and The controller performs the following control: executing a first process of reading the plurality of post-codes from the first storage area and writing the plurality of post-codes read out to the third storage area of ​​the second storage area; in the first process, with the write head positioned on the first track of the plurality of tracks, executing both a second process of writing the first post-code among the plurality of post-codes read out to the third storage area and a third process of writing user data to or reading user data from the fourth storage area; The first post-code is a post-code for correcting a positional deviation of the second track.

2. The magnetic disk device according to claim 1, The second track is a track where the write head is located when the read head is located on the first track.

3. The magnetic disk device according to claim 2, The controller performs the following control: In the first process, a positional offset of a third track adjacent to the second track among the plurality of tracks is obtained, and the first postcode is corrected based on the positional offset of the third track. In the second process, the corrected first postcode is written.

4. The magnetic disk device according to claim 3, the controller, generating a second postcode for correcting the positional deviation of the third track based on the obtained positional deviation of the third track, The first post-code is modified by weighted addition of the first post-code and the generated second post-code.

5. The magnetic disk device according to any one of claims 1 to 4, The configuration of the plurality of tracks in the second storage area is configured to be switchable between two configurations. The plurality of post-codes include two groups of post-codes corresponding to different modes among the two modes, The controller performs control such that, in the first process, the group corresponding to the switching destination mode among the two groups is read from the first storage area, and the plurality of post codes included in the read group is written into the third storage area of ​​the second storage area.

6. The magnetic disk device according to claim 5, One of the two methods is to arrange the plurality of tracks so that data of one of two tracks adjacent to each other in the radial direction of the disk is written to overlap with a portion of data of the other of the two tracks. The other of the two methods is a method in which the plurality of tracks are arranged so that data of two tracks adjacent to each other in the radial direction of the magnetic disk do not overlap with each other.

7. A magnetic disk device comprising: A magnetic disk having a plurality of tracks arranged in a radial direction; a magnetic head including a write head for writing to the magnetic disk and a read head for reading from the magnetic disk; and The controller performs the following control: accessing the magnetic disk in a first state where the magnetic head is positioned according to a write command or a read command from a host, Among the plurality of tracks, a first track, which is a track where the write head is located in the first state, has a post code that is different before and after the access.

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