JPH0620403A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the read error ratio by using the read Solomon code as information for detection and correction of data read error multiplexing a correction code and providing a majority circuit of read error correction code information. CONSTITUTION:A central processing means 7 sets the number of read sectors and a pointer indicating the buffer storage position of read data and sets a retry count to a retry counter. The cylinder number, the head number, the sector number, and flag information of the ID part are set to an HDC 6 to start the read operation. The HDC 6 reads in the recorded signal of a recording medium 2 through a discriminator 5 to perform ID comparison. When ID error is detected, retry is started; and if ID information is not found or error is not recovered before the retry counter reaches 0, the processing is terminated with error. The means 7 checks the ECC status of an ECC circuit 9 due to the read Solomon code after the end of read and uses a majority circuit 10 for sector data in a buffer 8 to perform the error processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device used as a storage device for a computer or the like, and more particularly to a small size and high capacity magnetic disk device.

[0002]

2. Description of the Related Art In recent years, in magnetic disk devices, small slider thin film magnetic heads have been introduced, high smoothness magnetic recording media have been developed,
Technological innovations such as performance improvement of precision positioning servo technology and evolution of signal processing / modulation method have occurred one after another, and its performance and recording density per unit area have improved remarkably.

Further, the trend toward miniaturization due to these technological innovations is also rapidly advancing, and those having a size of 3.5 inches to 2.5 inches, and recently less than 1.8 inches are emerging. However, in such a small-sized magnetic disk device, the recording density per unit area becomes very high, so that the S / N ratio of the reproduced signal becomes low, and the existence of magnetic defects on the magnetic recording medium cannot be ignored.

Therefore, in order to improve the reliability of the data read / written even if there is a defect on the magnetic recording medium, the slur correction process and the data format have become important.

The operation of the conventional magnetic disk device including the data format and error correction processing will be described below by taking the reproduction of data on the recording medium as an example.

FIG. 5 is a block diagram showing the configuration of a signal processing system of a conventional magnetic disk device. Reference numeral 1 denotes the whole magnetic disk device in the dotted line, 2 a magnetic recording medium in which data is stored, 3 a data head for writing and reading data on the magnetic recording medium 2, and 4 a data head 3 For amplifying the signal of 5
A discriminator for binarizing the output of the HDD, 6 is an HDC (hard disk controller) for capturing the signal at the time of reading and controlling the output of the write signal at the time of writing in accordance with a predetermined data format, and 7 is an HDC
Central processing means for controlling the DC 6, 8 is a buffer that stores the data taken in the HDC 6 when reading from the magnetic recording medium 2, and a buffer that stores the data that is written through the HDC 6 when writing to the magnetic recording medium 2, 13
An ECC circuit for detecting the occurrence of a read error in read data and correcting the error usually uses a computer-generated code of 32 bits or 56 bits in many cases. Reference numeral 11 denotes an interface, which transmits and receives data to be read and written between an external host device described later and the magnetic disk device 1 via the buffer 8. Reference numeral 12 denotes an external host device, which is an information processing device body that operates the magnetic disk device as an external storage device, and is not included in the configuration of the magnetic disk device.

The format will be described. In the magnetic disk device, the data record is 256 bytes,
Recording / reproducing is performed in a unit of a fixed small block of 512 bytes and 1024 bytes, and the unit is called a sector. An ID portion as header information, ECC information for error correction, etc. are added to this sector, and a plurality of tracks are sequentially allocated to tracks arranged concentrically on a magnetic recording medium. Normally, several tens of sectors are arranged on one track.

FIG. 6 shows an example of a conventional format.
In FIG. 6, 14 and 15 are tracks T and T + 1 formed concentrically on the magnetic recording medium 2. Here, the nth sector 22 on the track T is described. The sector 22 is divided into an ID section 16, a data section 17, and an error correction code section 18. 101 is PLO
(Phase Locked Osillator) 9 bytes, 102 SY
1 byte in NC (Synchronization Byte), 103 is I
6 bytes for D data (Identity Data Field), 104
Is 2 bytes for CRC (Cyclic Redundancy Code), 10
5 is 2 bytes for PAD, 106 is 2 bytes for SPLICE, 107 is 9 bytes for PLO, 108 is 1 for SYNC
Byte, 109 is a data field, 256 or 5
12 or 1024 bytes, 115 is ECC (Error Co
rrection code) 4 or 7 bytes, 113 is PAD
Is 2 bytes, and 114 is 2 bytes in SPLICE.
The number of bytes and the order of formats described here can be arbitrarily changed. The purpose of each information is explained below. Normally, the pulse discriminator 5 is provided with a data discrimination window of a predetermined width for a bit string recorded on a recording medium at the time of reading out data, and if there is a magnetization reversal in this discrimination window, information of 1 is obtained, and 0 if not. It is determined that. Therefore, in order to read information without error, a VCO (Voltage Control Osci) is read within a predetermined time in the reproduction bit string of the discrimination window including the rotation fluctuation of the spindle motor.
llater) must follow. For this purpose, PLO 101 and 107 are provided at the beginning of the ID information and DATA information in the format so that the reproduced bit string of the discrimination window can be followed within the time of PLO 101 and 107. The SYNCs 102 and 108 are used to distinguish the PLO 101 and 107 from the ID information and DATA information that follow. The ID data 103 indicates where on the recording medium the sector to be recorded and reproduced is assigned. Information for indicating the attribute of the sector may be recorded in this portion during recording and reproduction. The CRC 104 adds read error detection information generated from the SYNC 102 and the ID data 103, and is for detecting a read error in the HDC 6 at the time of reading. PAD 105 and 113
If, for example, the (2,7) modulation method is used as the data recording method, conversion cannot be performed until the final bit of the data depending on the data pattern, so conversion cannot be performed. Therefore, add 1 byte so that conversion is possible. It is what If it takes longer time than normal due to fluctuations in the rotation of the motor during the writing operation to the ID section 16 or the previous sector, if there is no SPLICE 106 and 114, then the next PLO 101 or 107 is arranged. Also, the data is not recorded correctly, and the VCO cannot sufficiently follow the reproduction bit string of the discrimination window, which is the role of the PLO 101 or 107, and the data cannot be reproduced correctly. Therefore, the SPLICEs 106 and 114 are arranged to absorb the time variation. The ECC 115 adds the detection error correction information of the read error of the SYNC 108 and the data field 109 as a redundant bit, and the ECC data generated by the ECC circuit 13 at the time of reading and the E read from the recording medium.
This is for detecting / correcting a data read error by comparing with CC115.

According to the above data format,
The process of recording and reproducing on the recording medium is performed according to the procedure programmed by the central processing means 7.
The HDC 6 controls.

The data reproducing process and the error processing operation of the conventional magnetic disk device will be described below with reference to the flowchart of FIG. 7 by taking data reading as an example. As the initial setting, the central processing means 7 sets a pointer indicating the read sector number and the buffer storage position of the read data, and sets the retry count in the retry counter (201). The HDC 6 is set with the cylinder number, head number, sector number, and flag information of the ID section which is the header information of the read sector, and the HDC 6 is made to start the read operation (202). The HDC 6 instructs the read mode to the circuit of the signal processing system, and the magnetic recording medium 2
The signal recorded in 1 is taken in from the data head 3 through the amplifier 4 and the pulse discriminator 5. Thus HD
C6 starts reading the data of the current track on the disc, and starts comparing the ID information whether the ID information of the corresponding sector exists on the track. Read ID
The disc is 1 while the information is different from the ID information of the target sector.
When it is detected that it has rotated (203) or when an error in the ID information is detected by the CRC provided for error detection (205), 1 is subtracted from the initially set retry counter (206), Retry is started (207). If the retry counter reaches 0,
If the ID information you are looking for is not found on the current track,
If the error detected by the CRC is not recovered, the process ends in error (208).

When the ID information of the target sector is found (204), it is judged that the signal of the subsequent data field 109 is data, the pointer is incremented in the buffer 8 and read, and the reading is performed. Start. Reading is performed for the number of data in one sector and the subsequent E
Performed for the total number of CC bytes (2
09). In this way, the sector data for one sector is stored in the buffer 8, and the reading for one sector is completed.

Further, after the reading of the sector data for one sector is completed, the central processing means 7 checks the ECC status of the ECC circuit 13 to check whether or not an error has occurred in the read sector data ( Two
10). If an error occurs, the central processing means 7 uses the ECC circuit 13 to detect the position of the error and the error bit length (211). Since the error correction is possible if the error bit length is within a certain length, the central processing means 7 also performs error correction processing on the sector data in the buffer 8 (212). When it is determined that it is impossible, the central processing means 7 terminates the reading of the sector in error (208).

Thus, when the reading of one sector is completed, the HDC 6 decrements the initially set number of read sectors and increments the sector information of the ID section,
The 1-sector read process is restarted and repeated until the number of read sectors becomes 0, and the read process is completed (2
13).

At this time, the central processing means 7 simultaneously sends out the read data through the interface 11 while sequentially monitoring the state of the external host device 12 and handshaking the read data. If an unrecoverable read error occurs on the way, the central processing means 7 transmits the error status to the external host device 12 and stops the read process on the way.

[0015]

In the above conventional example, the EC
It was designed by considering that the frequency of occurrence of an error in a data portion having a long error burst length, which makes it impossible to correct an error by C, is very low. Moreover, even if an error occurs, it can be dealt with sufficiently by re-reading it again by retrying. However, in recent magnetic disk devices, the capacity has been increased, and both the track density and the linear recording density have been significantly increased. Therefore, for example, the Reed-Solomon code, which is a stronger error correction code than the conventional computer-generated code, is used for the error correction of the data portion.
The design is changing on the premise that a read error will occur due to a decrease in / N.

However, if a read error occurs in the error correction code itself, it becomes impossible to accurately detect the error position and the error burst length by the error correction code. Therefore, when the error that occurred in the read data is corrected, the error and error are corrected and the read data is destroyed.

As described above, the Reed-Solomon code or the like is used as the correction code in order to cooperate with the error correction. However, these error correction codes need to increase redundancy with respect to the number of data in the data field. For this reason, the code length is relatively long, and therefore the error occurrence frequency of the error correction code itself is increasing.

If error correction of data occurs due to a read error of the error correction code itself, an external host device that instructs the magnetic disk device to read and write data will take in the erroneous data as correct data. There was a big challenge.

The present invention solves the above problems, and an object of the present invention is to provide a magnetic disk device having a small read error rate.

[0020]

In order to achieve the above object, the present invention employs a Reed-Solomon code correction method as an ECC error correction method for a data section, and a plurality of error correction codes. After recording and reading, it has a configuration including a majority decision circuit that adopts one of a plurality of error correction code data, which has the same data as the correct one, as correct.

[0021]

According to the present invention, since the Reed-Solomon code, which is a strong error correction method, is adopted by the above-described structure, the error rate after correction can be reduced, and if a part of the error correction code itself is defective in the magnetic recording medium. , Or even if a read error occurs due to a decrease in S / N, the majority-correction circuit adopts the more correct error-correction code data, thus reducing error correction errors.

[0022]

1 is a block diagram showing the configuration of a signal processing system of a magnetic disk device according to an embodiment of the present invention. Reference numeral 1 denotes the whole magnetic disk device in the dotted line, 2 a magnetic recording medium on which data is recorded, 3 a data head for writing and reading data on the magnetic recording medium 2, and 4 a data head 3 , 5 is a pulse discriminator for binarizing the output of the amplifier 4, 6 is an HDC for capturing the signal at the time of reading and controlling the output of the write signal at the time of writing according to a predetermined data format, Reference numeral 7 is a central processing means for controlling the HDC 6, and 8 is an HD when reading from the magnetic recording medium 2.
This is a buffer that stores the data taken into C6 and stores the data to be written through the HDC 6 when writing to the magnetic recording medium 2, and is the same as the conventional example so far.

Reference numeral 9 denotes an ECC circuit for detecting the occurrence of a read error in the read data and correcting the error.
A Reed-Solomon code having a bit length of 8 bits or more is used. An error correction code data majority decision circuit 10 will be described later. 11 is an interface, and a buffer 8
Data to be read from and written to an external host device to be described later is transmitted and received via the. Reference numeral 12 denotes an external host device, which is an information processing device body that operates the magnetic disk device as an external storage device, and is not included in the configuration of the magnetic disk device.

FIG. 2 shows an example of the format in one embodiment of the present invention. In FIG. 2, reference numerals 14 and 15 denote tracks T and T formed concentrically on the magnetic recording medium 2.
+1 and here is the n-th sector 2 on the track T.
2 is explained. The sector 22 is divided into an ID section 16, a data section 17, and an error correction code section 18,
The error correction code section 18 is further divided into first error correction code information 19, second error correction code information 20, and third error correction code information 21.

[0025] 101 is a PLO 9 bytes, 102 is SY
NC is 1 byte, 103 is ID data 6 bytes, 10
4 is CRC 2 bytes, 105 is PAD 2 bytes, 1
06 is 2 bytes in SPLICE, and up to here is the ID section 16
Are configured.

Reference numeral 107 is a PLO, which is 9 bytes, and 108 is SY.
NC is 1 byte and 109 is a data file, which is 256, 512 or 1024 bytes, and these constitute the data part.

Reference numeral 110 is a first error correction code (ECC) using an 88-bit Reed-Solomon code, 11 bytes, 111 is a second error correction code, 11 bytes, and 112 is a third error correction code. Similarly, 11 bytes, 113 is 2 bytes in PAD, 114 is SPLICE
Is 2 bytes, and these form the error correction code unit 18. The number of bytes and the order of formats described here can be arbitrarily changed. The meaning of each piece of information is as described in the conventional example.

According to the above data format,
The process of recording and reproducing on the recording medium is performed according to the procedure programmed by the central processing means 7.
The HDC 6 controls.

FIG. 3 shows an example of the error correction code data majority decision circuit in this embodiment. In FIG. 3, 301 is the first
First register for storing the error correction code information of
Reference numeral 02 denotes a second register in which the second error correction code information is stored, 303 is a third register in which the third error correction code information is stored, and these are incorporated in the ECC circuit 9. Here, the registers are shown only for 8 bits, but in reality, they are prepared according to the error correction code length. Reference numeral 10 is a majority decision circuit, the inside of which is 305, 3
AND elements shown in 07 and 309 and 306 and 308,
It is composed of an OR element 310. However,
Shows only three bits, but the remaining bits have the same structure and are omitted. The error correction code data majority circuit will be described below.

The majority decision circuit is a logic which, when the outputs of a plurality of logics do not coincide with each other, adopts the data having the larger number of coincidences. In this case, either the first register, the second register, or the third register outputs the bit at the same position, which is 0 or 1, whichever is greater. For example,
If the least significant bit of each register is a combination of 0, 0, 1 or 0, 1, 0, etc., 0 is output and 1,
If it is 1,0 or 0,1,1, etc., 1 is output. Of course, if all match, the matched value is output. The corresponding logic is A of 305, 307, 309 shown in FIG.
It can be realized by an ND element and an OR element shown by 306, 308 and 310, and the majority circuit 10 is configured by aligning this logic for desired bits.

The data reproducing process and its error processing operation in this embodiment will be described below with reference to the flow chart of FIG. 4 by taking data reading as an example. As the initial setting, the central processing means 7 sets a pointer indicating the read sector number and the buffer storage position of the read data, and sets the retry count in the retry counter (301). The HDC 6 is set with the cylinder number, head number, sector number, and flag information of the ID section that is the header information of the read sector, and the HDC 6 is made to start the read operation (302). The HDC 6 commands the read mode to the circuit of the signal processing system, and takes in the signal recorded on the magnetic recording medium 2 from the data head 3 through the amplifier 4 and the pulse discriminator 5. Thus, HDC
6 starts reading the data of the current track on the disc, and starts comparing the ID information as to whether or not the ID information of the corresponding sector exists on the track. Read ID
The disc is 1 while the information is different from the ID information of the target sector.
When it is detected that it has rotated (303) or when an error in the ID information is detected by the CRC provided for error detection (305), the retry counter that is initially set is decremented by 1 (306), Retry is started (307). If the retry counter reaches 0,
If the ID information you are looking for is not found on the current track,
If the error detected by the CRC is not recovered, the process ends in error (308).

When the ID information of the target sector is found (304), it is determined that the signal of the subsequent data field 109 is data, the pointer is incremented in the buffer 8 and read, and the data is read. Start. Reading is performed for the total number of bytes of the data number of one sector and the following three ECC byte numbers (309). In this way, the sector data for one sector is stored in the buffer 8, and the reading for one sector is completed.

Further, after the reading of the sector data for one sector is completed, the central processing means 7 checks the ECC status of the ECC circuit 9 based on the Reed-Solomon code to check whether an error has occurred in the read sector data. Is checked (310). If an error occurs, the central processing means 7 uses the ECC circuit 9,
Detect the error position that occurred and the length of the error bit (3
11). Since the error correction is possible if the error bit length is within a certain length, the central processing means 7 performs error correction processing on the sector data in the buffer 8 (31).
2). If it is determined that the error bit length is long and the error cannot be corrected, the central processing means 7 terminates the reading of the sector due to an error (308).

Thus, when the reading of one sector is completed, the HDC 6 decrements the initially set number of read sectors and increments the sector information of the ID section,
The 1-sector read process is restarted, and the read process is completed until the number of read sectors becomes 0 (3
13).

At this time, the central processing means 7 simultaneously sends the read data through the interface 11 while monitoring the state of the external host device 12 and sequentially handshaking the read data. If an unrecoverable read error occurs on the way, the central processing means 7 transmits the error status to the external host device 12 and stops the read process on the way. Regarding the data reading of the data field, the Reed-Solomon code of 88 bits or more is adopted to detect the ECC error, and the stronger ECC
Error detection and correction are being performed. Further, the ECC circuit 9 is configured to read the three ECC bytes existing in the sector, use the majority circuit 10 to allow an error in the ECC data, and correctly perform the error correction recovery process.

As described above, according to the present invention, a Reed-Solomon code having a long code length is adopted as an error correction code which is important as information for improving the reading reliability of sector data, and a read error of code information having a long code length is adopted. In order to eliminate the risk of data error correction due to the above, since the majority information circuit is provided to multiplex the code information and to allow the read error of the code information, the reliability of the sector data can be greatly improved compared with the conventional one. .

In the present embodiment, the multiplexing of error correction codes has been described, but it is also possible to multiplex other portions of the sector data such as ID data of the ID section. Further, in the present embodiment, three multiplexing is performed, but it goes without saying that another number may be used.

[0038]

As is apparent from the above embodiments, according to the present invention, the Reed-Solomon code is used as the information for detecting and correcting the data reading error in the reading and writing of data in the magnetic disk device, and the most important information. Since a majority circuit for reading error correction code information is provided by multiplexing the correction code which is the above, it cannot be ignored due to the increase in the linear recording density and the track density accompanying the miniaturization of the magnetic disk device and the increase in the recording density. Also, even when a defect on the magnetic recording medium or a data read error due to a decrease in S / N occurs in the error correction code unit itself, the occurrence of error detection errors and error correction errors is reduced, and which part of the sector It is possible to provide a magnetic disk device capable of maintaining high reliability of read data even if an error occurs in the disk.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a signal processing system of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a data format in the same device.

FIG. 3 is a block diagram showing a configuration of a data voting circuit in the same device.

FIG. 4 is a flowchart of a data reading operation procedure in the same device.

FIG. 5 is a block diagram showing a configuration of a signal processing system of a conventional magnetic disk device.

FIG. 6 is an explanatory diagram of a data format of a conventional magnetic disk device.

FIG. 7 is a flowchart of a data reading operation procedure of a conventional magnetic disk device.

[Explanation of symbols]

 2 magnetic recording medium 6 hard disk controller (HDC) 9 ECC circuit 10 majority circuit

Claims (5)

[Claims] 1. A rotating magnetic recording medium in which a plurality of tracks having a plurality of sectors are formed, a disk controller for controlling recording and reproducing of information on the magnetic recording medium, an error correction circuit for reproducing information, and a plurality of The sector is provided with a majority decision circuit for error correction information, and the sector is provided with an ID section in which ID information as header information of the sector is written, a data field for reading and writing data in the sector, and a plurality of identical error correction information following the data. A magnetic disk device having a data format including an error correction code part. 2. The magnetic disk drive according to claim 1, wherein the sector has a data format in which a plurality of error correction code portions are sequentially and repeatedly written after the data field. 3. The magnetic disk device according to claim 1, wherein the majority decision circuit comprises a plurality of registers for storing a plurality of read error correction information, and a logic in which AND elements and OR elements are combined. 4. The magnetic disk device according to claim 1, wherein a Reed-Solomon code is used as the error correction code. 5. The magnetic disk drive according to claim 1, wherein the data format is such that a PAD section, a PLO section, a SYNC section, and error correction information are sequentially and repeatedly written after the data field, and finally a PAD section and a SPLICE section are provided.