KR19980026631A - Auto Defect Servo Sector Replacement for Hard Disk Drives - Google Patents

Abstract

end. TECHNICAL FIELD The present invention relates to a method for automatically replacing a defect servosector of a hard disk drive used as an auxiliary memory device of a computer system.

I. The present invention has been made in an effort to provide a method for automatically replacing a defect servosector, which can automatically replace a defect servosector with a new one.

All. Summary of the Invention Solution of the Invention: A Defect Servo Sector Automatic Replacement Method for a Hard Disk Drive Using a Prebit-Racked Disc as a Recording Medium. The data read / write is performed by replacing a sector with a predetermined servo sector existing on the bit stack.

la. Significant Use of the Invention: Can be used in the method of replacing the defect servosector of a hard disk drive employing the embedded servosector method.

Description

Auto Defect Servo Sector Replacement for Hard Disk Drives

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard disk drive used as an auxiliary storage device of a computer system, and more particularly, to a method for automatically replacing a defective servo sector and a servo track with a new servo sector and a servo track.

In a hard disk drive, which is widely used as a secondary storage device of a computer system, data is stored in tracks arranged concentrically on the surface of the disk and arranged to extend circumferentially, and the tracks are recorded again. Data sector and servo sector in which servo information is recorded. In order to write or read data to a data sector at an arbitrary position on the disc, the head must be moved to the track where the data sector exists and placed on the track. In this way, moving the head to any desired track is called track search, and keeping the head accurately on the searched track is called track tracking. At this time, in order to move and position the head to a specific track, it is necessary to know the position of the head relative to the tracks. The information indicating the position of the head relative to the tracks is called servo information. The servo information has a unique pattern. This servo information is written permanently on the disk in advance by the servo writer when assembling the hard disk drive. Hereinafter, a zone layout on a general disk will be described with reference to FIG. 1.

FIG. 1 shows a zone layout of a disc employing an embedded servo sector method, in which a plurality of servo sectors 4 having the same length and a data zone in which user data is recorded. Zone: referred to as DZ). The data zone is again composed of a plurality of tracks, and in the following description, it is assumed that there are eight data zones on the disc 2. On the other hand, the parking zone (Parking Zone: PZ) in which the head is parked when the power is turned off is located in the innermost peripheral area on the disk 2, and there is an inner guard band (IGB) just outside the parking zone. In addition, the outermost peripheral area on the disc 2 is provided with a system zone (called SZ), which is commonly referred to as a maintenance zone, to record replacement information for the defective servo sector and information for various system maintenance. Hereinafter, a general countermeasure when the servo information is damaged due to a defect of a servo sector in a hard disk drive using the disk having the above-described zone layout as a recording medium will be described.

First of all, if the drive fails to operate normally due to corruption of servo information, the measures are different for each manufacturer of hard disk drives, but the following methods are generally adopted. First, if a signal quality problem of the servo information occurs immediately after the servo light process, some manufacturers wish to make the signal state of the servo information acceptable by vaguely reserving the servo information. Some products are designed so that bad servo sectors are not affected by future operation by constructing the product design so as not to use the bad servo sector by bad marking up to the bad servo sector. . Secondly, the problem of servo information corruption can occur not only in the test process after the basic product completion stage but also when the user uses the drive. If the servo information is damaged when using the drive, the user must return or discard the product due to the inability to perform normal read / write operations. That is, in the conventional hard disk drive, if the normal servo control is impossible due to the damage or deterioration of the servo information generated during the use of the drive, there is a problem that the life of the drive must be terminated because there is no countermeasure.

Accordingly, an object of the present invention is to provide a method for automatically replacing a defect servosector which can automatically replace a defect servosector generated when a hard disk drive is used with a new servosector.

Another object of the present invention is to provide a method for automatically replacing a defect servo sector which can automatically replace a track with a new track when a large number of defect servo sectors occur on the same track when a hard disk drive is used.

1 is a zone layout diagram of a disk 10 employing an embedded servo sector method.

2 is a block diagram of a general hard disk drive.

3 is a sector format diagram of one predetermined track among tracks constituting each zone on the disc 10 having the zone layout of FIG.

In order to achieve the above object, the present invention provides a method for automatically replacing a defect servo sector in a hard disk drive using a disc equipped with an bit stack, where a data read / write operation is impossible due to the generation of a defect servo sector. The data is read / written by replacing the servo sector with a predetermined servo sector existing on the prebit rack.

Hereinafter, an operation according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, many specific details such as the number of data zones, the number of tracks in each data zone, and the size of data sectors (bytes) are shown to provide a more general understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 is a block diagram of a general hard disk drive. It is assumed that a hard disk drive according to an embodiment of the present invention includes three disks 10 and six heads 8 corresponding thereto. . Referring to FIG. 2, the microprocessor 2 includes a programmable read only memory (PROM) 4 storing a predetermined control program of the microprocessor 2, and a static random access. Memory (hereinafter referred to as SRAM) (6). The head 8 is attached to one end of the actuator to perform horizontal movement on the disk 10 as a recording medium and to read and write data on the disk 10. The voice coil motor (VCM) 12 located at the other end of the actuator with the head 8 attached to one end is horizontally driven on the disk 10 in correspondence with the applied current level and direction. The spindle motor 14 rotates the disk 10 mounted on the drive shaft in accordance with a control signal input from the motor driver 20. The VCM driver 16 is connected to the VCM 12 to control the driving of the VCM 12. A digital-to-analog converter (DAC) 18 is connected to the microprocessor 2 and the VCM driver 16 and receives a digital control input signal U from the microprocessor 2 and converts it into an analog signal. Output to the VCM driver 16.

The motor driver 20 is connected to the spindle motor 14 and the microprocessor 2 and controls the driving of the spindle motor 14 under the control of the microprocessor 2. A pre-amplifier 22 is connected to the head 8 to amplify and output the read signal and to output the input signal to be written to the head 8. The read / write channel circuit 24 is connected to the microprocessor 2, the preamplifier 22 and the interface controller 30, and receives writing data from the interface controller 30 under the control of the microprocessor 2. This is encoded and output to the preamplifier 22. In addition, the read / write channel circuit 24 digitally converts the analog reading signal input from the preamplifier 22 and outputs the encoded read data (ERD). An analog-to-digital converter (ADC) 26 is connected to the read / write channel circuit 24 to receive an analog servo reading signal, and digitally converts it to PES and outputs it to the microprocessor 2. A gate array 28 is connected to the read / write channel circuit 24 to receive an ERD signal, and detects and outputs servo information such as gray codes in the servo region of the disk 10 from the ERD signal. do. The interface controller 30 transmits and receives data between the external data input device (for example, a host computer) and the disk 10. In a general hard disk drive having the above-described configuration, the actual configuration of the present invention is a Defect servosector and servo track automatic replacement part to be implemented and embedded in drive firmware, and does not require additional hardware or a separate device. However, if a register for storing the servo error code as a result of comprehensive determination of the servo-related error is prepared for storing and analyzing the details of the servo error, the present invention is easier to implement, but without additional storage means The servo error code may be stored by using one of the memories (or registers) allocated to the control system or one of the memories allocated to the gate array 28 or the interface controller 30. Hereinafter, a case where a defect servo sector occurs on a predetermined track among tracks arranged concentrically on the disk 10 and when a large number of defect servo sectors occur on the same track (hereinafter referred to as a defect servo track). ), The replacement of the new servo sector and the method of replacing the servo track will be described in detail.

First, FIG. 3 constitutes an outer zone (Outter Zone: OZ), a middle zone (MZ), and an inner zone (Inner Zone: IZ) on the disc 10 having the zone layout of FIG. Figure 1 shows a format diagram for one of the tracks. The basic characteristics of the disc employing the embedded servo sector method are the same as the number of servo sectors per track regardless of each data zone as shown in FIG. 1, but the number of data sectors is the outer zone as shown in FIG. 3. OZ) increases. That is, if there is one data sector per servo sector in a track in the median zone MZ, 1.5 and 0.7 data sectors per servo sector exist in the outer zone OZ and the inner zone IZ, respectively. Hereinafter, an embodiment of the present invention will be described with respect to a method for replacing a defect servo track with a new prebeat track.

First, a requirement to be preceded in order to replace a new track when the above-mentioned Defect servo track occurs is to prepare a spare track on the disc 10 in advance. The easiest and least troublesome way to do this is to set up all or one or two tracks of the outermost cylinders of each zone (IZ, MZ, OZ) as spares. In one embodiment of the present invention, Only one outermost track is set. Hereinafter, a method for replacing a defect servo track when the servo control is impossible due to the generation of a plurality of defect servo sectors will be described as follows.

First, if a plurality of defect servo sectors are generated on the same track and normal data write operation is impossible, the microprocessor 2 moves the head 8 to a prebeat rack provided in the zone including the defect servo track. Write data received from the host computer on the track. The microprocessor 2 then stores the information about the bit stack in the system cylinder and the SRAM 6 provided in the system zone SZ on the disk 10, respectively. Then, if you want to access the Defect servo track, the microprocessor 2 needs to access the replaced Yebit track. If the power is off and then on, the microprocessor 2 reads the information about the prebeat track stored on the system cylinder when the Defect servo track is replaced after the drive ready state. ), And a flag to indicate that there is alternative information is set on. As a result, each data access checks the presence or absence of the replacement information flag for the Defect servo track, and if the replacement information or not flag is set, the track search is performed with the bit track with reference to the replacement information loaded at power-on. In this case, the overhead of the microprocessor 2 may be increased, but since it is stochastic, it does not significantly affect the overall performance. Hereinafter, a method of replacing a defect servo track when the normal data read operation is impossible due to the occurrence of a defect servo track will be described.

If the position error signal maintains the high level due to the defect servo track during the data read command, the microprocessor 2 repeatedly performs the subroutine for the data read retry. If the data read is not performed even with all the methods for data read retry (e.g., retry subroutine or ECC), the microprocessor 2 reads the data read embedded in the interface controller 30 IC. The information recorded in the error-related registers (ie, task registers and status registers) is analyzed to determine whether to apply the Defect servo track replacement algorithm according to an embodiment of the present invention. If it is determined that the Defect servo track should be replaced with a new prebeat track, the microprocessor (2) sets the currently waiting track in the highest rank among the prebeat tracks and then reads all data that can be read on the defect servo track. . Thereafter, the microprocessor 2 writes all the read data on the one-to-one mapped data sector on the pre-set bit rack, and processes the unrestored data as lost data. Thereafter, the microprocessor 2 may perform a data read operation by checking a substitute information presence flag every time an access to the corresponding defect servo track is performed, as in the data write operation described above.

Meanwhile, although an embodiment of the present invention has described an alternative method for the defect servo track, it may be replaced with a new servo sector when the defect servo sector is generated without any modification.

As described above, the present invention contributes to securing the lifetime and reliability of the drive by one-to-one mapping of pre-set bit tracks or spare sectors when the normal data read / write operation cannot be performed due to the generation of the defect servo sector when the hard disk drive is used. There is an advantage to this.

Claims (5)

In the method for automatically replacing the defect servo sector of a hard disk drive using a disk equipped with a bite track as a recording medium, If the data read / write operation is impossible due to the generation of the defect servo sector, the defect servo sector is automatically replaced by a predetermined servo sector existing on the pre-beat track. The method of claim 1, wherein when the defect servosector exceeds a predetermined value on the same track, the tracks are replaced with the prebeat tracks to read / write data. The method of claim 1 or 2, further comprising: when the defect servo sector is replaced with the spare sector, replacing the defect servo sector with information about the defect servo sector on a system cylinder, and using the same every time the data is accessed. Defect servo sector automatic replacement method. 4. The method of claim 3, wherein the servo information recorded on the disc is servo information recorded in an embedded servo sector method. In a hard disk drive employing a zone bit recording method in which each bit has a prebeat rack, If the data read / write operation is not possible due to the generation of the defect servo sector, the defect servo sector is replaced with a predetermined servo sector on the prebeat track in the corresponding zone, and the replacement information for the defect servo sector is recorded on the system cylinder on the disk. And a data read / write function by accessing a servo sector corresponding to the substitute information loaded every time the data is accessed.