JPH0312067A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To shorten the access time and to promote the throughput of the access by providing the magnetic disk device with plural seek mechanisms and providing a recording and reproducing circuit, a modulation/demodulation circuit and a control circuit to each seek mechanism. CONSTITUTION:Data is read and written on a recording magnetic layer on the surface of a disk medium 1 by magnetic heads 3-1, 3-2 and 3-3. These magnetic heads are fitted with the seek mechanisms 5-1, 5-2 and 5-3, each being capable of accessing a prescribed cylinder by moving a needle of the seek mechanism. Then, access can simultaneously be performed up to three places, thus shortening the waiting time for revolving the medium 1. In addition, if the individual seek mechanisms are disposed in advance on an outer circumference, in the middle and on an inner circumference of the medium 1, the seek time can also be shortened. By this method, the access time is shortened, and the throughput is promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic disk devices such as hard disks and flexible disks, and particularly to large magnetic disk devices used for frequently accessed applications such as databases.

[Prior Art] In a conventional magnetic disk drive, each spindle has one mechanism for holding and seeking a magnetic head, as shown in FIG. In FIG. 6, 1 is a disk medium;
2 is a spindle motor that drives a disk medium, 3 is a magnetic head, 4 is a gimbal that supports the magnetic head, and 5 is a seek mechanism. In such a magnetic disk device, after receiving an access request as shown in FIG. 7, the head first moves (seek) to the target cylinder, then waits until the target sector reaches the head, and then Perform recording and playback. In this case, the waiting time until the sector to be recorded or reproduced comes under the head is determined by the rotation period of the disk, and the rotation period is the maximum value. Therefore, in order to shorten this rotation waiting time, the rotation speed of the disk must be increased. Furthermore, since there is only one set of seek mechanisms, even when many disk accesses are concentrated on the same disk, reading and writing must be performed one by one in order.

Even with such a magnetic disk device, since the capacity of the magnetic disk device is small, there were not many problems while it was being used as a computer program file.

[Problem to be solved by the invention] However, in recent years, the capacity of magnetic disks has increased, and magnetic disks have come to be used as various databases, and accesses are often concentrated on one magnetic disk device. It has become. In that case,
Tasks attempting to access the same magnetic disk device must be kept waiting, which increases the user's waiting time in online transaction processing.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such conventional drawbacks and provide a magnetic disk device with short access time and high access throughput.

[Means for Solving the Problems] A magnetic disk device of the present invention includes a plurality of magnetic disk devices and a plurality of seek mechanisms for seeking each magnetic disk device, and each seek mechanism is equipped with a recording/reproducing circuit and a modulation/demodulation circuit. , a control circuit is provided.

The magnetic disk device of the present invention also estimates the time required to seek to the cylinder to which the access was requested and the time to reach the sector to which the access was requested after the seek, and selects a seek mechanism that minimizes the sum of the times. The apparatus is characterized by comprising means for selecting the mounted head.

Furthermore, when performing a write operation, the magnetic disk device of the present invention registers the cylinder, head, and sector to be written, and when performing a read, it checks this and performs other seek operations until the write operation is completed. It is characterized by comprising means for prohibiting the same sector from being read by a mechanical head.

[Effect]

In the present invention, the access time is shortened by selecting the seek mechanism that reaches the desired sector most quickly from among the plurality of seek mechanisms provided. In addition, multiple seek mechanisms and read/write circuits enable parallel reading and writing of different sectors on the disk, increasing the throughput of disk access. However, if you do this, if you continue to write or read the same sector, there is a possibility that it will be read before it is written, but the target sector will be read-protected during the write operation. This is how it is avoided.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a magnetic disk device in which there are three sets of seek mechanisms. This magnetic disk device has first, second, and third seek mechanisms 5-1.5-2.5 each having magnetic heads 3-1.3-23-3 attached thereto and linearly moving them in the directions shown by the arrows. -3 are provided at equal angular intervals, and each seek mechanism is provided with a recording/reproducing circuit, a modulation/demodulation circuit, and a seek drive circuit.

In such a magnetic disk device, a magnetic head 3-1゜3-2.3-3 is attached to the recording magnetic layer on the surface of the disk medium l.
Data is read and written by.

These magnetic heads have a seek mechanism 5-1.5-2゜5-3
A specific cylinder can be accessed by moving the mover of the seek mechanism.

In this example, up to three locations can be accessed at the same time, and if only one location is accessed, the rotation waiting time of the disk medium 1 can be shortened. By arranging them on the inner circumference in advance, the seek time can be shortened.

Here, a seek mechanism in which the mover moves linearly is used, but a rotation mechanism may also be used.

FIG. 2 shows an example of the configuration of a control device that controls three sets of first, second, and third seek mechanisms.

This seek mechanism control device controls each magnetic head 3-1゜3-
2. Register I to register the current cylinder number of 3-3
f-1, 11-2, 11-3, and a register 12-1.12-2.12-3 for registering the movement destination cylinder number. Then, calculate the difference between the current cylinder number and the destination cylinder number to estimate the seek time. In addition, the current first seek mechanism 5-1
It has a register 15 for registering a certain sector number and a register 16 for registering a sector number for which an access request has been made, and a calculator 17 calculates a sector difference (angular difference). From the obtained seek time and angle difference, the access time is determined using the access time conversion table 14-1.14-2.14-3.

The seek times for the second and third seek mechanisms 5-2 and 5-3 are similarly calculated. The angle difference is originally 2
For the 3rd and 3rd seek mechanisms, 1/3 and 2/3 of the total number of sectors should be added to the angle difference of the 1st seek mechanism, but for simplicity, these functions are included in the conversion table. I did it like that.

The access time of each seek mechanism obtained in this way is compared by a comparator I8, and the head on the seek mechanism with the shortest access time is selected. In this way, good access performance can be obtained.

Furthermore, in the magnetic disk device of the present invention, when reading, this is checked so that until the write operation is completed by the head on one seek mechanism, the same sector is read by the head on another seek mechanism. It is necessary to prohibit

The reason why such control is necessary will be explained below.

If a magnetic disk device can simultaneously read and write data on a disk medium using multiple seek mechanisms, as shown in FIG.
Immediately after a long continuous rewrite such as rewriting 27 sectors (step St), #N1 cylinder,
#N! When reading sectors #96 to #111 of the head (step 32), when reading the rear part of the rewrite area, when rewriting is being performed with the head on one seek mechanism, There is a possibility that the mechanical head will read that part before the previous rewrite is performed.

FIG. 4 is a diagram showing this situation, in which one magnetic head 21
#0 sector of #N head of #N cylinder (start writing)
- Rewrite the number of cycles from then # on the same track.
There is a request to read sectors 96 (start of reading) to #111, and the head 22 on another seek mechanism can read them. However, as shown in the figure, the part where reading is being performed has not been rewritten yet, and when the algorithm of FIG. 3 is executed, the order of writing and reading is reversed. Therefore, when performing a write operation, the cylinder that writes.

It is necessary to register tracks and sectors, check them when reading, and prohibit reading of the same sector by heads on other seek mechanisms until the write operation is completed.

FIG. 5 shows an example of the configuration of a read/write operation control device for realizing this.

At the time of fortune-telling, the cylinder, truck,
Register the sector in the write sector registration register 3I. When reading, read security register 3
Cylinder to read to 2.

A track and a sector are input, and the comparator 33 compares the contents of the read sector check register 32 and the contents of the write sector registration register 31. If there is a sector that matches, a read prohibition signal is outputted via the OR circuit 34. The read is prohibited and the write is made to wait until the write is completed.

The above is an example in which the read-inhibiting function is implemented in hardware, but of course the same function may be implemented in firmware if there is sufficient execution speed. In addition, this function can be used with disk controllers or peripheral device controllers (
Peripheral Control Unit;
It is also possible to implement it on PC'U).

A comparative study of the magnetic disk device of the embodiment described above and a conventional magnetic disk device with one seek mechanism revealed that the average access time was shortened to 1/2.2, and the access throughput was increased by 2.7 times. It increased.

In this embodiment, three sets of seek mechanisms are provided, but even in 2&H, two sets of seek mechanisms are provided.
It is expected that the performance will be slightly more than twice as high. Also, 4 groups.

By increasing the number to 5IJ1, it becomes possible to realize a disk device with even higher performance.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a magnetic disk device with short rotational waiting time and high disk access throughput.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a control device for a seek mechanism, FIG. 3 is a diagram for explaining an example of an algorithm for reading and writing operations, and FIG. 5 is a diagram illustrating the configuration of a control device for read/write operations on a magnetic disk. FIG. 6 is a diagram illustrating the configuration of a conventional magnetic disk device. The figure is a diagram for explaining the access time of a magnetic disk. 1...Disk medium 2...Spindle motor 3...Magnetic head 4...Gimbal 5...Seek mechanism 11...Current cylinder number Register 12 to register...Register 13 to register the destination cylinder number...Arithmetic unit 14...Access time conversion table 15...
-Register 16 for registering the current sector number...Register 17 for registering the sector for which access was requested...Arithmetic unit 18...Comparator 21...Writing is performed Head 22...
... Head 31 that is reading... Write sector registration register 32 ... Read sector check register 33 ... Comparator 34 ... OR circuit diagram

Claims (2)

[Claims] (1) A magnetic disk device comprising a plurality of magnetic disk devices and a plurality of seek mechanisms for seeking each magnetic disk device, and each seek mechanism is provided with a recording/reproducing circuit, a modulation/demodulation circuit, and a control circuit. . (2) Estimate the time it takes to seek to the cylinder for which access was requested and the time to reach the sector for which access was requested after seeking, and select the head mounted on the seek mechanism that minimizes the sum. The magnetic disk device according to claim 1, further comprising means. (3) When performing a write operation, register the cylinder, head, and sector to be written, and when performing a read, check this and use the same sector by the head on another seek mechanism until the write operation is completed. 3. The magnetic disk device according to claim 2, further comprising means for prohibiting the data from being read.