JP2003141703A - Magnetic disk unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a function for suppressing a write defect under a low- temperature environment. SOLUTION: After writing write data into a magnetic disk 3, an ambient temperature is measured by a temperature sensor 151, and compared with a temperature range value 52 enabling a normal operation. When it is out of range, write data 41 are compared with read data 42, and dummy write is carried out in order to raise head temperature in the case of noncoincidence. This operation is repeated until the write is completed normally or predetermined time passes.

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 for storing information in a computer system including a personal computer and a workstation, and more particularly,
The present invention relates to a magnetic disk device having an improved write failure suppression function under a low temperature environment.

[0002]

2. Description of the Related Art In recent years, information storage devices such as magnetic disk devices have been becoming higher in density and speed. With the increase in density and speed, the environmental temperature at the time of operating a magnetic disk device has become more and more important as a condition for recording information on a recording medium.

For example, the magnetic characteristic of a magnetic disk changes with temperature. When the temperature rises, the coercive force becomes smaller and the disk can be magnetized sufficiently with a small write current. Further, as the temperature decreases, the holding power increases, so that a large write current is required. On the other hand, when the coercive force becomes small, the magnetization is magnetized with a small write current.
If an excessively large write current is supplied, the magnetization is propagated to the surroundings and the writing spreads, resulting in data damage. Further, when the coercive force becomes large, a large write current is required for magnetization, so that it is not possible to sufficiently magnetize with a small write current, and it becomes impossible to stably record information.

Therefore, for example, Japanese Patent Laid-Open No. 10-340
As disclosed in Japanese Patent Application Laid-Open No. 412, Japanese Patent Application Laid-Open No. 11-45406, Japanese Patent Application Laid-Open No. 2000-222703, etc., a method of writing by selecting an optimum write current according to temperature has been proposed.

[0005]

However, the densification is
At present, the head itself is compatible with high density recording / reproducing separated thin-film magnetic heads having an inductive recording head integrally formed on the magnetoresistive reproducing head through a magnetic shield. Has been devised,
It can be said that the influence of the environmental temperature is not limited to the relationship between the coercive force and the write current value, and that the distortion of the fine structure of the magnetic head due to the low temperature of the environment may cause the write failure.

[0006] Only by the method of controlling the write current value by the temperature change as disclosed in the above-mentioned publication,
It is impossible to solve the problem of defective writing, which is considered to be caused by the distortion of the fine structure of the magnetic head.

[0007]

In order to achieve the above object, the present invention relates to a magnetic disk for recording data transferred from a host computer, or a magnetic head for writing and reading data to and from the magnetic disk. The temperature of the magnetic disk device is measured.If this temperature exceeds the temperature range where the magnetic disk device can operate normally on the low temperature side, the recorded data is read and the written data is checked to verify that the writing was successful. Verify whether it has been done. If it is determined that the collated data do not match and writing was not performed normally, move the magnetic head to the dummy data area of the magnetic disk, apply a head heating current to the magnetic head, and then perform the predetermined recording. Return to the position and try writing again.

It is known from the inventor's knowledge of writing defects at low temperatures that writing defects may be resolved while writing is continued for several sectors even if there are writing defects. based on. That is, there is a possibility that the writing failure due to the low temperature of the environment may be caused by the distortion of the fine structure of the magnetic head, which means that while the write current is being applied to the magnetic head, That is, it is considered that the magnetic head is improved to the extent that the distortion is eliminated.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to FIGS. 1 to 6 showing an embodiment of the present invention.

FIG. 1 shows a configuration example of a personal computer using the magnetic disk device 1. This personal computer has a host computer 2 forming a part thereof and a magnetic disk device 1 as an external storage device. This basic configuration may be a so-called host computer 2 as a host device of a large-scale computer system and a magnetic disk device 1 as an external storage device. The central processing unit CPU of the host computer 2 is the bus line 2
A command is issued to the magnetic disk device 1 via 1 to exchange data.

FIG. 2 is a block diagram showing a concrete example of the configuration of a magnetic disk device according to an embodiment of the present invention.
In the configuration of FIG. 2, it is assumed that the disk medium 3 is a single magnetic disk device. A magnetic disk device in which a plurality of disk media are stacked may be used.

A large number of concentric tracks are formed on both recording surfaces of the disk medium 3, and servo areas in which servo data used for seek / positioning of the head are recorded are arranged at equal intervals on each track. ing. A data area is provided between the servo areas, and a plurality of (generally 2 to 5) sectors (data sectors) as recording units are arranged in the user area. On the disk medium 3, the servo areas are arranged radially at equal intervals across the tracks from the center. (See FIG. 3) The disk medium 3 has a user area 31 for storing data transferred from the host 2 in the data area portion and a write operation for heating the head 11 in a low temperature environment which is a feature of the invention. It has a dummy write area 32 for performing. If there is an existing dummy write area, the dummy write area 32 may be used, and it is not necessary to additionally provide it. Further, in FIG. 3, the user area 31 and the dummy light area 32 are respectively installed on separate and separate tracks, but the same track may be divided into two areas, or the user area 31. Alternatively, the dummy light areas 32 may be alternately installed on the same track.

On each recording surface side of the disk medium 3, a head (magnetic head) 11 used for writing data to the corresponding recording surface of the disk medium 3 and reading data from the recording surface is arranged. Each head 11
Is attached to a rotary type head actuator 12 as a head moving mechanism, and moves in the radial direction of the disk medium 3 in accordance with the rotation (angle rotation) of the head actuator 12. As a result, the head 11 is seek-positioned on the target track.
The head actuator 12 is a voice coil motor (hereinafter, referred to as a VC) that is a drive source of the head actuator 12.
MCM) 13 and is driven by the VCM 13. A motor driver 14 is connected to control the VCM 13, and a value (control amount) for determining the control current supplied to the VCM 13 is determined and given by the CPU 15.

Each head 11 is connected to an R / W (read / write) circuit 16. The R / W circuit 16 amplifies a read signal read from the disk medium 3 by the head 11 and amplified by a preamplifier (not shown) to a constant voltage by an AGC (automatic gain control) amplifier (not shown). For example, the AGC function, a decoding function (read channel) that performs signal processing necessary for decoding the read signal amplified by the AGC function into NRZ code data, and a data writing function that is necessary for writing data to the disk medium 3. It has an encoding function (light channel) for performing signal processing.

The buffer memory 4 is read from the write data holding area 41 and the disk medium 3 used for temporarily storing the data (write data) transferred from the host (host system) to be written in the disk medium 3. The read data holding area 42 is used for temporarily storing data (read data) transferred to the host. The buffer memory 4 is composed of, for example, a RAM (Random Access Memory) as a rewritable memory. The hard disk controller 17 controls commands (write command, read command, etc.) with the host 2, data communication, buffer control, data transfer control with the disk medium 3, and the like.

The CPU 15 is, for example, a flash ROM (Read Only Memo) as a rewritable nonvolatile memory.
ry) (hereinafter, referred to as FROM) 5 controls a magnetic disk device 1 as a whole according to a control program 51 stored therein. The CPU 15 includes a FROM and the CPU 1
A RAM 18 for providing a work area 5 and the like is connected. The FROM 5 and the RAM 18 may be built in the CPU 15. The FROM 5 is a program storage area 5 in which the control program is recorded.
1 and the temperature range value storage area 52 in which the temperature range value 52 in which the magnetic disk device 1 can operate normally is recorded. (See FIG. 5) Further, the CPU 15 has a timer 150 for measuring the time so that the processing of the command received from the host does not exceed a certain time.

Further, the CPU 15 is provided with a temperature sensor 151 for measuring the environmental temperature of the device. The temperature sensor 28 is an environmental temperature that affects the characteristics of the shape change of the head 11, that is, the disk medium 3 and the head 11.
It is preferable to arrange the head disk assembly (HDA) inside the HDA so that the environmental temperature near the head disk assembly (HDA) can be measured with high accuracy. On the other hand, in the sense that the temperature range in which the magnetic disk device can normally operate is monitored, the magnetic disk device does not necessarily have to be in the HDA, and may be installed on a printed board on which each component of the magnetic disk device is mounted. C
The PU 15 can read the detection output value of the temperature sensor 151 via an A / D converter (A / D) 152.

Next, the operation of this embodiment will be described in order with reference to FIG.

The head heating processing routine for suppressing write failure according to the present invention starts with receiving a write command from the host 2.

When the write command is received from the host 2, the timer 150 is started (step 601).

The data transferred from the host 2 passes through the hard disk controller 17, the buffer memory 4 (write data holding area 41), the R / W circuit 16 and the head 11.
And recorded as a magnetic transition on the magnetic disk 3. A series of these flows is a write operation of a general magnetic disk device (step 602). Here, the data transferred from the host 2 and stored in the buffer memory 4 is used because it will be used in a step described later, so that it is retained.

Here, using the temperature sensor 151, the HDA
Measure the ambient temperature of. As described above, the measurement result by the temperature sensor 151 is the A / D converter (A / D) 1
It is transmitted to the CPU 15 via 52. The temperature measurement may be a value at the moment when the write operation is performed in step 602, or may be an average value or a minimum value obtained by measuring a plurality of times before and after the write operation (step 60).
3).

The CPU 15 compares the temperature measurement result obtained in step 603 with the temperature range value 52 in the FROM 5 where normal operation is possible, and makes a determination (step 604). If it is within the normal operation temperature range (OK), the write operation is normally completed. If the temperature is out of the range (NG), the process proceeds to step 605. Even if it is determined in this judgment that the write operation has ended normally, if the write operation did not end normally due to other factors such as off-track writing, a prescribed recovery operation should be performed according to each abnormality. Not to mention. In Step 605, Step 6
Read the data written on the magnetic disk in 02,
The data is stored in the read data holding area 42 of the buffer memory 4. That is, when it is determined in step 604 that the temperature is abnormal, the data written on the magnetic disk is read to determine whether or not the previous write operation is normally performed, and the original data of the write in the write data holding area 41 is read. And the data in the read data holding area 42 read after writing are compared to make a determination (step 6).
06). If both data match, the write operation is completed normally. If they do not match, the process proceeds to step 607.

If it is determined in step 606 that the writing is defective, it is highly likely that the cause is the environmental temperature of the magnetic disk device. Therefore, the head 11
A write current is passed for a certain period of time to raise the temperature of the.
At this time, if a write current is passed through the user area 31, user data will be destroyed, so a write current is passed over the dummy write area 32 that is provided exclusively. When the dummy write area 32 is on a different track from the user area 31, it is necessary to control the VCM 13 to move the head 11 onto the predetermined dummy write area 32 (step 607).

After the dummy write processing in step 607 is completed, the time from the receipt of the command to the present is determined by the elapsed time of the timer 150. This is a function for preventing the write failure suppression routine from falling into an infinite loop (step 608). As a result of the determination, if it is within the predetermined time, the process returns to step 602 to perform the write operation again, and if it exceeds the predetermined time, it is determined that the writing is impossible and the writing ends abnormally.

As described above, the write failure suppression routine is continued until the write is normally completed or the write is abnormally ended after a predetermined time has elapsed.

Here, in the practice of the present invention, the write current is changed to the step 603 as in the above-mentioned known example.
As a matter of course, the temperature measurement may be performed by using the temperature measurement result before writing and by setting the optimum current according to the temperature. Further, the write current for heating the head in step 607 may be a write current according to the temperature, or may be the maximum current allowed for the head. Estimating the time required to complete one cycle through the flow steps 602 to 608 shown in FIG. 6 requires about 100 msec. However, if the write current for heating the head is the maximum current allowed by the head, this can be somewhat reduced. . further,
If the dummy write areas 32 are appropriately dispersed and arranged in the user data storage area, the time (step 607) for supplying the write current for heating the head can be reduced, and the effect of the heating processing can be exhibited. You can try writing again in time.

[0028]

As described above in detail, according to the present invention, the writing operation can be normally performed by heating the head itself even in a low temperature environment where the normal writing operation cannot be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing the configurations of a magnetic disk device and a personal computer.

FIG. 2 is a diagram showing a configuration example of a magnetic disk device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration example of a magnetic disk (medium).

FIG. 4 is a diagram showing a configuration example of a buffer memory.

FIG. 5 is a diagram showing a configuration example of a flash ROM.

FIG. 6 is a diagram showing an example of a flowchart of a head heating process for suppressing writing failure.

[Explanation of symbols]

1: magnetic disk device, 2: central processing unit (host),
3: disk medium, 4: buffer memory, 5: flash ROM, 11: head, 12: actuator, 1
3: VCM, 14: motor driver, 15: CPU, 1
6: R / W circuit, 17: Hard disk controller,
18: RAM, 31: user data storage area, 32: dummy write area, 41: write data holding area, 42:
Read data holding area, 51: program storage area, 5
2: Temperature range value in which normal operation is possible.

Claims (5)

[Claims] 1. A disk medium for storing data or for reading the stored data, a head for accessing the recording of the disk medium for storing the data or reading the stored data, controlling and storing the position of the head, or A magnetic disk device comprising a processing device for managing read data, wherein the magnetic disk device performs write processing by the head when data to be written to the disk medium is given, and operation of the magnetic disk device. A magnetic disk device characterized in that the temperature related to the environment is checked, and if the temperature is outside a predetermined area, the write data by the write processing is read and compared with the original data to judge the suitability of the write. . 2. The magnetic disk drive according to claim 1, wherein when the result of the determination as to whether or not the writing is appropriate is negative, a process of supplying a write current for heating the head to the head for a predetermined time is performed. 3. The magnetic recording medium according to claim 2, wherein the disk medium has a user area for storing data and a dummy write area unrelated to the original data, and the head is moved to the dummy write area. Disk device. 4. The magnetic disk according to claim 2, wherein the judgment as to whether or not the writing is appropriate and the processing for supplying a writing current for heating the head based on the judgment are limited within a fixed time from the receipt of the writing processing command. apparatus. 5. A print in which a temperature sensor for detecting a temperature related to an operating environment of the magnetic disk device is mounted near a head disk assembly having a disk medium and a head or a component for controlling the magnetic disk device. The magnetic disk device according to claim 1, wherein the magnetic disk device is installed on a plate.