Magnetic disk device and control method thereof

Abstract

To provide a magnetic disk device with high reliability that can eliminate problems of auxiliary second data writing being stopped midway, thereby preventing a decline in data writing performance, and a control method thereof.SOLUTION: A magnetic disk device includes: first write control to write first data and second data to a magnetic disk; and a second write control to write the first data to the magnetic disk, wherein a time required from the start of processing the first write control to the completion of the processing is predicted upon receiving a write command, and either the processing of the first write control or the processing of the second write control is selectively executed by comparing the predicted time with a preliminarily designated limited time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments relate to a magnetic disk device including a magnetic disk and a magnetic head, and a method for controlling the magnetic disk device. [Background technology]

[0002] A magnetic disk device equipped with a magnetic disk and a magnetic head writes and reads data to and from the magnetic disk in response to write and read commands sent from an external host device (host computer). When a latency limit that limits the delay in writing data is specified by a host device, the magnetic disk device executes the data writing process within the time limit of the latency limit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,872,800 [Patent Document 2] U.S. Patent No. 1,1294,767 [Patent Document 3] U.S. Patent No. 5,720,025 [Patent Document 4] U.S. Patent No. 5,583,876 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to the user data (first data), the data written to the magnetic disk includes auxiliary second data such as error correction codes (ECC) for the user data and log data related to the writing of the user data. If the latency limit expires while writing this second data, the magnetic disk drive must stop writing the second data. In this case, the magnetic disk drive must suddenly take steps to forcibly write the second data that could not be written, and the sudden execution of this step degrades the performance of subsequent data writes. This performance degradation leads to delays in data writes.

[0005] The purpose of the embodiment is to provide a highly reliable magnetic disk device and a control method thereof that can eliminate the problem of auxiliary second data writing being stopped midway, thereby preventing a decrease in data writing performance. [Means for solving the problem]

[0006] A magnetic disk drive according to an embodiment includes a circular magnetic disk including a plurality of data recording tracks, each consisting of a plurality of sectors aligned in a circumferential direction, aligned along a radial direction; a magnetic head arranged to be able to seek in the radial direction of the magnetic disk and to write and read data to and from the magnetic disk; and a controller for controlling the rotation of the magnetic disk and the seeking of the magnetic head. The controller further includes a first write control means for writing first data and second data to each sector of a predetermined track among the tracks; a second write control means for writing the first data to each sector of a predetermined track among the tracks; and a selection control means for predicting, upon receiving a write command, the time required from the start to the end of processing by the first write control means, and selectively executing either the processing by the first write control means or the processing by the second write control means by comparing the predicted time with a predetermined time limit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the overall configuration of each embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a main part of a magnetic disk in each embodiment. [Figure 3] FIG. 3 is a diagram showing one track and a plurality of sectors of a magnetic disk in the first embodiment. [Figure 4] FIG. 4 is a diagram showing a data write range for each sector in FIG. [Figure 5] 5 is a diagram showing the data read range for each sector in FIG. 4 and showing how data in unreadable sectors is rescued using error correction codes. [Figure 6] FIG. 6 is a diagram showing the latency limit time (ti+ta) in each embodiment. [Figure 7] FIG. 7 is a diagram showing an example in which the end timing of the time limit ta arrives during the data write process in each embodiment. [Figure 8] FIG. 8 is a flowchart showing the control of each embodiment. [Figure 9] FIG. 9 is a diagram showing the relationship between the predicted time tx and the time limit ta in the first embodiment. [Figure 10] FIG. 10 is a diagram showing one track and a plurality of sectors of a magnetic disk in the second embodiment. [Figure 11] FIG. 11 is a diagram showing the relationship between the predicted time tx and the time limit ta in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [1] First embodiment The first embodiment will be described below with reference to the drawings. 1, a magnetic disk device 1 includes a magnetic disk 2, which is a recording medium, a spindle motor 3 that rotates the magnetic disk 2, and a magnetic head 10 that writes and reads data to and from the magnetic disk 2. An actuator 20 that supports the magnetic head 10 is disposed near the magnetic disk 2.

[0009] The actuator 20 supports the magnetic head 10 so that it can seek in the radial direction of the magnetic disk 2. That is, the actuator 20 is also called an actuator block or a head stack assembly (HSA), and includes a rotating shaft 21, an arm 22 whose midsection is held by the rotating shaft 21, a voice coil motor (VCM) 23 provided at the base end of the arm 22, and a suspension member 24 provided at the tip of the arm 23 to hold the magnetic head 10. When a driving current is supplied to the voice coil motor 23, the magnetic head 10 is rotated from a first position P1 indicated by a dashed line to a second position P2 indicated by a solid line. With this rotation, the magnetic head 10 seeks (moves) in the radial direction of the magnetic disk 2 along a locus T shown in the figure.

[0010] A stopper ST and a ramp mechanism RL are disposed near the actuator 20. The stopper ST limits the movement position of the magnetic head 16 on the inner periphery side of the magnetic disk 12. The ramp mechanism RL limits the movement position of the magnetic head 16 on the outer periphery side of the magnetic disk 12.

[0011] The magnetic disk device 1 includes a controller 30 which is the center of control, a head amplifier 41 which drives the magnetic head 10, a signal processing circuit 42 which is provided between the connection between this head amplifier 41 and the controller 30, a motor driver 43 which is provided between the connection between the voice coil motor 23 and the controller 30, a DRAM 44 which is a memory which stores programs etc. necessary for controlling the controller 30, a flash ROM 45 which is a memory which stores various data necessary for controlling the controller 30, and a hard disk controller (HDC) 46 which is provided between the connection between the controller 30, the hard disk controller (HDC), and an external host device (host computer) 50.

[0012] The head amplifier 41 amplifies a write data signal sent from the signal processing circuit 42 to the magnetic head 10, and also amplifies a data signal read by the magnetic head 10. The signal processing circuit 42 appropriately processes a write data signal sent from the controller 30 to the magnetic head 10 and supplies it to the head amplifier 41, and also appropriately processes a read data signal amplified by the head amplifier 41 and supplies it to the controller 30. The motor driver 43 controls the drive current for the spindle motor 3 and the drive current for the voice coil motor 23 of the actuator 20 in accordance with instructions from the controller 30.

[0013] As shown in Fig. 2, the magnetic disk 2 has a circular shape and is coaxially fitted to the rotation shaft of the spindle motor 3, and includes a plurality of tracks Tr for recording data formed side by side along the radial direction. As shown in Fig. 3, each track Tr includes a plurality of first sectors S1, S2, ... Sn aligned in the circumferential direction of the magnetic disk 2 and at least one second sector Sp following the end of the alignment of these first sectors S1, S2, ... Sn.

[0014] The first sectors S1, S2, ... Sn are used to record main first data, such as user data used by the user of the magnetic disk device 1. The second sectors Sp are used to record auxiliary second data related to the user data, such as track ECC (Error-Correcting Code). The track ECC is an error-correcting code that detects and corrects errors in the user data for each track Tr.

[0015] The controller 30 includes, as its main functions, a position acquisition section (position acquisition means) 30a, a seek control section (seek control means) 30b, a settling determination section (determination means) 30c, a first write control section (first write control means) 30d, a second write control section (second write control means) 30e, and a selection control section (selection control means) 30f.

[0016] [Location Acquisition Section 30a] The position capture section 30 a captures the position of the magnetic head 10 on the magnetic disk 2 based on the position data of the servo pattern SB included in the read data of the magnetic head 10 .

[0017] [Seek Control Section 30b] The seek control section 30b controls the drive (drive current) of the voice coil motor 23 of the actuator 20, thereby causing the magnetic head 10 to seek from the stop position to the target position on the magnetic disk 2. Specifically, the seek control section 30b controls the drive (drive current) of the voice coil motor 23 of the actuator 20 based on the capture position of the position capture section 30a, thereby causing the magnetic head 10 to seek from the stop position to the target position on the magnetic disk 2, sequentially accelerating and decelerating.

[0018] [Settling Determination Section 30c] The settling determination section 30c performs a so-called settling determination, which determines that the magnetic head 10 has reached the target position when a certain period of time has passed while the capture position of the position capture section 30a remains within a specified range that includes the target position.

[0019] [First Write Control Section 30d] The first write control section 30d causes the magnetic head 10 to seek to a predetermined track Tr among the tracks Tr of the magnetic disk 2 through the control of the seek control section 30b, and writes user data (first data) to a predetermined number of first sectors from the beginning of the first sectors S1, S2, ... Sn on the predetermined track Tr as the magnetic disk 2 rotates, and after writing of this user data is completed, writes track ECC (second data) to a second sector Sp of the predetermined track Tr as the magnetic disk 2 rotates, and after writing of this track ECC is completed, notifies the host device 50, which is the sender of the write command, of the completion of processing (status response code).

[0020] 4, for example, user data is written to three first sectors S1, S2, and S3, and after the user data has been written, a track ECC is written to the last second sector Sp as the magnetic disk 2 rotates (after a predetermined rotational wait period). The track ECC period is the sum of the rotational wait period and the period for writing the track ECC to the second sector Sp.

[0021] By writing the track ECC, even if data cannot be read from the first sector S3 shown by the diagonal lines in Figure 5, an error in the data in the first sector S3 can be detected and corrected by the track ECC of the second sector Sp. In other words, the data in the first sector S3 is saved by the track ECC.

[0022] [Second Write Control Section 30e] The second write control section 30e causes the magnetic head 10 to seek a predetermined track Tr among the tracks Tr of the magnetic disk 2 through the control of the seek control section 30b, and as the magnetic disk 2 rotates, writes user data (first data) to a predetermined number of first sectors from the beginning of the first sectors S1, S2, ... Sn on the predetermined track Tr, and after writing of this user data is completed, notifies the host device 50, which is the sender of the write command, of the completion of processing (status response code).

[0023] [Selection Control Section 30f] When the selection control section 30f receives a write command from the external host device 50, it predicts the time tx required from the start of processing (start of seek) of the first write control section 30d to the end of processing (completion of sending of the write command), and selectively executes either the processing of the first write control section 30d or the processing of the second write control section 30e by comparing the predicted time tx with a pre-specified time limit ta.

[0024] Specifically, the selection control section 30f executes the processing of the first write control section 30d if the predicted time tx is equal to or shorter than the time limit ta, and executes the processing of the second write control section 30e if the predicted time tx is longer than the time limit ta.

[0025] The time limit ti is one element of the latency limit (ti+ta) specified by the CDL (1 Command Duration Limits) function of the host device 50, and is an inactive time limit that limits the write preparation time, including predetermined pre-processing, from the reception of a write command to just before disk access (just before seek), as shown in Fig. 6. The write preparation time is set to a state that fits well within this time limit ti.

[0026] The time limit ta is one element of the latency limit time limit (ti+ta) specified by the CDL function of the host device 50, and as shown in Figure 6, it is the active time limit that limits the write execution time including "seek of magnetic head 10," "user data write," "track ECC," and "status response" from the start of disk access (start of seek) to the sending of the status response code.

[0027] A code specifying the time limits ti and ta is included in the write command sent from the host device 50 to the magnetic disk device 1. By specifying the time limit ta, the host device 50 forces the magnetic disk device 1 to execute the data write process corresponding to one write command within the time limit ta.

[0028] If the host device 50 attempts to use the track ECC function in addition to the CDL function, as shown in FIG. 7, the end of the latency limit time ta may occur while the track ECC is being written to the last second sector Sp.

[0029] If the latency limit time ta expires while writing the track ECC, the controller 30 must stop writing the track ECC. In this case, the magnetic disk drive 1 must suddenly take steps to forcibly write the track ECC that could not be written, and the sudden execution of this step reduces the performance of subsequent data writes. This performance degradation leads to delays in data writes.

[0030] The controller 30 executes the control shown in the flowchart of FIG. 8 to prevent this problem from occurring. That is, when the controller 30 receives a write command from the host device 50 (ST1), it predicts the time tx required from the start of processing (start of seek) of the first write control section 30d to the end of processing (completion of sending of the write command) (ST2).

[0031] Specifically, the controller 30 calculates the write execution time, including "seek of magnetic head 10," "user data writing," "track ECC," and "status response," from the start of disk access (seek start) to the sending of the status response code, based on control data previously stored in the internal memory or by calculation, and predicts the calculated write execution time as the time tx required from the start of processing by the first write control section 30d to the end of processing (ST2).

[0032] Then, the controller 30 compares this predicted time tx with the time limit ta specified by the CDL function of the host device 50 (ST3).

[0033] 9 is specified by the host device 50 as the time limit ta, and if the predicted time tx is equal to or shorter than the time limit ta (YES in ST3), the controller 30 causes the magnetic head 10 to seek a predetermined track Tr among the tracks Tr on the magnetic disk 2 (ST4). As the magnetic disk 2 rotates, the controller 30 writes user data to a predetermined number of first sectors S1, S2, ..., Sn on the predetermined track Tr, starting from the beginning (ST5). After writing the user data, the controller 30 waits for the magnetic disk 2 to rotate for a predetermined period during which no user data is written (ST6). Then, when the position of the second sector Sp on the predetermined track Tr corresponds to the magnetic head 10, the controller 30 writes a track ECC (second data) to the second sector Sp (ST7). After writing the track ECC, the controller 30 sends a status response code indicating the completion of processing to the host device 50, which is the sender of the write command (ST8).

[0034] Upon receiving the status response code, the host device 50 executes the process of sending the next write command to the controller 30 .

[0035] 9 is specified by the host device 50 as the time limit ta, and if the predicted time tx is longer than the time limit ta (NO in ST3), the controller 30 causes the magnetic head 10 to seek to a predetermined track Tr among the tracks Tr of the magnetic disk 2 (ST9), and writes user data to a predetermined number of first sectors S1, S2, ... Sn from the beginning of the predetermined track Tr as the magnetic disk 2 rotates (ST10). After writing this user data is complete, the controller 30 sends a status response code indicating the completion of processing to the host device 50, which is the sender of the write command (ST8).

[0036] Upon receiving the status response code, the host device 50 executes the process of sending the next write command to the controller 30 .

[0037] As described above, the time tx from when a write command is received until "writing user data," "writing track ECC," and "status response" are completed is predicted, and if the predicted time tx does not exceed the latency limit time ta specified by the CDL function of the host device 50, the series of processes consisting of "writing user data," "writing track ECC," and "status response" are executed to the end, so that the track ECC can be written to the second sector Sp without violating the latency limit.

[0038] If the predicted time tx exceeds the latency limit time ta, only the user data is written and a status response is sent without writing the track ECC, thereby eliminating the problem of the track ECC writing stopping midway.

[0039] If the track ECC is not written, it will be impossible to correct errors in the written user data. Taking this into consideration, the controller 30 selects an appropriate timing for writing the track ECC (unwritten track ECC) so that the performance of subsequent data writing will not be degraded. In this case, the controller 30 recognizes in advance that the track ECC will not be written, rather than suddenly, and therefore can accurately select an appropriate timing with sufficient leeway so that the performance of data writing will not be degraded. Then, the controller 30 writes the unwritten track ECC to the magnetic disk 2 at the selected timing.

[0040] Since the track ECC is written at an appropriate timing that does not degrade data write performance, it is possible to avoid unnecessary delays in subsequent data writes, thereby improving the reliability of data recording while avoiding violations of latency limits.

[0041] [2] Second embodiment A second embodiment will be described. 10, each track Tr of the magnetic disk 2 includes a plurality of first sectors S1, S2, ... Sn aligned in the circumferential direction of the magnetic disk 2 and at least one second sector Slog following the end of the array of first sectors S1, S2, ... Sn. The first sectors S1, S2, ... Sn are used to record user data (first data) as in the first embodiment. The second sector Slog is used to record auxiliary log data (second data) related to writing user data to the first sectors S1, S2, ... Sn.

[0042] Accordingly, the function of the first write control section 30d of the controller 30 differs from that of the first embodiment. That is, in response to a write command from the host device 50, the first write control section 30d causes the magnetic head 10 to seek to a predetermined track Tr among the tracks Tr of the magnetic disk 2 through the control of the seek control section 30b, and as the magnetic disk 2 rotates, writes user data (first data) to a predetermined number of first sectors from the beginning among the first sectors S1, S2, ... Sn on the predetermined track Tr, and after writing of this user data is completed, writes log data (second data) to a second sector Sp of the predetermined track Tr as the magnetic disk 2 rotates, and after writing of this log data is completed, notifies the host device 50, which is the sender of the write command, of the completion of processing (status response code).

[0043] Of the controls executed by the controller 30, the processes of steps ST2 and ST3 in the flowchart of FIG. 8 are different from those in the first embodiment.

[0044] That is, the controller 30 calculates the write execution time, including "seek of magnetic head 10," "user data write," "log data," and "status response," from the start of disk access (start of seek) to the transmission of the status response code, based on control data stored in advance in an internal memory or by calculation, and predicts the calculated execution time as the time tx required from the start of processing by the first write control section 30d to the end of processing (ST2). Then, the controller 30 compares this predicted time tx with the time limit ta specified by the CDL function of the host device 50 (ST3).

[0045] 11 is specified by the host device 50 as the time limit ta, and if the predicted time tx is equal to or shorter than the time limit ta (YES in ST3), the controller 30 causes the magnetic head 10 to seek a predetermined track Tr among the tracks Tr of the magnetic disk 2 (ST4). As the magnetic disk 2 rotates, the controller 30 writes user data to a predetermined number of first sectors S1, S2, ..., Sn on the predetermined track Tr, starting from the beginning (ST5). After writing the user data, the controller 30 waits for the magnetic disk 2 to rotate for a predetermined period during which no user data is written (ST6). Then, when the position of the second sector Sp on the predetermined track Tr corresponds to the magnetic head 10, the controller 30 writes log data to the second sector Sp (ST7). After writing the track ECC, the controller 30 sends a status response code indicating the completion of processing to the host device 50, which is the sender of the write command (ST8).

[0046] Upon receiving the status response code, the host device 50 executes the process of sending the next write command to the controller 30 .

[0047] 11 is specified by the host device 50 as the time limit ta, and if the predicted time tx is longer than the time limit ta (NO in ST3), the controller 30 causes the magnetic head 10 to seek to a predetermined track Tr among the tracks Tr of the magnetic disk 2 (ST9), and writes user data to a predetermined number of first sectors S1, S2, ... Sn from the beginning of the predetermined track Tr as the magnetic disk 2 rotates (ST10). After writing this user data is complete, the controller 30 sends a status response code indicating the completion of processing to the host device 50, which is the sender of the write command (ST8).

[0048] Upon receiving the status response code, the host device 50 executes the process of sending the next write command to the controller 30 .

[0049] As described above, the time tx from when a write command is received until "writing user data," "writing log data," and "status response" are completed is predicted, and if the predicted time tx does not exceed the latency limit time ta specified by the CDL function of the host device 50, the series of processes consisting of "writing user data," "writing log data," and "status response" are executed to the end, so that the log data can be written to the second sector Slog without violating the latency limit.

[0050] If the predicted time tx exceeds the latency limit time ta, only the user data is written and a status response is sent without writing the log data, thereby eliminating the problem of the log data writing stopping midway.

[0051] If the log data remains unwritten, it will be impossible to check the log related to the written user data. Taking this into consideration, the controller 30 selects an appropriate timing for writing the log data (unwritten log data) so that the performance of subsequent data writing will not be degraded. In this case, the controller 30 recognizes in advance that the track ECC will not be written, rather than suddenly, and therefore can accurately select an appropriate timing with sufficient leeway so that the performance of data writing will not be degraded. Then, the controller 30 writes the unwritten log data to the magnetic disk 2 at the selected timing.

[0052] Since the log data is written at an appropriate timing that does not degrade the performance of data writing, it is possible to avoid the problem of unnecessary delays in subsequent data writing, thereby improving the reliability of data recording while avoiding violations of latency limits. Other configurations and controls are the same as those in the first embodiment.

[0053] [Variations] The above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0054] 1...magnetic disk device, 2...magnetic disk, 10...magnetic head, 20...actuator, 30...controller, 30a...position acquisition section, 30b...seek control section, 30c...settling determination section, 30d...first write control section, 30e...second write control section, 30f...selection control section.

Claims

1. a circular magnetic disk including a plurality of data recording tracks each consisting of a plurality of sectors aligned in a circumferential direction, the tracks being aligned in a radial direction; a magnetic head that is provided to be able to seek in the radial direction of the magnetic disk and that writes and reads data to and from the magnetic disk; a controller that controls the rotation of the magnetic disk and the seek of the magnetic head; Equipped with The controller a first write control means for writing first data and second data to each sector of a predetermined track among the tracks; a second write control means for writing the first data to each of the sectors of a predetermined track among the tracks; a selection control means for predicting a time required from the start of processing by the first write control means to the end of processing when a write command is received, and for selectively executing one of the processing by the first write control means and the processing by the second write control means by comparing the predicted time with a predetermined time limit; Including, Magnetic disk device.

2. When receiving the write command, the selection control means predicts the time required from the start of processing by the first write control means to the end of processing, and if the predicted time is equal to or shorter than a pre-specified time limit, executes the processing by the first write control means, and if the predicted time is longer than the pre-specified time limit, executes the processing by the second write control means.

2. The magnetic disk drive according to claim 1.

3. the magnetic disk includes a plurality of tracks for recording data, each of which is made up of a plurality of first sectors aligned in the circumferential direction and at least one second sector following the alignment of the first sectors, and these tracks are aligned in the radial direction; 2. The magnetic disk drive according to claim 1.

4. the first write control means writes the first data to the first sectors of a predetermined track among the tracks, and writes the second data to the second sectors of the predetermined track; the second write control means writes the first data to each of the first sectors of a predetermined track among the tracks; 4. The magnetic disk drive according to claim 3.

5. the first write control means causes the magnetic head to seek a predetermined track among the tracks, and writes the first data to a predetermined number of first sectors from the beginning of the first sectors of the predetermined track as the magnetic disk rotates, and after writing of the first data is completed, writes the second data to the second sector of the predetermined track as the magnetic disk rotates, the first write control means causes the magnetic head to seek a predetermined track among the tracks, and writes the first data into a predetermined number of first sectors from the beginning of the first sectors of the predetermined track as the magnetic disk rotates; 4. The magnetic disk drive according to claim 3.

6. the first write control means, after completing the writing of the second data, notifies the sender of the write command of the completion of the process; the second write control means, after completing the writing of the first data, notifies the sender of the write command of the completion of the process; 2. The magnetic disk drive according to claim 1.

7. The time limit is a latency limit specified by a CDL function of an external device.

2. The magnetic disk drive according to claim 1.

8. the first data is user data, The second data is an error correction code that performs error detection and correction on the user data for each track.

2. The magnetic disk drive according to claim 1.

9. the first data is user data, The second data is log data relating to the writing of the user data.

2. The magnetic disk drive according to claim 1.

10. a circular magnetic disk including a plurality of data recording tracks each consisting of a plurality of sectors aligned in a circumferential direction, the tracks being aligned in a radial direction; a magnetic head that is provided to be able to seek in the radial direction of the magnetic disk and that writes and reads data to and from the magnetic disk; a controller that controls the rotation of the magnetic disk and the seek of the magnetic head; A method for controlling a magnetic disk drive comprising: a first write control for writing first data and second data to each sector of a predetermined track among the tracks; a second write control for writing the first data to each sector of a predetermined track among the tracks; a selection control that, upon receiving a write command, predicts a time required from the start of processing of the first write control to the end of processing, and selectively executes either the processing of the first write control or the processing of the second write control by comparing the predicted time with a predetermined time limit; Including, A method for controlling a magnetic disk device.

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