JP2000149462A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device that can enhance the error recovery perfor mance by an error recovery means performed on the occurrence of an error, and also can shorten the error recovery processing time. SOLUTION: An error recovery condition having high error recovery effect is selected from error occurrence conditions and a judging result of a cause of an error (step S1), and recovery means are performed from an error recovery means having a high error recovery rate out of selected error recovery means (step S2). After performing error recovery processing, by preserving an error recovery processing result (step 8), the priority of performing an error recovery means having high error recovery effect is made high and the priority of performing an error recovery means having low error recovery effect is made low, next, when error recovery processing is performed in the same condition, it is performed from an error recovery means having high error recovery effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly to a magnetic disk drive capable of recovering from an error when an error occurs.

[0002]

2. Description of the Related Art When recovering an error in a conventional magnetic disk drive, particularly, a magnetic disk drive whose purpose is mainly to save data of a computer, priority is given to ensuring data reliability. When an unrecoverable error occurs due to the error correction code, the data is read again to recover the error.
Here, when the error recovery processing is performed, in order to reduce the occurrence of errors, the error recovery is performed by changing various conditions on the magnetic disk device.

In a conventional magnetic disk drive, processing is performed in which all recovery means considered to be effective in recovering an error are sequentially executed, so that the error recovery processing takes time. Therefore, when video and audio are recorded as data on the magnetic disk, the reproduced video and audio are interrupted. For this reason, there is a demand for an error recovery means that completes the error recovery processing within a certain time.

[0004] In order to meet this demand, the means disclosed in the following patent publications have been proposed as means for reducing the time required for error recovery processing. 1) In Japanese Patent Application Laid-Open No. 1-285078, when the error recovery means succeeds, the error recovery means that succeeds is stored, and when reading is performed in the same place, the error recovery is successful. It has been proposed that error recovery processing be deleted by using recovery means. 2) Japanese Patent Laid-Open No. Hei 10-134528 has a plurality of groups of error recovery means, detects an error occurrence factor, selects one of the groups according to the content thereof, and performs error recovery processing. It has been proposed.

[0005]

The conventional error recovery means, in which all conceivable error recovery means are sequentially implemented, has a problem that it takes a long time for error recovery processing. Further, at this time, there is also a problem that effective error recovery means cannot be implemented in a case where all error recovery means cannot be implemented because time is not required for error recovery processing. In addition, Japanese Patent Laid-Open No.
The invention disclosed in Japanese Patent No. 078 is effective when an error occurs again at the same place for the same cause, but has a problem that the error cannot be recovered when an error occurs due to a different error factor from the previous one. Also, when an error occurs at a place where no error has occurred before, the same problem as described above occurs. On the other hand, the invention disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-134528 has a problem that the error recovery processing may take a long time in the processing within the group because the error recovery means is sequentially performed. The same problem occurs when the cause of the error is not specified.

Accordingly, the present invention improves the error recovery performance by effectively performing error recovery processing when an error occurs in data on a magnetic disk, and shortens the time required for error recovery processing. Can be
An object of the present invention is to provide a magnetic disk drive capable of improving data throughput performance.

[0007]

In order to solve the above problems, according to the first aspect of the present invention, a circuit capable of determining an error occurrence factor when an error occurs (for example, mainly a microcomputer 8 in the embodiment) (For example, step S1 in the embodiment), and based on the determination result of the error occurrence factor and the condition when the error occurs,
It has an error recovery processing executing means (for example, step S4 in the embodiment) for selecting a plurality of error recovery means (for example, step S2 in the embodiment) and performing the error recovery processing, and has performed the error recovery processing. It has an error recovery processing result storage unit (for example, step S8 in the embodiment) for storing the result.

With this configuration, in performing the error recovery processing, an appropriate error recovery means is selected from the determination result of the error occurrence factor and the condition when the error occurs, and the error recovery means is selected by the selected error recovery means. After the processing is performed, the result of the error recovery processing performed by the performed error recovery unit is updated and stored by the error recovery processing result storage unit. The invention described in claim 2 is characterized in that the error recovery means can be selected according to the result of implementing the past error recovery means in claim 1. With this configuration,
When the error recovery processing is performed by the same error occurrence condition and the same error factor, the error recovery means is selected and performed based on the result updated by the previous error recovery processing. Therefore, an error recovery process appropriate for the error occurrence condition and the cause of the error can be performed first from the recovery means having a high error recovery effect.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a magnetic disk drive 1 according to an embodiment of the present invention. This magnetic disk device 1
Are a magnetic disk 2, a magnetic head 3, a magnetic circuit 4, a read / write circuit (hereinafter referred to as a read / write circuit) 5, a positioning control circuit 6, a signal modulation / demodulation circuit 7, a microcomputer 8,
And a disk control circuit 9. Data written to the magnetic disk device 1 is transmitted to the disk control circuit 9.
Receives data from a higher-level device, and receives a signal
Supplied to The signal modulation / demodulation circuit 7 supplies a signal modulated to a signal suitable for magnetic recording to the read / write circuit 5, which drives the magnetic head 3 and writes data on the magnetic disk 2.

Here, before data is written, the magnetic head 3 is positioned at a predetermined position on the magnetic disk 2. This is because a positioning signal written in advance on the magnetic disk 2 is read by the magnetic head 3 and supplied to the read / write circuit 5, amplified by the read / write circuit 5, demodulated by the signal modulation / demodulation circuit 7, and positioned. This is supplied to the control circuit 6, and the positioning control circuit 6 drives the magnetic circuit 4 by the positioning signal to position the magnetic head 3 at a predetermined position on the magnetic disk 2.

When data written on the magnetic disk device 1 is reproduced, the same positioning control is performed as when writing data, and the magnetic head 3 is positioned at a predetermined position on the magnetic disk 2. Thereafter, the magnetic head 3 reproduces data on the magnetic disk 2 and supplies the data to the read / write circuit 5. The read / write circuit 5 amplifies the reproduced signal and supplies it to the signal modulation / demodulation circuit 7. The signal modulation / demodulation circuit 7 demodulates the data from the reproduced signal to thereby restore the original data to the disk control circuit 9.
Supply to The disk control circuit 9 supplies the reproduction data to a higher-level device. The microcomputer 8 supplies an instruction for a control operation to the positioning control circuit 6 and the disk control circuit 9 when performing the data write and read processing.

At this time, if an error occurs in the reproduced data, the microcomputer 8 performs a recovery processing operation for the error. Here, the positioning control circuit 6 supplies error or warning information relating to positioning, and the read / write circuit 5 and the signal modulation / demodulation circuit 7 supply error or warning information of reproduced data to the microcomputer 8. Disk control circuit 9
When the reproduction data supplied from the signal modulation / demodulation circuit 7 has an error, the reproduction data is corrected using the error correction data in the reproduction data. Here, the disk control circuit 9
Supplies error occurrence information to the microcomputer 8 when an error in the reproduction data cannot be corrected. When an error that cannot be corrected by the disk control circuit 9 occurs in the reproduced data, the microcomputer 8 performs a read operation of the reproduced data to read the correct reproduced data again. At this time, in order to reduce the frequency of occurrence of errors at the time of rereading, the microcomputer 8 performs rereading while executing a plurality of error recovery means until no error occurs.

The operation of this embodiment will be described below with reference to the flowchart of FIG. When an error that cannot be corrected by the disk control circuit 9 occurs in the reproduced data of the magnetic disk 2 to be reproduced, the microcomputer 8 starts a reread operation of the reproduced data (starts an error recovery process). Here, in the present embodiment, the microcomputer 8 selects and executes an error recovery unit that reduces the frequency of occurrence of errors from a plurality of error recovery units as the error recovery unit, and determines the error occurrence condition and the error factor. An appropriate error recovery means is selected from the result (steps 1 and 2).

At this time, when the magnetic disk drive 1 has a plurality of heads, the error occurrence condition is the magnetic head 3 where the error has occurred, and the magnetic head 3 has been positioned on the magnetic disk 2 where the error has occurred. Address information. Since the address information positioned by the magnetic head 3 has a large number of data, it is possible to reduce the data amount by holding the address information as information divided in a certain block. In addition to data errors, there are two types of data playback errors: errors in which sync data for detecting the first block of data could not be detected, and errors in which sync data was incorrectly detected in a location different from the actual data. This is a condition, and is also used to determine an error factor.

The information as to whether or not the sync error has not been detected or the sync error has been detected among the sync errors is determined by the disk control circuit 9. The disk control circuit 9 performs a read control operation, determines that a sync error has occurred when the sync data is not supplied from the signal modulation / demodulation circuit 7 within a predetermined time, and detects an error of the sync error when the sync data is supplied during a time other than the predetermined time. Judge as detection. At this time, the microcomputer 8 can determine an insufficient clock pull-in synchronized with the data at the time of data reproduction as an error factor. Therefore, the microcomputer 8 selects an error recovery operation in which parameters relating to the clock pull-in are changed.

Next, as a determination of an error factor, the positioning signal from the signal modulation / demodulation circuit 7 is determined from the positioning control circuit 6 so that the positioning of the magnetic head 3 can be offset (a state where the magnetic head 3 is shifted from a predetermined position. ) Is supplied to the microcomputer 8 as to whether or not the error has occurred. Since the microcomputer 8 can determine that an offset has occurred in the magnetic head 3 by the occurrence of the offset, the microcomputer 8 performs an error recovery operation in which the positioning offset is applied to the magnetic head 3 as an error recovery means. An error recovery operation in which a positioning offset is applied to the magnetic head 3 may be selected as a normal recovery means because data may be written with a positioning offset during writing.

The read / write circuit 5 or the signal modulation / demodulation circuit 7 supplies an error signal to the microcomputer 8 by checking signal quality and waveform abnormalities. For example, by determining whether or not the signal amplitude of the output waveform is a specified value, the microcomputer 8 can determine that an abnormal amplitude has occurred or that the output waveform has asymmetry above and below. In this case, the microcomputer 8 selects an error recovery condition in which the setting parameters of the read / write circuit 5 are changed. For example, when the magnetic head 3 uses a magnetoresistive head, an error recovery condition in which the bias current is changed is selected. Further, it is possible to select a process of executing a write operation at a place other than data for recovering from an abnormal state in which the magnetic head 3 generates Barkhausen noise.

Further, in the case of a magnetic disk drive using a magnetoresistive head for the magnetic head 3, the read / write circuit 5 or the signal modulation / demodulation circuit 7 causes an abnormal increase in the amplitude value of the read signal or the output waveform. By detecting the change in the low frequency component from which the signal component has been removed, the magnetic head 3
The microcomputer 8 can determine that a phenomenon such as thermal asperity (hereinafter, referred to as thermal asperity) caused by contact with the magnetic disk 2 or a protrusion or foreign matter on the magnetic disk 2 has occurred. At this time, the microcomputer 8 raises the lower limit signal band among the signal bands of the read / write circuit 5 and the signal modulation / demodulation circuit 7 so as to compress the time affected by the thermal asperity and to prevent the gain of the signal modulation / demodulation circuit 7 from changing due to the thermal asperity. Is fixed to a constant value.

As an error recovery processing means other than the above, the microcomputer 8 changes parameters of an equalizer and parameters for signal detection as equalization conditions of a reproduced signal of the signal modulation / demodulation circuit 7 in addition to the error recovery means. You can also choose the means to lead. The error recovery means can be selected as an error recovery condition regardless of whether an error factor is estimated or cannot be estimated, and can be selected according to each condition.

As described above, after selecting a plurality of error recovery conditions, the microcomputer 8 sets first error recovery means based on the selected error recovery conditions (step S3), and performs an error recovery process (step S4). Here, since the first retry condition is determined by a method described later, it is the highest error recovery condition among the error recovery conditions. Next, it is determined whether or not the error recovery by the error recovery process has succeeded (step S5). At this time, if the error recovery unit does not succeed and an error occurs, the error recovery condition is changed and the next (or second) error recovery unit is set (step S6), and the error recovery operation is executed.

While changing the error recovery conditions in the above processing, the selected error recovery means is terminated, or
This operation is repeated as long as there is time for error recovery processing (steps S4 to S7). If the selected error recovery condition ends, or if there is no more time available for the error recovery process, the process ends as error recovery is impossible. At this time, the result of the error recovery means in which the error recovery processing has failed is updated and stored (step S8). After the execution of the error recovery process (step S4), if the error recovery process is successful, the results of the error recovery unit that succeeded in the error recovery process and the error recovery unit that failed in the error recovery are updated and saved (step S8). Thereafter, the error recovery processing ends (error recovery processing ends).

Here, as a method of updating the error recovery result, various methods for determining the priority of the error recovery means can be considered. The first method is to add the number of successful error recovery. This is because the higher the number of successful error recovery times, the higher the error recovery effect. However, in this case, since the number of times of performing the error recovery is unknown, a high recovery effect may not always be exhibited.

A second method is to save the success rate of the error recovery means as a result. This is calculated by the number of successful executions of the error recovery unit with respect to the predetermined number of executions of the error recovery unit. The higher the ratio is, the higher the error recovery effect is, and the priority of the error recovery means is determined to be higher. Here, if the parameter (number of times of error recovery means performed in the past) when calculating the error recovery rate is large, the fluctuation of the calculation result is small and the stability is high, but a large storage area is required. And when the error recovery condition that is highly effective against the error factor changes, the followability deteriorates. For this reason, it is necessary to limit the number by a certain number, and an appropriate value is selected depending on the disk device. Here, the success rate of the error recovery means is calculated for each error occurrence condition and error factor determination result.

By selecting an error recovery means from the result (step S1, step S3, step S5),
The error recovery operation is always performed from the error recovery means having a high error recovery success rate. If the error recovery processing time runs out and the error recovery processing is interrupted, the means that did not have an effect on the error recovery processing have a lower priority. When this is done, there is also an effect that error recovery means that could not be implemented before can be implemented. Thus, in the error recovery processing, the error recovery performance can be improved, and the time required for the error recovery processing can be shortened. As a result, data recovery processing when an error occurs can be performed within a limited time, and there is an effect that data throughput performance can be improved. It should be noted that the present invention is not limited to the above embodiments, and it is apparent that each embodiment can be appropriately modified within the scope of the technical idea of the present invention.

[0025]

As described above, according to the first aspect of the present invention, when performing the error recovery processing,
An appropriate error recovery means is selected from the determination result of the error occurrence factor and the condition at the time when the error occurred, the error recovery processing is performed by the selected error recovery means, and the result of the error recovery processing by the performed error recovery means is performed. Can be updated and stored by the error recovery processing result storage means. Therefore, since an appropriate error recovery means can be selected from the determination result of the error occurrence factor and the condition when the error occurs, there is an effect that the error recovery processing can be performed first from the recovery means having a high error recovery effect. . As a result, the error recovery performance is improved, and the time required for the error recovery processing can be reduced. As a result, the data recovery processing when an error occurs can be performed within a limited time, and the data throughput performance can be improved.

According to the second aspect of the present invention, in addition to the above-mentioned effects, the error recovery means is selected and executed according to the result updated by the previous error recovery processing, thereby further recovering the error. This has the effect of improving the performance and shortening the time required for error recovery processing.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an error recovery operation according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk device 4 ... Magnetic circuit 5 ... Read / write circuit 6 ... Positioning control circuit 7 ... Signal modulation / demodulation circuit 8 ... Microcomputer (a circuit which can judge the cause of error occurrence) 9 ... Disk control circuit Step S1 ... Error occurrence condition Step S2: Error recovery means selection (selection of error recovery means) Step S4: Error recovery processing execution (error recovery processing execution means) Step S8: Error recovery result Update and save (error recovery result saving means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 19/04 501 G11B 19/04 501Z

Claims (2)

[Claims] The present invention has a circuit and means capable of determining the cause of an error when an error occurs, and selecting a plurality of error recovery means from a result of the determination of the cause of the error and a condition when the error occurs. A magnetic disk drive, comprising: an error recovery processing execution unit for performing a recovery process; and an error recovery processing result storage unit for storing a result of the error recovery process. 2. The magnetic disk drive according to claim 1, wherein
A magnetic disk drive characterized in that the error recovery means can be selected according to the result of performing the past error recovery means.