JPH0341603A - Magnetic disk storage device - Google Patents

Abstract

PURPOSE:To transfer data at high speed by erasing the data written on a track of a magnetic disk when the data cannot be read, and rewriting the said data transferred in the offtrack state from another storage medium by a magnetic head. CONSTITUTION:A transfer control means 6, based on the result of decision by a data reading and deciding means 4, controls to preserve the data while it can still be read by transferring the data to a storage medium 5 other than a magnetic disc 1m. When the data can no longer be read, the data is transferred from the other storage medium 5 where it is preserved to the magnetic disk 1m. The data written on the track of the magnetic disk 1m is erased by a rewriting control means 7, and the data transferred from the other storage medium 5 by the magnetic head 2m is written while still in an offtrack state. Thus, the data can be transferred at high speed.

Description

[Detailed description of the invention] (Table of contents) Overview Industrial field of application Conventional technology (Figs. 6, 7, and 8) Problems to be solved by the invention (Fig. 9) Problems to be solved by the invention Means (FIG. 1) Effect (FIG. 1) Embodiments (FIGS. 2, 3, 4, and 5) Effects of the invention (Summary) The present invention provides a plurality of magnetic disks and a magnetic disk. Regarding a magnetic disk storage device equipped with a magnetic head that moves across the track as one unit and simultaneously writes and reads data on the target track, there are other normal conditions on the surface of the magnetic disk where off-track occurs. In a magnetic disk storage device such as the one described above, the amount of displacement of the position of the magnetic head relative to the position of data written on each track on each surface of the magnetic disk is measured. If it is determined that data cannot be read on any magnetic disk surface based on the measurement results, the data written on the track of that magnetic disk is erased and the off-track state is restored. The data is written again using the same magnetic head.

(Industrial Application Field) The present invention relates to a magnetic disk storage device, and particularly relates to a plurality of magnetic disks installed on the same axis at intervals, and tracks concentrically divided on each surface of the magnetic disk. The present invention relates to a magnetic disk storage device equipped with a magnetic head that moves across as one unit and simultaneously writes and reads data to and from a target track.

(Prior Art) As a conventional magnetic disk storage device, for example, the one shown in FIG. 6 is known.

In FIG. 6, lla, llb, llc, and lid are magnetic disks as data storage media disposed at intervals on the same axis, and 12a, 12b, and 12c are common axis 14.
The magnetic disks 11a are fixed together at intervals.

11b, llc, and an access arm 13a that moves together horizontally on the track on each side of the lid and positions it on a target track, that is, performs a seek operation;
・, 13f are provided above and below the tips of the access arms 12a, 12b, and 12c, respectively, to store magnetic disks lla, llb.
, llc.

This is a magnetic head that writes and reads data on each surface of the lid. In addition, 15 is a central processing unit (hereinafter referred to as
Access arm 1
A head positioning control device 16 controls the seek operations of 2a, 12b, and 12c; similarly to the head positioning control device 15, the magnetic head 13a,
. . . is a read/write control device that controls writing and reading of 13f.

Each surface of the magnetic disks lla, llb, llc, and lid is made up of a concentrically divided track 17 and a sector 18 that is circumferentially divided into several sections, as shown in FIG. Become. The sector 18 is the minimum unit in which one piece of data is stored, and includes a data area 19 in which data is written and stored, and a side address and track address as identification information indicating the location to specify the location of this data area 19. , and an ID area 20 in which ID information such as a sector address is stored.

In a magnetic disk device with such a configuration, usually
As shown in FIG. 8, access arms 12a, 12b,
12c integrally includes magnetic disks lla, llb, llc.

Move on the track 17 on each side of the lid to select the sector I.
The ID information written in the D area is read and each magnetic head 13a, . . . , 13f is attached to the target sector.
, and the data written to that sector can be written or read at the same time.

[Problem to be solved by the invention]

By the way, in such a magnetic disk storage device, the access arms 12a, 12b, 1
2c and the common shaft 14, or the magnetic head 13a.
,..., 13f and access arms 12a, 12b.

Looseness etc. will occur at the joint part 12c. Then, the access arms 12a, 12b, 12c and the magnetic head 1
When the magnetic heads 13a, . . . , 13f perform a seek operation due to the position of the magnetic heads 13a, . There is a deviation from the position of the track 17 or sector 18, that is, off-track occurs.

Even in such a case, if the amount of displacement between the target track 17 position and the position of the magnetic heads 13a, . . . , 13f, that is, the amount of off-track, is small, the magnetic heads 13a, . 13f is the ID of sector 18
It is possible to read the ID information of the area and read the data.

However, due to long-term changes over time, as shown in FIG. 9, for example, the positions of the magnetic heads 13c and 13f become largely deviated and the amount of off-track increases.
13f makes it impossible to read and decode the ID information of the sector, resulting in a magnetic disk surface that cannot be positioned over the data area of the target sector.

In this case, the magnetic heads 13a, . . . , 13f correspond to magnetic disks lla and llb, respectively.

Since each surface of the magnetic heads 13c and 11c and the lid are moved together to position them on the same track and read data at the same time, the magnetic heads 13c and 1 have a large amount of off-track.
3d, and other magnetic heads 13a, 13b, and 13e.

13f could not be individually aligned and positioned on the same track.

For this reason, it is not possible to read data on the surface of the magnetic disk where off-track occurs and data on other normal magnetic disk surfaces at the same time, and there is a risk that it will not be possible to meet the recent demands for high-speed data transfer. was there.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic disk storage device that can read data on a magnetic disk surface where off-track occurs simultaneously with other normal magnetic disk surfaces.

(Means for solving the problems) In the present invention, the means for solving the above problems are as follows:
As shown in FIG. 1, a plurality of magnetic disks la and lb are coaxially installed at intervals.

lc,... and these magnetic disks 1a, 1b, 1c,
A magnetic head 2a moves integrally across a track divided concentrically on each side of . . . and simultaneously writes and reads data on a target track.

2b, 2cs..., on each side of the magnetic disks 1a, 1b, 1c,...
The off-track amount measuring means 3 measures the off-track amount which is the amount of displacement of the position of the magnetic heads 2a, 2b, 2c, . . . with respect to the position of data written on each track; Based on the measurement results of
Data reading determination means 4 determines whether data written on a track can be read on any surface of 1m of magnetic disk, and based on the determination result of the data reading determination means 4, the data is readable before the data can be read. The data is controlled to be transferred to and stored in a storage medium 5 other than the magnetic disk 1m, and if it is determined that the data cannot be read, the data is transferred from the other storage medium 5 to the magnetic disk In. If it is determined that the data cannot be read by the transfer control means 6 and the data reading determination means 4, the data written on the 1m track of the magnetic disk is erased, and the magnetic disk remains in the off-track state. This is because a rewrite control means 7 is provided which controls the head 2m to write the data transferred from another storage medium 5.

Note that the other storage medium 5 may be a memory other than the magnetic disk device concerned, or may be a memory other than the magnetic disk device 1a, 1b,
If there are any unused magnetic disks among 1c, . . . , that is fine.

(Function) The off-track amount measuring means 3 measures the magnetic disks 1a and 1b.
, 1c, . . . , the magnetic heads 2a, 2b correspond to the position of data written on each track.

The amount of off-track, which is the amount of displacement at the positions 2c, . . . , is measured. Then, the data reading determining means 4 determines whether or not data written on a track on any surface of the magnetic disk 1m can be read based on the measurement result by the off-track amount measuring means 3. The transfer control means 6 controls the data to be transferred to and stored in a storage medium 5 other than the magnetic disk 1m while the data can be read, based on the determination result of the data reading determination means 4, and the data is When the data cannot be read, the data is transferred from another storage medium 5 in which the data has been stored to the magnetic disk 1m. Then, the rewriting control means 7 erases the data written on the track of the magnetic disk 1m, and erases the data transferred from the other storage medium 5 by the magnetic head 2m which remains in the off-track state. Write it down. Therefore, the magnetic head 2 remains off-track on the 1 m surface of the magnetic disk.
By performing a seek operation on the data using m, the magnetic head 2m can be positioned on the track where the data has been written, and the data can be read.

(Example) Hereinafter, an example of a magnetic disk storage device according to the present invention will be described based on the drawings.

As shown in FIG. 2, the magnetic disk storage device of this embodiment includes a magnetic disk section 21 and an off-track amount measuring section 31.
and a rewrite control section 41.

The magnetic disk unit 21 includes a plurality of magnetic disks 2La and 21b as storage media arranged coaxially at appropriate intervals (four in this embodiment).

21c and 21d are provided. magnetic disk 21a,
21b.

21c and 21d are rotated coaxially by a drive device (not shown), and each surface thereof is divided into tracks and sectors as shown in FIG. 7, as in the conventional example. And each magnetic disk 21a, 21b, 21c.

21d are provided with access arms 22a, 22b, 22c that are fixed to a vertical shaft 24 and move as one. Magnetic disks 21a, 21b, 21c, Magnetic heads 23a, . . . , 23f are attached to simultaneously write and read data on each surface of the magnetic head 21d. Positioning to the magnetic heads 23a, . . . , 23f is as follows:
Head positioning control device 25 according to instructions from CPU 61, etc.
Based on the ID information of the target sector 18, access to the data area 19 of the target sector 18 is made possible. In addition, data reading and writing control is
Similar to the head positioning device 19, the read/write control device 26 performs this operation based on commands from the CPU 61, etc.

Next, the off-track amount measurement unit 31 sends the head positioning control device 25 to each of the magnetic disks 21a, 21b,
Magnetic heads 23a,..., 2 on each surface of 21c, 21d
A head offset control circuit 32 sends a control signal to offset 3f forward and backward by a predetermined amount (the maximum is the distance between adjacent tracks), and each magnetic head 23a...
, 23f is offset, the off-track amount detecting device 34 includes an error number counter 33 that counts the number of errors with respect to the track of each magnetic head 23a, . . . , 23f at four points. The number of errors is calculated by comparing the ID information written in the ID area of the sector of the target track with the ID information currently read by the magnetic heads 23a, . . . , 23f, and calculating the amount of displacement by the number of bits. It is counted. Further, the off-track amount measurement unit 31 calculates the number of errors at the four points detected by the off-track amount detection device 34 using a method described later to determine the center position of the track, and calculates the center position of the track, and calculates the number of errors at the four points detected by the off-track amount detection device 34 to determine the center position of the track.

An off-track amount calculating device 35 for calculating the off-track amount on each surface 21b, 21c, and 21d is shown on the right.

Further, the rewrite control unit 41 includes an off-track amount maximum value determination device 42, a data read determination device 43, a data transfer control device 44, and a rewrite control device 45. The off-track amount maximum value determination device 42 determines the maximum of the off-track amounts obtained by the off-track amount calculation device 35. Data reading determination device 4
3 is based on the determination result by the off-track amount maximum value determining device 42, and determines the maximum value of the off-track amount and a predetermined data reading limit value (in case 37 of this embodiment).
zm) to determine whether data with the maximum off-track amount can be read, and sends the determination result to the data transfer control device 44 and rewrite control device 45. The data transfer control device 44 is
When the data read determination device 43 sends a determination result that the off-track amount is smaller, the data and ID information indicating its storage location are sent to the magnetic disk unit 21.
However, when a judgment result is sent that the off-track amount is larger, the data transfer control device 44 causes the data to be stored in another storage medium 4so. The relevant data and its I
It controls the transfer of the D information to the magnetic disk section 21. Further, the rewrite control device 45 operates only when the data read determination device 43 determines that the off-track amount is larger than the read limit value, and at that time, the rewrite control device 45 operates The tracks or sectors on the surface of the magnetic disk where data had been written are erased, and the magnetic head, which is in an off-track state, is used to erase the ID information and the magnetic disk section 21.
It sends a command signal to rewrite the transferred data.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG.

First, magnetic disks 21a and 2 on which nothing is written
Before writing data to 1b, 21c, and 21d, write the format on each side and set it to the initial state (ST 1
). In other words, as shown in FIG.
The surfaces 1a, 21b, 21c, and 21d are divided into tracks 17 and sectors 18, and the sectors 18 are provided with an ID area 20 and a data area #219. Then, ID information indicating the storage location of the data area 19 is written in the ID area 20.

Next, on each surface of the magnetic disks 21a, 21b, 21c, and 21d, the magnetic heads 23a, . Then, the written data is read (ST2). The data area 19, which is the data storage location, has the ID of the ID area 20.
Since it corresponds to the information, the magnetic head 23a,...
Under the control of the head positioning control device 25, the head positioning control device 25 performs a seek operation based on the ID information, positions the target sector in the data area 19, and writes and reads data.

However, when a magnetic disk device is used for a long time, the positions of the magnetic heads 23a, . Off-track occurs.

Therefore, the operator uses a terminal device (not shown) to send a command to start diagnosis to the CPU 61, using the usage time of this device as a guide, and off-tracks the magnetic disk 21a.
, 21b, 21c, and 21d. Then, CPU61
A command is sent to the off-track amount detection device 34 of the magnetic disk device to start its operation.

In the off-track amount detection device 34, the head offset control circuit 32 receives the command, and the head positioning control device 2
5, a control signal is sent to the magnetic heads 23a, . . . , 23f to offset them back and forth on the track.

Then, while the magnetic heads 23a, . . . , 23f are offset back and forth on the track, the error number counter 3
3 receives the instruction and uses the method shown in Figure 5.
At each of the four points, the number of errors for the track of each magnetic head 23a, . 21d Calculate the amount of off-track on each surface (ST3).

That is, in FIG. 4, the position A is the position of the magnetic heads 23a, . . . , 23f where off-track is currently occurring.

Although the position of the magnetic heads 23a, . . . , 23f at point A is not known, the part where ID information can be read at that point is compared with the ID information stored in the ID area 20 to determine the error. Count the number EA by the number of bits.

Then, the magnetic heads 23a, .
count. As a result, if EA>E,B, then offset from point B in the same direction and calculate the error number Ec at each of the two points C, D in the same way as at point A.
Find Eo. If E A < E a , then offset from point B in the opposite direction and calculate the error numbers Ec and Eo at two points C and D, respectively, in the same manner as above. The latter case is shown in FIG.

Then, as shown in the figure, the off-track amount calculation device 35 takes the "distance" on the horizontal axis and the "r error number" on the vertical axis, and calculates the straight line connecting point A and point B to point C. Consider a straight line connecting the dots and find the intersection point R0 of the two straight lines. This intersection R8 is the center of the track where the number of errors is the minimum, and the off-track amount calculation device 35 calculates the amount of displacement between the two points from the position of the intersection R0 and the position of point A, and this becomes the off-track amount. . The above operation is performed on each magnetic disk 21a, 2.
The magnetic heads 23a, .
The amount of off-track is determined by 3f.

Each magnetic disk 21 is
After detecting the off-track amount for each track on each surface of surfaces a, 21b, 21c, and 21d, the off-track amount maximum value determining device 42 detects the maximum value of the off-track amount and its data ( Sr1).

Then, the data reading determination device 43 compares the maximum value of the off-track amount with a preset reading limit value (approximately 3 JLm) at which data cannot be read due to off-track, and determines which value is larger. The data transfer control device 44. and sends the determination result to the rewriting control device 45 (Sr1).

When the data transfer control device 44 receives a determination result that the maximum value of the off-track amount is smaller than the reading limit value and that the data can still be read, the data transfer control device 44 sends a control signal to the CPU 61 based on the determination, and sends a control signal to the CPU 61 based on the determination. It reads data and ID information indicating the area where it was written, and transfers both from the magnetic disk surface to another storage medium.
Control is performed so that the data is transferred to 0 and stored (Sr1).

On the other hand, when the data transfer control device 44 receives a determination result that the maximum value of the off-track amount is larger than the reading limit value and that the data cannot be read, the data transfer control device 44 has already deleted the data and the ID information corresponding to it. Since it should have been saved in another storage medium 60 due to the previous diagnosis, a control signal is sent to the CPU 61 and the data is saved in the other storage medium 60.
The data is controlled to be transferred from the magnetic disk unit 21 to the magnetic disk unit 21 (Sr7).

On the other hand, the rewrite control device 45 sends a data rewrite control signal to the read/write control device 26 only when the determination result that the maximum value of the off-track amount is larger than the read limit value is sent.

Then, under the control of the rewrite control device 26, the read/write control device 26 first offsets the magnetic head to erase the data area and ID area of the track or sector where the data was stored, and writes nothing. (Sr1).

Next, the read/write control device 26 writes the ID information of the data transferred from another storage medium 60 using the magnetic head that remains in the off-track state in the vicinity of the erased track or sector, and writes the ID information of the data transferred from the other storage medium 60 to the ID area. The data area 19 located according to the ID information is activated, and only the erased track or sector part is reformatted (Sr9).

Then, under the control of the rewrite control device 44, the read/write control device 26, for example, as shown in FIG.
Magnetic heads 26c and 26d still in off-track state
However, the position is slightly shifted from the track where the relevant data was previously (the part surrounded by the chain line) (the part with a grid pattern)
Then, the data transferred from the other storage medium 60 to the magnetic disk storage 21 is written again into the data area located by the ID information (ST 10).

Then, the magnetic disks 21a, 21b, 21c, 21d
Even if off-track occurs on any surface of the magnetic head due to aging and data cannot be read simultaneously on other surfaces, as shown in FIG.
Since new data is written with the magnetic head 6d in an off-track state, the magnetic heads 23a, . . . , 23f are rewritten.
can read data simultaneously on each side of the magnetic disks 21a, 21b, 21c, and 21d (ST2).

Therefore, according to this embodiment, the data having the largest amount of off-track, that is, the data closest to the state where the data becomes unreadable due to off-track, is preferentially transferred in advance to another storage medium 60 and stored there. Depending on the change, magnetic disks lla, llb, llc, ll
When off-track occurs on the surface d and data cannot be read, the magnetic disks 21a, 21b, 21c
, 21d, the sector in which data was written on that side is erased and reformatted, the data is transferred from another storage medium 60, and the data is written using the magnetic head in that state. Even if an off-track occurs due to long-term use, the data stored on the track where the off-track has occurred can be read simultaneously with data on other normal surfaces, and multiple data can be written and read simultaneously. This makes it possible to meet recent demands for high-speed data transfer.

In this embodiment, only the maximum amount of off-track is compared with a read limit value set in advance by the data reading determination device, and whether the data is transferred from the magnetic disk device to another storage medium or The data is transferred from another storage medium to the relevant magnetic disk device and rewritten, but a certain range of data whose off-track amount is less than the read limit value is transferred to the other storage medium in advance. , the data in that range may be compared with a reading limit value to determine whether or not to perform rewriting.

Further, in this embodiment, the other storage medium 60 may be a memory 21 other than the magnetic disk device, and among the magnetic disks 21a, 21b, 21c, and 21d,
If you have an unused magnetic disk, you may use it.

Furthermore, although the time interval for measuring the amount of off-track is not specifically set in this embodiment, how many hours does it take to use the magnetic disk device before off-track occurs, and how long does it take to read the data? It is possible to collect data on whether or not it has disappeared, set an appropriate time interval or cycle, and have the operator perform the inspection at each time, or it may be possible to automatically perform the measurement using a program, etc. . Further, in this embodiment, the number of errors when reading ID information is used to measure the off-track amount, but the off-track amount is not limited to this method.

〔Effect of the invention〕

As explained above, according to the magnetic disk device according to the present invention, the data having the largest amount of off-track, that is, the data closest to the state where the data becomes unreadable due to off-track, is preferentially transferred to another storage medium in advance. Therefore, if off-track occurs on a certain magnetic disk surface due to changes over time and the data becomes unreadable, you can erase the sector in which data was written on that side of the magnetic disk and try again. The data is formatted and transferred from another storage medium, and the data is written using the magnetic head in that state, so even if off-track occurs due to long-term use, it will not occur. The data stored on the track can be read at the same time as data on other normal surfaces, and multiple data can be written and read simultaneously, meeting the recent demands for high-speed data transfer. This greatly contributes to improving the performance of disk devices.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a diagram showing an embodiment of a magnetic disk device according to the present invention, FIG. 3 is a diagram showing the operation of this embodiment, and FIG. 4 is a diagram showing off-track amount calculation. FIG. 5 is a diagram showing the features of the operation of this embodiment, and FIG.
The figure shows a magnetic disk device according to a conventional example, Fig. 7 shows tracks and sectors of a magnetic disk, Fig. 8 shows the operation of the conventional example, and Fig. 9 shows off-track and data cannot be read. FIG. 1a, 1b, 1c, ... magnetic disks 2a, 2b,
2c,...Magnetic head 1m...(Off-track has occurred) Magnetic disk 2m...(Off-track has occurred) Magnetic head 3...Off-track amount measuring means 4...・Data reading determination means 5...Other storage media ・Transfer control means ・Rewriting control means 2nd request? 11 Flow - + Ya -9I3
Figure 4 Figure 4 Figure 4 Figure 4! ? Ittsu l-u-fu ga coughing data gullet Xg lena...
Medium (Kan 1 Hemaro Figure 9)

Claims (1)

[Claims] A plurality of magnetic disks (
1a, 1b, 1c,...) and this magnetic disk (1a, 1c,...).
A magnetic head (1b, 1c, . . .) moves across concentrically divided tracks on each surface of the magnetic heads (2
a, 2b, 2c, ...), the magnetic head (2a, 2c, ...) corresponds to the position of data written on each track on each surface of the magnetic disk (1a, 1b, 1c, ...). 2b, 2c,...), and an off-track amount measuring means (3) for measuring the off-track amount, which is the amount of displacement at the positions of the magnetic disks (2b, 2c,...). 1 m) for determining whether data written on the track can be read or not;
), the data is controlled to be transferred to and stored in a storage medium (5) other than the magnetic disk (1m) while the data is readable, while the data is determined to be unreadable. transfer control means (6) that controls the data to be transferred from another storage medium (5) to the magnetic disk (1 m) when the data is determined to be unreadable by the data read determination means (4) , the data written on the track of the magnetic disk (1 m) is erased, and the magnetic head (2 m), which remains off-track, is used to transfer the data to another storage medium (5).
1. A magnetic disk storage device comprising: rewrite control means (7) for controlling the rewriting of the data transferred from the magnetic disk storage device.