KR100640666B1 - Method for managing track defect in data storage system and disc drive using the same - Google Patents

Abstract

A method for managing a track defect in a data storage system and a disc drive using the same are provided to improve the reliability of data by evaluating the probability of off track erase in tracks adjacent to a corresponding track having an unstable position error signal to determine the defect of the corresponding track. A corresponding track, on which a position error signal is abnormally detected, is searched on a disc(S303). When the position error signal is abnormally detected as the search result, it is determined whether data are erased in tracks adjacent to the corresponding track by the influence of off track erase according to a write operation of the corresponding track(S313). When the data are erased in the tracks adjacent to the corresponding track, the corresponding track is defect-processed(S314).

Description

Method for managing track defect in data storage system and disc drive using the same}

1 is a plan view of a head disk assembly of a disk drive to which the present invention is applied.

2 is an electrical circuit diagram of a disk drive to which the track defect management method in the data storage system according to the present invention is applied.

3 is a flowchart of a track defect management method in a data storage system according to the present invention.

The present invention relates to a method and apparatus for managing defects of a data storage system, and more particularly, to a method and apparatus for managing track defects that may be generated due to instability of a position error signal (PES) in a disk drive. will be.

In general, a hard disk drive, which is one of data storage devices, contributes to computer system operation by reproducing data recorded on a disk by a magnetic head or recording user data on the disk. As such hard disk drives are gradually increasing in capacity, density, and miniaturization, bit per inch (BPI), the recording density in the direction of disk rotation, and track per inch (TPI), the recording density in the radial direction, are increasing. Is required.

As the recording density of discs increases, if the mechanism of the hard disk drive is not refined, Off-Track Erase (OTE) occurs that intrudes adjacent tracks and erases the data of adjacent tracks during write mode. Increase the likelihood.

In the process of recording servo information according to the servo write process, which is one of the processes for manufacturing a hard disk drive, servo information may not be correctly recorded according to design specifications due to disturbance or the like. have. In this case, when the corresponding track is written, the position error signal PES becomes unstable, and the magnetic head may invade the adjacent track, thereby losing information stored in the adjacent track. In order to solve the problems occurring in some specific tracks, giving a TPI margin causes another problem of low recording density of the disc.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a data storage system for evaluating the possibility of off-track erasing on adjacent tracks of tracks having unstable position error signals in a hard disk drive to determine the defects of the tracks. To provide a track defect management method and a disk drive using the same.

In order to achieve the above technical problem, the track defect management method in a data storage system according to the present invention is a defect management method in a data storage system, the method comprising: (a) searching for a track on which a position error signal is abnormally detected on a disc; ; (b) In the case where the track N whose position error signal is abnormally detected as a result of the search in step (b) is searched, the off track due to the write operation of the track N where the position error signal is abnormally detected. Determining whether data is erased from the adjacent track (N-1 or N + 1) by the influence of the ease; And (c) defecting the track N in which the position error signal is abnormally detected when data is deleted from the track N-1 or N + 1 as a result of the determination of step (b). It is characterized by.

According to another aspect of the present invention, there is provided a disk drive, comprising: a disk for storing data; Searching for tracks in which position error signals are abnormally detected on the disc, and when track N for abnormally detecting position error signals is searched, due to the off-track erasure effect according to the write operation of the tracks N A controller configured to determine whether data is erased from an adjacent track (N-1 or N + 1) and to decompensate the track (N) when the data is erased from the track (N-1 or N + 1); And a write / read circuit for performing data processing for writing data to or reading data from the disk.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hard disk drives consist of a combination of electrical circuits and a head disk assembly (HDA) consisting of mechanical components.

1 shows a configuration of a head disk assembly (HDA) 10 of a hard disk drive to which the present invention is applied.

The head disk assembly 10 includes at least one magnetic disk 12 that is rotated by the spindle motor 14. The disk drive 10 also includes a transducer 16 located adjacent to the surface of the disk 12.

The transducer 16 can read or write information on the rotating disk 12 by sensing and magnetizing the magnetic field of each disk 12. Typically transducer 16 is coupled to the surface of each disk 12. Although illustrated and described as a single transducer 16, it should be understood that this consists of a write transducer for magnetizing the disc 12 and a separate read transducer for sensing the magnetic field of the disc 12. Read transducers are constructed from Magneto-Resistive (MR) devices. The transducer 16 is also commonly referred to as a head.

The transducer 16 can be integrated into the slider 20. The slider 20 is structured to create an air bearing between the transducer 16 and the surface of the disk 12. The slider 20 is coupled to the head gimbal assembly 22. The head gimbal assembly 22 is attached to an actuator arm 24 having a voice coil 26. The voice coil 26 is located adjacent to the magnetic assembly 28 that specifies the voice coil motor 30 (VCM). The current supplied to the voice coil 26 generates a torque for rotating the actuator arm 24 relative to the bearing assembly 32. Rotation of the actuator arm 24 will move the transducer 16 across the disk 12 surface.

The information is typically stored in an annular track of the disc 12. Each track 34 generally includes a plurality of sectors. Each sector includes a data field and an identification field. The identification field is composed of a gray code identifying a sector and a track (cylinder). The transducer 16 is moved across the surface of the disc 12 to read or write information on other tracks.

The disk 12 is largely divided into a maintenance cylinder (generally referred to as MC) area and a user data area for storing information related to the disk drive. The maintenance cylinder area stores various information related to the disc drive, including defect list information and read / write optimization parameter information, and is an area that a user cannot access arbitrarily. The user data area is an area in which a user can substantially write or read data. The user data area of the disk 12 is divided into a plurality of zones, each of which is assigned a spare cylinder for replacing a defect sector.

2 shows an electrical system 40 capable of controlling a hard disk drive. The electrical system 40 includes a controller 42 coupled to the converter 16 by a lead / right (R / W) channel circuit 44 and a pre-amp circuit 46.

The controller 42 may be a digital signal processor (DSP), a microprocessor, a microcontroller, or the like. The controller 42 reads information from the disk 12 or writes information to the disk 12 according to a command received from a host device (not shown in the drawing) via the host interface circuit 54. The read / write channel circuit 44 is controlled.

The controller 42 is also coupled to a VCM drive circuit 48 that supplies a drive current to the voice coil 26. The controller 42 supplies a control signal to the VCM driver 48 to control the excitation of the voice coil motor and the movement of the transducer 16.

The ROM 50 stores firmware and various control data for controlling the disk drive. Of course, programs for executing the flowchart of the track defect management method in the data storage system according to the present invention shown in Fig. 3 are also stored.

When power is supplied to the disk drive, the RAM 52 loads various parameter information and defect list information, which are disk drive information read from a maintenance cylinder position of the disk 12.

First, the operation of a general disk drive will be described.

In the data read mode, the disc drive amplifies the electrical signal sensed by the transducer 16 from the disc 12 in the preamplifier 45 to facilitate signal processing. The read / write channel circuit 44 then encodes the signal read out from the disk 12 into digital signals in accordance with sector pulses generated by the controller 42, converts the signal into stream data, and converts the host interface circuit 54 into a stream signal. To the host device.

Next, in the write mode, the disk drive receives data from the host device (not shown) through the host interface circuit 54 and temporarily transmits the data to an internal buffer (not shown) of the host interface circuit 54. After storing, the data stored in the buffer is sequentially output and converted into a binary data stream suitable for the recording channel of the disc 12 by the read / write channel circuit 44, and then at the time when the sector pulse is generated, the preamplifier 45 Is recorded on the disc 12 through the converter 16 with the recording current amplified by the "

According to the present invention, the controller 42 searches for a track in which a position error signal is abnormally detected on a disk in a function test process, which is one of manufacturing processes of a hard disk drive, and abnormally detects a position error signal. When the track N is searched, it is determined whether data is erased from the adjacent track N-1 or N + 1 due to the off track erasure effect according to the write operation of the track N. If data is deleted at -1 or N + 1), the track N is defected and the track N is updated to be updated in the defect list.

Next, a track defect management method in the data storage system according to the present invention executed under the control of the controller 42 will be described in detail with reference to the flowchart of FIG. 3.

The manufacturing process of the disc drive includes the servo write process, which writes servo information to the disc, the function test process to test the general function of the disc drive, and the burn-in to test the reliability of the disc drive at high temperatures. Divided into test processes and the like.

The track defect management process according to the present invention is executed as an example in a functional test process. Of course, it can also be designed to run in other processes.

Random seek is performed before seeking the target track N to be tested (S301). This is to increase the accuracy of the test.

After executing the random seek, the target track N to be tested is seek (S302). Set N = 0 as the initial setting value.

After the track N is seeked, the position error signal PES is measured (S303).

Then, it is determined whether the position error signal measured in the track N is normal (S304). The normality of the position error signal is determined by comparing the magnitude of the measured position error signal with the initially set threshold value, and is determined to be abnormal when the magnitude of the measured position error signal is smaller than the threshold value. Here, the threshold value is determined based on the experimental value at the time of design in consideration of characteristics such as the recording density of the hard disk drive. In the present invention, the threshold value for determining whether the position error signal is normal is set to a boundary value that guarantees servo control with a constant margin at the time of position control of the transducer 16, and the position error signal below the threshold value is The detection does not necessarily mean that the track is bad.

When it is determined in step 304 (S304) that the position error signal measured in track N is normal, it is determined whether track N corresponds to track N_max, which is the last track of the disc (S315). That is, it is determined whether the N value is greater than or equal to N_max.

If the value N is greater than or equal to N_max as a result of the determination in step 315 (S315), the process ends as the case where the position error signal has been examined up to the last track of the disc.

When the value of N is smaller than N_max as a result of the determination in step 315 (S315), the track number N is increased by 1 and the process returns to step 301 (S301) and the above steps are repeated.

However, if it is determined that the position error signal is abnormal because the magnitude of the position error signal measured in the track N is smaller than the threshold as a result of the determination in step 304 (S304), the tracks N-1 and N which are tracks adjacent to the track N The first test data is written to +1, respectively (S305).

In steps 305 (S305) to 314 (S314), data is erased from adjacent tracks N-1 or N + 1 due to the effect of off-track erasure due to the write operation of track N in which the position error signal is abnormally detected. Is a process of determining whether or not a defect is likely to occur and track defect processing.

After executing step 305 (S305), the counter (not shown) nTry in the controller 42 is reset to 0 (S306).

Next, random seek for seeking an arbitrary track is executed (S307). This is also to increase the accuracy of the test.

After the random seek of step 307 (S307) is executed, track N is again sought, and then second test data is written to track N (S308).

After executing step 308 (S308), the value of the counter nTry is compared with the nTry_max value, which is an initial setting value (S309). Here, the value of nTry_max is a value for determining the number of times to be repeatedly written to track N. In the present invention, nTry_max value is determined as 99 as an example. For reference, if nTry_max = 99 is determined, the write is repeated 100 times on track N.

If the counter nTry value is smaller than the nTry_max value as a result of the comparison in step 309 (S309), after increasing the value of the counter nTry by one (S310), the process returns to step 307 (S307) to execute random seek and re-enter the track N again. 2 Write the test data.

If the result of the comparison in step 309 (S309) indicates that the value of the counter nTry is greater than or equal to the value of nTry_max, the tracks N in tracks N-2 and N + 2 are tracks adjacent to tracks N-1 and N + 1, respectively. The third test data is written off track by a specific amount (A%) (S311). Here, it is effective to determine the off track amount in consideration of the recording density of the disc and the like, which can be set to 13% as an example. In this case, the third test data is written after + 13% off track N-2 and -13% off track N + 2.

After executing step 311 (S311), tracks N-1 and N + 1 are read (S312), respectively, and tracks N-1 and N + 1 determine whether the first test data is normally read. (S313).

If the data read fails in any of the tracks N-1 or N + 1 as a result of the determination in step 313 (S313), the process returns to step 315 (S315) after defecting the track N (S314). This is the case when data is erased from adjacent tracks N-1 or N + 1 due to the influence of Off-Track Erase (OTE) caused by the write operation of track N where position error signal is abnormally detected. .

However, in the case where both tracks N-1 and N + 1 succeed in data read as a result of the determination in step 313 (S313), even if a position error signal is abnormally detected, the resulting off track erasure failure does not occur in adjacent tracks. Therefore, the track N returns to step 315 (S315) without defecting.

As described in the above process, in a track in which the position error signal is detected to be relatively smaller than a normal case, it is determined whether the track is defected by considering the effect on the adjacent track (that is, the possibility of off-track erasing).

The invention can be practiced as a method, apparatus, system, or the like. When implemented in software, the constituent means of the present invention are code segments that necessarily perform the necessary work. The program or code segments may be stored in a processor readable medium or transmitted by a computer data signal coupled with a carrier on a transmission medium or network. Processor readable media includes any medium that can store or transmit information. Examples of processor-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memory, erasable ROM (EROM), floppy disks, optical disks, hard disks, optical fiber media, radio frequency (RF) networks, Etc. Computer data signals include any signal that can propagate over transmission media such as electronic network channels, optical fibers, air, electromagnetic fields, RF networks, and the like.

Specific embodiments shown and described in the accompanying drawings are only to be understood as an example of the present invention, not to limit the scope of the invention, but also within the scope of the technical spirit described in the present invention in the technical field to which the present invention belongs As various other changes may occur, it is obvious that the invention is not limited to the specific constructions and arrangements shown or described. That is, it is a matter of course that the present invention can be applied not only to various disk drives including hard disk drives, but also to various kinds of data storage devices.

As described above, according to the present invention, the track detected by the position error signal smaller than the normal case is determined whether or not off track erasure occurs in the adjacent track to determine whether or not the track defect, thereby improving the reliability of the data recorded in the disc drive. In addition, the effect of increasing the recording density of the disc is generated.

Claims (8)

In the defect management method in the data storage system, (a) searching for a track on which the position error signal is abnormally detected on the disk; (b) In the case where the track N whose position error signal is abnormally detected as a result of the search in step (b) is searched, the off track due to the write operation of the track N where the position error signal is abnormally detected. Determining whether data is erased from the adjacent track (N-1 or N + 1) by the influence of the ease; And (c) when the data of the track N-1 or N + 1 is erased as a result of the determination of step (b), decompiling the track N in which the position error signal is abnormally detected. The track defect management method in the data storage system characterized by the above-mentioned. 2. The track of claim 1, wherein the step (a) determines that the track where the magnitude of the position error signal is detected is smaller than a predetermined threshold value as the track where the position error signal is abnormally detected. Defect management method. The method of claim 1, wherein step (b) (b1) writing first test data on each of adjacent tracks (N-1 and N + 1) of the track (N) where the position error signal is abnormally detected; (b2) repeatedly writing the second test data a predetermined number of times to the track N at which the position error signal is abnormally detected; (b3) writing third test data by off-tracking a predetermined amount toward track N on tracks N-2 and N + 2 adjacent to tracks N-1 and N + 1, respectively; And (b4) In the case where the track N-1 or N + 1 is read and the first test data is not read normally, the off track due to the write operation of the track N in which the position error signal is abnormally detected. And determining that data has been erased from adjacent tracks (N-1 or N + 1) by the influence of the cause. 4. The data storage system as claimed in claim 3, further comprising the step of randomly seeking a predetermined track prior to the write execution each time the write is repeatedly performed on the track N in the step (b2). How to manage track defects. In the data storage device, A disk for storing data; Searching for tracks in which position error signals are abnormally detected on the disc, and when track N for abnormally detecting position error signals is searched, due to the off-track erasure effect according to the write operation of the tracks N A controller configured to determine whether data is erased from an adjacent track (N-1 or N + 1) and to decompensate the track (N) when the data is erased from the track (N-1 or N + 1); And And a write / read circuit for performing data processing for writing data to or reading data from the disk. The disk drive of claim 5, wherein the controller determines that the track is a track in which the position error signal is abnormally detected when the magnitude of the position error signal detected on the disk is smaller than a predetermined threshold. . 6. The controller according to claim 5, wherein the controller writes first test data to each of adjacent tracks (N-1 and N + 1) of the track (N) where the position error signal is abnormally detected, and the track (N). The second test data is repeatedly written to a predetermined number of times, and the tracks N-2 and N + 2 adjacent to the tracks N-1 and N + 1, respectively, by a predetermined amount toward the track N, respectively. The track N where the position error signal is abnormally detected when the third test data is off-tracked to write the track N-1 or N + 1 and the first test data is not read normally. And determining that data has been erased from adjacent tracks (N-1 or N + 1) due to the off-track erasure effect according to the write operation of the disk drive. 8. The disk drive according to claim 7, wherein the controller controls to randomly seek a predetermined track prior to the write execution whenever the write (N) is repeatedly executed.

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