JP2001176013A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record and reproduce data by previously protecting data from being lost owing to an after-defect on a magnetic disk and the deterioration of performance in a recording and reproducing head, dividing data information into lengths correctable by an error correction code(ECC) in order to improve the data error rate in reproduction and using a plurality of magnetic disks and magnetic heads. SOLUTION: When one piece of information is recorded and reproduced, the information is divided into lengths correctable by the ECC 11 in a data control circuit 6 and recorded and reproduced through the use of >=2 magnetic heads 2 and magnetic disks 1, so that the loss of data information 9, which is generated by the after-defect on the magnetic disk 1 due to an external main cause and also the deterioration of reproduction performance in the magnetic heads 2, is prevented and a data error rate in the case of reproduction is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording / reproducing method for a data recording / reproducing device such as a magnetic disk device.
In particular, error correction code (ECC) for one block of data
The length must be correctable in the above, the recording and reproduction must always be performed using two or more magnetic heads and two or more magnetic disks, and data loss when a subsequent defect on the magnetic disk occurs, The present invention relates to a recording / reproducing method for protecting in advance and an apparatus for implementing the method.

[0002]

2. Description of the Related Art A recording / reproducing operation of a conventional data recording / reproducing apparatus will be described by taking a magnetic disk drive as an example. The magnetic disk device is composed of a magnetic head having an MR head for reproduction and an inductive head for recording, a magnetic disk as a recording medium installed facing the magnetic head, and a recording / reproducing circuit for performing recording / reproducing operation of a data part. Be composed. On a magnetic disk as a recording medium, a recording area called a concentric track is formed. On this track, a servo area intermittently arranged at equal intervals on a circumference and a servo area And a data recording area arranged in the data storage area. The data recording area usually includes a plurality of data sectors, and each data sector is composed of a synchronization pattern, data information, and an error correction code (ECC) for discrimination during normal data reproduction.

A recording / reproducing circuit for performing a recording / reproducing operation of these data portions is constituted by a read circuit, a write circuit, and a data control circuit. The read circuit performs a data section reproducing operation, and the write circuit performs a data section recording operation. When one piece of data information is recorded, the information is usually divided by the data control circuit into a plurality of fixed-length data that have been formatted in advance, a synchronization pattern for discrimination at the time of data reproduction, and an error correction code (ECC). And the data is continuously recorded on the magnetic disk by the write circuit. At the time of reproduction, each data sector is reproduced individually by the read circuit, and restored to the original data information by the data control circuit. With the rapid increase in recording density in recent years, the amount of data allocated to a magnetic disk facing one magnetic head tends to increase. By the way, the surface of the magnetic disk is precisely flattened and a uniform recording film is formed on the surface, but it is not a perfect film, but a part where impurities are mixed or a part where film formation is incomplete, Furthermore, there are portions where dusts and the like are attached to the surface, and it is impossible to perform normal recording and reproduction in these portions. Such a location is called a medium defect location. Normally, the manufacturer detects a known medium defect portion and excludes it as an unused area so that at least at the time of shipment of the magnetic disk device, the medium defect portion does not seem to exist. The magnetic head and the magnetic disk used for recording and reproduction are housed in a sealed case, which is usually free of dust.However, it is very difficult to construct a completely dust-free environment. In the case of long-term use, media defects may occur lately due to dust adhering to the surface of the magnetic disk lately or scratching the surface of the magnetic disk due to contact between the magnetic head and the magnetic disk. It is very difficult to eliminate such a phenomenon. Prior protection measures against late defects on the magnetic disk due to the above factors have become indispensable for improving the data error rate in the recording / reproducing system.

With respect to the data protection method, for example, Japanese Patent Application Laid-Open No. 06-020403 discloses a method in which an error correction code (ECC) is multiplexed and a majority decision circuit is provided to improve the error correction capability.

[0005]

In the recording / reproducing system of the magnetic disk drive, in the conventional method, the data information to be recorded is data having a length of one track or more, or a defect is detected in the track during manufacturing. The data information is divided into a plurality of fixed-length data sectors specified by a higher-level device, except for a special case such as being defined as an unused area. Is generally recorded continuously. However, as the recording density increases, if a wide range of subsequent defects occur on the magnetic disk due to the above reasons, the number of bytes of the unit length increases due to the increase in the recording density. In ECC), an error of an unrecoverable length is generated, and it is highly likely that it is difficult to reproduce the information.

[0006]

In a recording / reproducing system of a magnetic disk drive, after one piece of information is divided into a fixed number of bytes formatted in advance, an error correction code (EC
C) By dividing the data into a plurality of pieces of data in accordance with the correction capability of C), the compatibility with the conventional method is maintained for the host device, the correction capability for each data sector is improved, and the reliability of each data sector is improved. The purpose is to improve.
Further, instead of continuously recording data on one magnetic head and a magnetic disk facing the magnetic head at the same time, by recording data information on a plurality of magnetic heads and magnetic disks, it is possible to avoid the inability to recover data. For the purpose.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of a magnetic disk drive using a conventional recording / reproducing method. First, processing of the recording / reproducing system in the conventional method will be described with reference to FIG. At least one magnetic disk 1 for recording information is mounted on a shaft driven by a spindle motor 4. Magnetic head 2 arranged opposite magnetic disk 1
Is supported by the head support mechanism 3. The head support mechanism 3 is driven by the drive unit 5. By the head support mechanism 3 and the drive unit 5, the magnetic head 2 moves from the outer circumference to the inner circumference of the magnetic disk 1 and in the opposite direction, and is positioned on a target concentric track, thereby performing the information recording / reproducing operation. Do. When recording one piece of data information, the information is first stored in the data buffer 6 and divided by the data dividing circuit (A) 7 into a fixed-byte length already formatted. Thereafter, an error correction code (ECC) and a discrimination information addition circuit 9 are provided by an ECC addition circuit (A) 8.
Thus, a synchronization pattern for discrimination at the time of data reproduction is added, and is recorded on the magnetic disk 1 by the write circuit 10. Further, at the time of reproduction, each data sector is reproduced individually by the read circuit 11, the error correction code (ECC) is corrected by the error correction circuit (A) 13, and the original data information is corrected by the data synthesis circuit (A) 14. Is restored.

FIG. 2 shows an embodiment of a conventional recording / reproducing method. With reference to FIG. 2, a description will be given of a recording / reproducing system process according to a conventional method using, as an example, a case where 1,024-byte data information 15 is recorded / reproduced. In the conventional method, one data information 15 (1024 bytes)
Is recorded, the data information is first stored in the data buffer 6.
And a plurality of fixed-length data information (N) 1 designated by the host device by the data dividing circuit (A) 7.
8 (512 bytes) and data information (N + 1) 19 (5
12 bytes). Next, an error correction code (ECC) 20 is added to each of the divided data by the ECC adding circuit (A) 8, and a data discrimination pattern 16 at the time of reproduction is added by the discrimination information adding circuit 9, respectively. As long as there is no, the normal write circuit 10 continuously records the same magnetic disk (A) 22 continuously. Here, assuming that the correction capability of the error correction code (ECC) 17 is a maximum of 32 bytes, a defect (A) 23 occurs in the area of the magnetic disk (A) 22 where the data information (N) 20 is recorded. In this case, if the defect (A) 23 is 32 bytes or less, the data information (N) 18 can be corrected by the error correction code (ECC) 17, so that the original data information 15 can be restored. However, when the defect (A) 23 is 33 bytes or more, it is difficult to correct the data information (N) 18 by using the error correction code (ECC) 17. 15 cannot be restored.

FIG. 3 is a block diagram of an embodiment of a magnetic disk drive according to the recording / reproducing method according to the present invention. First, the processing of the recording / reproducing system according to the conventional method will be described with reference to FIG.
When recording one piece of information, the information is first stored in the data buffer 6 and divided into a fixed byte length already formatted by the data dividing circuit (A) 7,
Error correction code (ECC) by additional circuit (A) 8
Is added. Next, the data dividing circuit (B) 24
It is divided into a length that can be corrected by the error correction code (ECC), the error correction code (ECC) is added again by the ECC addition circuit (B) 25, and then the data is continuously written on the same magnetic disk by the rearrangement circuit 26. The divided data is rearranged so as not to be recorded. Thereafter, a synchronization pattern for discrimination at the time of data reproduction is added by the discrimination information addition circuit 9, and is recorded on the magnetic disk 1 by the write circuit 10. At the time of reproduction, each data sector is reproduced individually by the read circuit 11, and the rearrangement circuit 27
Thus, the data is rearranged in the order of the original data information, the error correction circuit (B) 28 corrects the error for each data sector, and then the fixed byte length formatted by the data synthesis circuit (B). Is synthesized. Further, the error correction circuit (A) corrects the error of the synthesized data, and the data synthesis circuit (A) 14 restores the original data information. The additional circuits according to the invention are the parts indicated by 24-26 and 27-29 in FIG.

FIG. 4 shows an embodiment of the recording / reproducing method according to the present invention. Referring to FIG. 4, the processing of the recording / reproducing system in the method according to the present invention will be described using the case of recording and reproducing 1,024-byte data information 30 as in the conventional method. In the recording / reproducing system according to the present invention, when one data information 30 (1024 bytes) is recorded, the data information is first stored in the data buffer 6 and then the data dividing circuit (A) 7 as in the conventional system. , A plurality of fixed-length data information (N) 32 already formatted
(512 bytes) and data information (N + 1) 33 (51
2 bytes). This is for the purpose of maintaining compatibility with the conventional system as viewed from the host device and the purpose of reducing the load on the processing system of the host device. Further, only the error correction code (ECC) 31 is added to each divided data information by the ECC adding circuit (A) 8, and these are referred to as data information (N) 34 and data information (M) 35, respectively. Assuming that the length of the error correction code (ECC) itself is 64 bytes, the data information (N) 34 and the data information (M) 3
5 is 576 bytes each. In the example, since the error correction code (ECC) has a maximum correction capability of 32 bytes, the data information (N) 34 is divided into 18 blocks of data information of 32 bytes each, ECC for data information
The error correction code (EC) is added by the additional circuit (B) 25.
C) 37 is added, and the rearrangement circuit 26 rearranges the divided data so as not to be continuously recorded on the same magnetic disk. Thereafter, the discrimination information addition circuit 9
Accordingly, a synchronization pattern 36 for discrimination at the time of data reproduction is added. These divided data are referred to as data information (n) 38 to data information (n + 17) 55. Further, the data information (n) 38 to the data information (n + 17) 55 are written not only by the magnetic disk (A) 21 but also by the write circuit 12 according to the arrangement given by the rearrangement circuit 26.
The information is recorded by being alternately arranged on the magnetic disks (B) 56 to 58 (D). At the time of reproduction, the divided data arranged on each magnetic disk is reproduced alternately by the read circuit 11, and returned to the original order by the rearrangement circuit 27.

Thereafter, error correction is individually performed using the error correction circuit (B) 28, and the data synthesis circuit (B) 29
Is combined with the 576-byte data information (N) 34 and the data information (M) 35 to which the format designation 512 bytes and the error correction code (ECC) 31 for the 512-byte data are added. Next, the error correction circuit (A) 13 performs error correction on each of the 512-byte data information, and the data recovery circuit (A) 14 recovers the original 1,024-byte data information 30. Here, in the conventional method, a method of avoiding a defect in the present invention when a subsequent defect of 33 bytes or more occurs as in the case where the original data information 15 cannot be restored is described. First, when a defect of two blocks occurs on one magnetic disk (A) 22 as in the case of the defect (B) 59 in FIG. 4, the data information (n) 38 has an error correction code (EC).
C) Since the defect reaches the 37th part, reproduction becomes difficult, but the data information (n + 7) 45 can be corrected by the error correction code (ECC) 37. Therefore, it is difficult to reproduce only the 32 bytes allocated to the data information (n) 38 out of the original 1,024 bytes of the data information, but this is restored to the 512-byte data information (N) 32. In this case, the error can be corrected by the error correction code (ECC) 31 added to the data information (N) 32. As a result, the original 1024-byte data information 30 can be restored.

If two or more blocks after the subdivision are completely covered with defects, restoration becomes difficult, but the rearrangement circuit 26
Therefore, such a state is hard to imagine because the arrangement is such that recording is not performed continuously. Furthermore, even when almost the entire area of one track is covered with a defect, the possibility of covering the fragmented data with the defect is low due to the method of dividing and recording data on a plurality of magnetic heads and magnetic disks. There is no problem in restoring data. If a defect occurs at the same physical location on a plurality of magnetic disks, the rearrangement circuit 26 performs a physically different arrangement for each block on the magnetic disk. It seems that there is almost no problem in restoring the data.

Therefore, the data information of each block recorded using the method according to the present invention can be corrected by an error correction code (ECC) in most cases except for the rare cases as described above. For this reason, the original data information 30 can be restored without being affected by a subsequent defect on the magnetic disk, and the data error rate at the time of reproduction can be reduced and reliability can be improved.

[0015]

According to the present invention, in a recording / reproducing system of a magnetic disk device, data loss due to a late defect on a magnetic disk is protected beforehand, a data error rate at the time of reproduction is reduced, and reliability is improved. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an information recording / reproducing system of a magnetic disk device according to a conventional method.

FIG. 2 is a diagram showing an example of data loss according to a conventional method.

FIG. 3 is a diagram showing an embodiment of an information recording / reproducing system of the magnetic disk device according to the present invention.

FIG. 4 is a view for explaining an effect of improving reliability by the present method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Magnetic head, 3 ... Head support mechanism, 4 ... Spindle motor, 5 ... Drive part, 6 ... Data buffer, 7 ... Data division circuit (A), 8 ... ECC addition circuit (A), 9 ... discrimination information addition circuit, 10 ... light circuit,
11: Read circuit, 12: Data discrimination circuit, 13: Error correction circuit (A), 14: Data synthesis circuit (A), 15:
Data information, 16: Discrimination pattern, 17: ECC, 18
... data information (N), 19 ... data information (N + 1), 20 ...
Data information (N), 21 Data information (N + 1), 22 Magnetic disk (A), 23 Defect (A), 24 Data division circuit (B), 25 ECC addition circuit (B), 26 ... Arrangement circuit, 27 ... Arrangement circuit, 28 ... Error correction circuit (B), 29 ... Data synthesis circuit (B), 30 ... Data information, 31 ... ECC, 32 ... Data information (N), 33 ... Data information (N + 1), 34 ... data information (N), 35 ... data information (M), 36 ... discrimination pattern, 37 ... ECC, 3
8 ... data information (n), 39 ... data information (n + 1), 40
... data information (n + 2), 41 ... data information (n + 3), 42
... Data information (n + 4), 43 ... Data information (n + 5), 44
... data information (n + 6), 45 ... data information (n + 7), 46
... data information (n + 8), 47 ... data information (n + 9), 48
... Data information (n + 10), 49 ... Data information (n + 11), 5
0: data information (n + 12), 51: data information (n + 13),
52: Data information (n + 14), 53: Data information (n + 1)
5), 54 ... data information (n + 16), 55 ... data information (n
+17), 56: magnetic disk (B), 56: magnetic disk (C), 58: magnetic disk (D), 59: defect (B).

Claims (2)

[Claims] At least one magnetic disk in which a data area for storing data and a servo area for storing position information are alternately arranged on a disk surface, and one or more magnetic disks are arranged as a pair facing the magnetic disk surface. A series of data strings into one or more blocks,
In a data recording / reproducing apparatus including a recording unit that stores a plurality of blocks on a recording medium at a certain block interval and a reproducing unit that reproduces a data string from the recording unit in units of the blocks, one block of data is A magnetic disk drive, wherein the length is limited to a length that can be corrected by an error correction code (ECC). 2. One or more magnetic disks in which a data area for storing data on a disk surface and a servo area for storing position information are alternately arranged, and a pair of magnetic disks are arranged opposite to the magnetic disk surface. A series of data strings into one or more blocks,
In a data recording / reproducing apparatus including a recording unit that stores a plurality of blocks on a recording medium at a certain block interval and a reproducing unit that reproduces a data string from the recording unit in units of the block, one piece of data information is always stored. A magnetic disk device that performs recording and reproduction using two or more magnetic heads and a magnetic disk.