JP2001014606A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make relievable adjacent tracks that have possibility of loosing data, by conducting a write retry to the tracks, reading the data recorded in arbitrary number of both side adjacent tracks that are specified from the tracks and overwriting the data on both side adjacent tracks. SOLUTION: A controller 106 outputs decoded data 203 from a coder decoder 104 to a host and outputs user data transmitted from the host into the coder decoder 104. Moreover, information, which positions a recording and reproducing head 102 to a target track by using servo detection information 204 from a servo detector 105, is computed and the information is outputted to a servo controller 107 as servo control signals 205. The user data are written into a R/W amplifier 103 and the coder decoder 104 and reading timing is outputted. The controller 107 conducts seek and position determination of the head 102 in accordance with the signals 205.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention seeks a magnetic recording / reproducing head for a specified track on a magnetic disk medium based on servo information recorded on the magnetic disk medium, and then performs positioning after seeking. The present invention relates to a magnetic disk device that performs data writing or data reading for a specified number of data sectors from a start data sector, and in particular, a magnetic disk device suitable for preventing data damage to adjacent tracks due to offset writing when a write fault occurs and its data protection. About the method.

2. Description of the Related Art In a conventional magnetic disk drive, there are a data surface servo method and a servo surface servo method as methods for controlling the positioning of a magnetic head. In particular, in the case of a small disk drive having a small number of disks rotating in synchronization with each other, the data surface servo method is often used because of its capacity advantage, but in this method the position information is intermittently recorded on the disk. Since there is a special arrangement, there is no means for knowing the position of the magnetic head between the position information and the next position information, and the position cannot be corrected. Therefore, even if the magnetic head is displaced due to a shock due to a disturbance during data writing, a write fault signal cannot be generated until the next position information data is read and the displacement of the magnetic head is detected.
In the meantime, there is a possibility that information on an adjacent track may be damaged by an offset write that is recorded along a locus close to the adjacent track. Therefore, a method of monitoring the envelope of a reproduced waveform with a magnetic head different from the magnetic head during recording, as described in JP-A-5-101520, has been proposed. This method reduces the envelope voltage if the magnetic head undergoes a large displacement due to the impact of a disturbance or the like, and if the magnetic head drops below a certain threshold voltage, it may record along the track adjacent to the adjacent track and damage the information on the adjacent track. Therefore, a write fault is generated and data write is prohibited.

In the conventional method, data is recorded on a locus close to an adjacent track due to variations in the detection accuracy of the envelope voltage and variations in the delay time of the detection circuit, thereby deteriorating the reliability of information on the adjacent track. Possibilities remain. Further, the same impact is applied when the track on the opposite side of the adjacent track is being written, and if data is recorded along a locus that is closer to the adjacent track that has been damaged earlier, the adjacent track will receive a signal from both tracks. And the reliability of data reproduction is significantly reduced. SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable magnetic disk device that, when a write fault occurs during data write, relieves an adjacent track that may receive data due to interference.

In order to achieve the above object, the present invention detects the position information of a recording / reproducing head, and detects that the recording / reproducing head is displaced from the track due to disturbance or the like. Means for calculating a data sector on an adjacent track that may have suffered interference from an adjacent track in the direction of the position shift and a place where the position shift has occurred, reading information of the data sector, and overwriting means; Is provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a magnetic disk drive will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to one embodiment of the present invention. 101 is a magnetic disk medium on which data is recorded, and 102 is a recording / reproducing head for writing and reading data to and from the magnetic disk medium 101.
Here, a plurality of magnetic disk media 101 are provided by lamination, and the recording / reproducing heads 102 are provided corresponding to the respective data surfaces of the respective magnetic disk media 101. A large number of concentric tracks are formed on both sides of the magnetic disk medium 101, and a plurality of servo areas on which servo information used for positioning control of the recording / reproducing head 102 is recorded are arranged at equal intervals on each track. Have been. These servo areas are radially arranged on the magnetic disk medium 101 over the respective tracks from the center. A data area is provided between the servo areas, and a plurality of data sectors storing user data are arranged. The read / write amplifier 103 is driven by the recording / reproducing head 102 to
A drive current for the recording / reproducing head 102 is generated in accordance with the amplification of the read signal 201 read from 1 and the encoded data 208 encoded by the codec 104. Code decoder 1
04 decodes the amplified signal 202 amplified by the read / write amplifier 103 and encodes the write data 207 sent from the controller 106. The servo detector 105 detects cylinder information, sector information, and burst information used for positioning the recording / reproducing head 102 from the amplified signal 202 amplified by the read / write amplifier 103, and outputs it to the controller 106. Controller 106 outputs decoded data 203 input from code decoder 104 to the host, and outputs user data sent from the host to code decoder 104. on the other hand,
The servo detection information (cylinder information, sector information, burst information) 204 sent from the servo detector 105 is used to calculate information necessary for positioning the recording / reproducing head 102 on a target track, and a servo control signal At the same time as outputting to the servo controller 107 as 205, the writing and reading timing of user data is output to the read / write amplifier 103 and the code decoder 104. The servo controller 107 follows the servo control signal 205 received from the controller 106,
The seek and positioning of the recording / reproducing head 102 are performed. By operating as described above, the magnetic disk device writes and reads data. Next, the operation of the magnetic disk device when a shock due to disturbance or the like is applied to the magnetic disk device during data writing and a write fault occurs will be described with reference to FIG. The format in the figure is a linear representation of a part of the format of one track. Data sectors 2, 3 in which user data is stored between servos 1 and 2 indicating servo areas.
4 are arranged. The previous data sector 1 is arranged before the servo 1, and the next data sectors 5 and 6 are arranged after the servo 2. The write gate opens only in the data sector, and closes in servos 1 and 2. Here, it is assumed that a shock due to disturbance or the like is given to the magnetic disk device as shown by the magnitude of the disturbance / shock in the figure. Data sector 1, servo 1,
Since no shock due to disturbance or the like is given to the magnetic disk device up to the data sector 2, the recording / reproducing head 102
_1 and 102_2, it is stably positioned on its own track. Thereafter, an impact due to a disturbance or the like is given from the middle of the data sector 3, and the recording / reproducing head 102 positioned on the own track is displaced toward an adjacent track on the outer peripheral side as indicated by 102_3 due to the influence. Here, the direction of impact due to disturbance or the like indicates a case where the recording / reproducing head 102 is displaced toward the outer peripheral side. Of course, if an impact in the reverse direction is applied, the recording / reproducing head 102 is displaced toward the inner peripheral side. The shock due to disturbance or the like continues to the middle of the data sector 4 and the servo 2, so that the read / write head
The displacement amount of 102 increases to 102_4 and 102_5.
In the servo 2, the servo information is detected by the servo detector 105, and it is detected that the recording / reproducing head 102 is displaced, and is output to the controller 106. The controller 106 generates a write fault signal using the servo detection information 204, closes the write gate, and stops the data write operation. In the figure, a write fault occurs in the middle of the data sector 5, and the write gate is closed. The controller 106 further generates a servo control signal 205 necessary for correcting the position shift from the position shift amount of the recording / reproducing head 102 and outputs the servo control signal 205 to the servo controller 107. In accordance with the servo control signal 205, the servo controller 107 corrects the positional deviation of the recording / reproducing head 102 and returns the same to the position 102_6. By performing this positional deviation correction for each servo area, a recording / reproducing head is
102 returns to its own track, and is in a state without positional displacement equivalent to 102_1 and 102_2. A format on the magnetic disk medium 101 when the recording / reproducing head 102 is displaced due to a shock such as a disturbance during data writing will be described with reference to FIG. FIG. 3A shows the format information actually written when the recording / reproducing head 102 is located on the track 1 and an impact as shown in FIG. 2 is applied. Since an impact is applied during the writing of the data sector 13 and the recording / reproducing head 102 is displaced toward the outer adjacent track 2, the data of the data sector 13 is written so as to approach the track 2. When the data sector 14 is further written, the displacement of the recording / reproducing head 102 becomes large, and the data sector 24
Part of it is rewritten. In the figure, the area indicated by hatching is overwritten. After that, the servo 12 detects the displacement of the recording / reproducing head 102 by the servo detector 105.
, A write fault is generated, the write operation is stopped, and the position error correction of the recording / reproducing head 102 is started. However, a write fault cannot be generated at the head of the data sector 15 due to a time delay of the position error detection. Therefore, a part of the data sector 25 is rewritten. When a write fault occurs, the controller 106 recognizes that data could not be written correctly, and writes data again by a certain number of sectors from the write fault detection timing. For example, since a write fault has not occurred in the servo 11, it is determined that data can be written up to the data sector 11 without any problem, and writing is performed again on the data sector 12 and subsequent sectors. As a result, as shown in FIG. 3B, the data sector of the track 1 is rewritten without any displacement of the recording / reproducing head 102, and a normal recording state is obtained. However, with respect to track 2, the recording / reproducing head 102
The effect of the offset write remains, and the data information remains lost in the hatched portions. Track 2 in this state
When data is read, the track width is reduced in the hatched portions in the data sectors 24 and 25, and the data read margin in the hatched portions is almost eliminated, or the error correction code (EC
There is a possibility that you need to be relieved in C). In this state, as shown in FIG. 3 (c), if an impact in the direction opposite to that of FIG. 3 (a) is applied while writing the track 3, the recording / reproducing head 102 is displaced toward the inner circumferential side adjacent track 2. , Data of the data sector 33 is written so as to approach the track 2. 3A, if the impact continues, the data sector 34 rewrites a part of the data sector 24 of the inner adjacent track 2. In the figure, data sector 2
This means that the area indicated by the hatching on the track 3 side of No. 4 has been overwritten. Similarly, the data sector 25 is overwritten in the area indicated by hatching on the track 3 side. Thereafter, the track 3 is rewritten by the same processing as in FIG. 3A, and the track 3 becomes as shown in FIG. 3D. Here, in the data sectors 24 and 25 of the track 2, the data information on both sides of the track 1 and the track 3 indicated by hatching is lost, and the track width is greatly reduced. There is a good possibility that the error correction code (ECC) needs to be remedied, or an unrecoverable unrecoverable error state has occurred. The unreadable unrecoverable error state is the worst state for a storage device and must be avoided. FIG. 5A is a flowchart of the above-described conventional processing method when a write fault occurs. First, when a write fault is detected in step 301, the write operation is stopped in step 302. Next, the recording / reproducing head 102 that has been displaced in Step 303 is sought on its own track to perform positioning. After that, the data is rewritten by going back by the specified number of data sectors from the data sector in which the write fault is detected, and the writing process is completed after completion. The present invention provides a method for avoiding the unreadable unrecoverable error state described above. The method according to the present invention will be described with reference to FIGS. 1, 2, 4 and 5 (b).
FIG. 4 is an explanatory diagram of a track sector state on a magnetic disk medium when a write fault occurs according to the present invention.
(b) is a rewrite processing flow when a write fault occurs according to the present invention. When a write fault is detected in step 301 of FIG. 5, the servo detector 105 of FIG. 1 detects in step 401 whether the displacement of the recording / reproducing head 102 is in the outer circumferential direction or in the inner circumferential direction, and outputs it to the controller 106 as servo detection information 204. I do. In step 302, the controller 106 closes the write gate in FIG. 2 and stops the write operation of the magnetic disk device. As a result, as shown in FIG. 4A, the data sectors 13 and 14 have been offset-written due to the displacement of the recording / reproducing head 102. Data sector 15
The offset write is also performed, but a write fault is detected on the way, and the write gate is closed so that the write is stopped at that point. Next, in step 303 of FIG. 5, the positional deviation of the recording / reproducing head 102 is corrected, and seek and positioning to the track 1 are performed. Further, in step 304, rewriting is performed retroactively by the number of data sectors specified on track 1. The number of sectors specified is, for example, servo 11
Since no write fault has been detected, it is determined that the data sector 11 has been written normally, and that the data sector 12 and thereafter are designated for rewriting. As a result, the track 1 is rewritten normally as shown in FIG. Thereafter, in the present invention, in steps 402, 403, and 404, a track whose data information may have been partially damaged by the offset write is restored. In step 402, the controller 106 determines which adjacent track on the outer peripheral side or the inner peripheral side may be damaged using the phase shift direction of the recording / reproducing head 102 detected in step 401.
Then, a servo control signal 205 is output to the servo controller 107,
The servo controller 107 selects the selected track, that is, FIG.
Then, the recording / reproducing head 102 is sought and positioned on the track 2. Next, in step 403, information of a data sector adjacent to the data sector rewritten in step 304 is read. FIG. 4 is based on an example in the description of step 304.
The information of the data sectors 22, 23, 24 and 25 of (b) is read. At this point, the format damage of the data sectors 24 and 25 is partly, and the track width is also partly reduced, so that the data can be read within the read margin or at least the possibility of reading the data by using an error correction code. Is high enough. Finally, by rewriting the data sector information read in step 404 to the same data sector again, the track 2 can be restored to a state without data damage as shown in FIG. Here, the data sectors 22, 23, 24, and 25 are caused by the impact of disturbance or the like.
If it is determined that a defect such as a scratch has occurred on the magnetic disk medium in the data sector such as, the data may be transferred to a replacement sector instead of rewriting to the same sector in step 404. This may be similarly written to the alternate sector for track 1. In this description, the data damage recovery processing for one adjacent track has been described. However, when it is determined that the data damage extends to a plurality of tracks, it can be dealt with by repeating steps 402 to 404 while shifting the target track. Further, in this description, in order to minimize the performance degradation of the magnetic disk device due to the rewriting operation, the embodiment has been described in which the misalignment direction is detected in step 401 and the data is restored only in the track in that direction. When emphasis is placed, when a write fault occurs, data damage repair processing similar to that described in this description may be performed on adjacent tracks on both sides.

According to the present invention, even if a write fault occurs due to a shock due to a disturbance or the like during data writing in a magnetic disk device and adjacent track information is damaged, rewriting of the damaged track can be performed. To do so, the data damage is restored. For this reason, it is possible to avoid a situation in which damage is repeatedly caused by a plurality of write faults (offset write), data quality is remarkably reduced, and a read-out state is not caused.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic disk device.

FIG. 2 is an explanatory diagram of the operation of the apparatus when a write fault occurs due to a disturbance.

FIG. 3 is an explanatory diagram of a conventional track sector state on a magnetic disk medium when a write fault occurs.

FIG. 4 is an explanatory diagram of a track sector state on a magnetic disk medium when a write fault occurs according to the present invention.

FIG. 5 is a flowchart of a rewriting process when a write fault occurs according to the related art and the present invention.

[Explanation of symbols]

101: magnetic disk medium, 102: recording / reproducing head, 103 ...
Read / write amplifier (R / W amplifier), 104 code decoder, 10
5 servo detector, 106 controller, 107 servo controller, 201 read signal, 202 amplified signal, 203 decoded data, 204 servo detection information, 205 servo control signal,
207: write data, 208: encoded data.

Claims (3)

[Claims] 1. A magnetic recording / reproducing head seeks to a specified track on a magnetic disk medium based on servo information recorded on the magnetic disk medium to perform positioning, and then specifies a specified track on the track. In a magnetic disk drive that performs data writing or data reading for the number of data sectors specified from the start data sector, if a write fault occurs during data writing to the track, a write retry to the track and a designation from the track are performed. A magnetic disk device for reading data recorded on an arbitrary number of adjacent tracks on both sides and overwriting the data on the adjacent tracks on both sides. 2. A magnetic recording / reproducing head seeks to a specified track on a magnetic disk medium based on servo information recorded on the magnetic disk medium to perform positioning, and then specifies a specified track on the track. In a magnetic disk device that performs data writing or data reading for a specified number of data sectors from a start data sector, when a write fault occurs during data writing to the track, the direction of the position change of the magnetic recording / reproducing head is changed. Detecting, performing a write retry on the track and reading data recorded on a specified number of one-side adjacent tracks on the direction side of the position change, and overwriting the data on the one-side adjacent track. Characteristic magnetic disk drive. 3. A magnetic recording / reproducing head seeks to a specified track on the magnetic disk medium based on servo information recorded on the magnetic disk medium to perform positioning, and then specifies a specified track on the track. In a magnetic disk drive that performs data writing or data reading for the number of data sectors specified from the start data sector, if a write fault occurs during data writing to the track, a write retry to the track and a designation from the track are performed. The data recorded on the arbitrary number of adjacent tracks on both sides is read, and when it is determined that the adjacent tracks on both sides are damaged such as the defect of the magnetic disk medium, the data is written to the replacement track for replacement. A magnetic disk drive characterized by the above-mentioned.