KR100420992B1 - Method for automatically replacing defect servo sector of hard disk drive - Google Patents

Abstract

PURPOSE: A method for automatically replacing a defect servo sector of an HDD(Hard Disk Drive) is provided to replace a defect servo sector with a predetermined servo sector existing on a preliminary track if a data read/write operation is impossible owing to the defect servo sector, thereby extending a life of the HDD. CONSTITUTION: When a data read/write operation is impossible owing to a defect servo sector, a system replaces the corresponding defect servo sector with a predetermined servo sector existing on a preliminary track, and records data. While accessing the data, the system reads/writes the data by accessing the servo sector. If the defect servo sector is generated at more than a setup value on the same track, the system replaces the corresponding track with the preliminary track to read/write the data.

Description

How to Automatically Replace the Defective Servo Sectors of 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 of automatically replacing a servo sector and a servo track in which a defect occurs, into a new servo sector and a servo track.

In a hard disk drive widely used as an auxiliary storage device of a computer system, data is stored in tracks arranged concentrically on the surface of the disk and arranged in a circumferential direction, And a servo sector in which servo information is recorded. In order to write or read data to or from a data sector existing at an arbitrary position on the disk, the head must be moved to a track in which the data sector exists and positioned on the track. Moving the head to an arbitrary desired track is referred to as track seeking, and keeping the head accurately on the track is referred to as track following. 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 related to the tracks. The information indicating the position of the head related to the tracks is called servo information, and the servo information has a unique pattern. Such servo information is permanently written on the disk in advance by the servo writer when assembling the hard disk drive. Hereinafter, a general zone layout on a disk will be described with reference to FIG.

FIG. 1 shows a zone layout of a disk employing an embedded servo sector. The disk 2 includes a plurality of servo sectors 4 having the same length and a data zone Data Zone: 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, a parking zone (PZ) in which the head is parked when the power is turned off is located in the innermost peripheral region on the disk 2, and an IGB (Inner Guard Band) exists just outside the parking zone. In addition, a system zone (SZ), which is generally referred to as a maintenance zone, is provided in the outermost circumferential area on the disk 2, and replacement information for the defective servo sector and information for maintenance of various systems are recorded. Hereinafter, a description will be made of a general circumstance in the case where the servo information is damaged due to a defect of the servo sector in a hard disk drive using the disk having the zone layout described above as a recording medium.

First of all, if the drive can not be driven normally due to the damage of the servo information, measures are different for each hard disk drive manufacturer. However, the following method is generally adopted. First, if a signal quality problem of servo information occurs immediately after the servo write process, there is a manufacturer who wishes to vibrate re-servo to make the signal state of the servo information acceptable. (Ie, allowable value), the manufacturer designates the bad servo sector to be bad marking and does not use the bad servo sector so that the bad servo sector is not influenced in the future operation . Second, the problem of servo information corruption can occur in the test process after the basic product completion stage, as well as during normal user drive use. If the servo information is damaged when using the drive, the user must return or discard the product due to the inability to perform the normal read / write operation. That is, in the conventional hard disk drive, if normal servo control can not be performed due to damage or deterioration of the servo information that occurs during use of the drive, there is no countermeasure thereto, and the life of the drive must be terminated.

Accordingly, an object of the present invention is to provide a method of automatically replacing a defective sector in a hard disk drive with a new defective sector.

It is another object of the present invention to provide a method of automatically replacing a corresponding track with a new track when a large number of defective sectors are generated on the same track when a hard disk drive is used.

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

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

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

According to another aspect of the present invention, there is provided a method of automatically replacing a defective sector of a hard disk drive using a disk having a spare track as a recording medium, the method comprising: when a data read / And the servo sector is replaced with a predetermined servo sector existing on the spare track to read / write data.

Hereinafter, an operation according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Many specific details, such as the number of data zones, the number of tracks in each data zone, and the size (bytes) of data sectors, are shown in the following description and drawings to provide a more thorough 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. The detailed description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

FIG. 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 a long disk 10 and six heads 8 corresponding thereto . 2, the microprocessor 2 includes a Programmable Read Only Memory (PROM) 4 storing a predetermined control program of the microprocessor 2, a static random access memory Memory: hereinafter referred to as SRAM) 6. The head 8 is attached to one end of the actuator to perform a horizontal movement on the disk 10, which is a recording medium, and to read and write data on the disk 10. A VCM (Voice Coil Motor) 12 located at the other end of the actuator having the head 8 attached thereto is horizontally driven on the disk 10 in accordance 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 to receive a digital control input signal U from the microprocessor 2 and convert it into an analog signal To the VCM driver (16).

The motor driver 20 is connected to the spindle motor 14 and the microprocessor 2 and controls the operation of the spindle motor 14 under the control of the microprocessor 2. A preamplifier 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 control unit 30 and receives the writing data from the interface control unit 30 under the control of the microprocessor 2 And outputs it to the preamplifier 22. The read / write channel circuit 24 digitally converts an analog reading signal input from the preamplifier 22 and outputs the analog read signal to Encoded Read Data (ERD). An analog-to-digital converter (ADC) 26 is connected to the read / write channel circuit 24, receives an analog servo signal, digitizes the analog servo signal into a PES, and outputs it to the microprocessor 2. The gate array 28 is connected to the read / write channel circuit 24 and receives an ERD signal. The gate array 28 detects servo information such as a servo code of the disk 10 from the ERD signal, do. The interface control unit 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, a practical configuration of the present invention does not require additional hardware or a separate device as a defective servo sector and an embedded servo track automatic replacement part in a drive firmware. However, if a register for storing the servo error code is separately provided after collectively determining the servo error in order to store more detailed contents of the servo error and use it for analysis, the present invention can be implemented more easily. However, it is also possible to use one of the memories (or registers) allocated to the servo control system without any separate storage means, or to store the servo error code using one of the memories allocated to the gate array 28 or the interface control section 30. [

Hereinafter, a case where a defective sector is generated on a predetermined track among the tracks arranged concentrically on the disk 10 and a case where a large number of defective sectors are generated on the same track (hereinafter referred to as a defective servo track) ) Will be described in detail with reference to the replacement of the new servo sector and the replacement of the servo track.

First, FIG. 3 shows an outer zone (OZ), a middle zone (MZ), and an inner zone (IZ) on the disk 10 having the zone layout of FIG. 1 Lt; RTI ID = 0.0 > 1 < / RTI >

As shown in FIG. 1, the basic characteristics of the disk employing the embedded servo sector system are as follows. The number of servo sectors per track is the same regardless of each data zone. However, as shown in FIG. 3, OZ). That is, if there is one data sector per servo sector in the track existing in the middle zone MZ, 1.5 and 0.7 data sectors exist in the outer circumference zone OZ and the inner circumference zone IZ, respectively, per servo sector. Hereinafter, a method of replacing a defective servo track with a new spare track will be described in an embodiment of the present invention.

First, in order to replace a new track when the above-described defective servo track is generated, a spare track is provided on the disk 10 in advance. The easiest and least problematic method for this is to set the entire outermost cylinder of each zone (IZ, MZ, OZ) or one or two tracks to spare. In an embodiment of the present invention, It is assumed that only the outermost tracks are set.

Hereinafter, a method of replacing a defective servo track in a case where servo control is impossible due to the occurrence of a plurality of defective sectors will be described as follows in the data read / write operation.

If a plurality of defective sectors occur on the same track and a normal data write operation is not possible, the microprocessor 2 moves the head 8 to a spare track provided on the zone including the defective servo track, And writes data received from the host computer on the track. Then, the microprocessor 2 stores information about the spare track in the system cylinder and the SRAM 6 provided in the system zone SZ on the disk 10, respectively. The microprocessor 2 then accesses the spare track that has been replaced if it wishes to access the detec servo track.

If the power is "off" or "on ", the microprocessor 2 reads the information about the spare track stored on the system cylinder at the time of replacing the defective servo track after the drive- And loads the SRAM 6 on the SRAM 6 to set a flag indicating that there is replacement information.

As a result, the spare information presence / absence flag for the decovered servo track is checked at each data access, and when the replacement information presence / absence flag is set, track search is performed to the spare track with reference to the replacement information loaded at power on. In this case, although the overhead of the microprocessor 2 may increase, it is less likely to affect the overall performance. Hereinafter, a method of replacing a defective servo track in a case where normal data read operation is impossible due to occurrence of a defective servo track will be described below.

If the position error signal remains at a high level due to the defective servo track during the execution of the data read command, the microprocessor 2 repeats the subroutine for data read retry a predetermined number of times If the data read is not performed even if all of the methods for retrying the data read (for example, the retry subroutine or the ECC) are used, the microprocessor 2 controls the interface control unit 30 The information recorded in the data read error related registers (i.e., task registers and status registers) is analyzed to determine whether or not the de-peg servo track replacement algorithm is applied according to an embodiment of the present invention. If it is determined that the defective servo track should be replaced with a new spare track, the microprocessor 2 sets a track that is currently in the highest priority among the spare tracks, and then reads all data that can be read on the defective servo track .

Thereafter, the microprocessor 2 writes the read data on a data sector mapped to a one-to-one correspondence on the set spare track, and processes the unrecovered data as lost data. Then, the microprocessor 2 can perform the data read operation by checking the replacement information presence / absence flag at each access to the corresponding deck servo track as in the above-described data write operation.

Meanwhile, in the embodiment of the present invention, an alternative method for the de-peg servo track has been described. However, when the de-peg servo sector is generated without any other modification, the new servo sector may be replaced with the new servo sector.

As described above, according to the present invention, when a normal data read / write operation can not be performed due to the occurrence of a defective servo sector in use of a hard disk drive, a preliminarily set spare track or spare sector is mapped on a one to one basis, There is an advantage to be able to.

Claims (5)

A method of automatically replacing a defective sector of a hard disk drive using a disk having a spare track as a recording medium, A step of replacing the corresponding defective sector with a predetermined sector existing on the spare track and recording the data when the defective sector can not be read or written as the defective sector is generated; And And reading / writing the data by accessing the servo sector when accessing the data. The method according to claim 1, Further comprising the step of reading / writing the data by replacing the track with the spare track if the defective sector has occurred on the same track or more than the preset value. 3. The method according to claim 1 or 2, And a replacement sector corresponding to the replacement information is accessed every time the corresponding data is accessed, so that the spare sector corresponding to the defective sector is replaced with the spare sector. And reading / writing data from the defective sector. The method of claim 3, Wherein the servo information recorded on the disk is servo information recorded in an embedded servo sector format. A method for automatically replacing a defective sector of a hard disk drive employing a zone bit recording method having spare tracks for each zone, Replacing the defective sector with a predetermined servo sector on a spare track in the corresponding zone when a data read / write operation is impossible as the defective sector is generated; Recording replacement information for the defective sector on a system cylinder on the disk; And And reading / writing the data by accessing a servo sector corresponding to the loaded alternate information each time the data is accessed.