JPH035977A - Magnetic disk access system - Google Patents

Abstract

PURPOSE:To enhance the accessing efficiency at the time of simultaneously accessing the information in different cylinder positions on the same medium by controlling two pieces of the head arms of a magnetic disk device in accordance with describing algorism. CONSTITUTION:This system is constituted of a central processing unit 1, an input/output processing unit 2, a magnetic disk processing unit 3 and a magnetic disk device 4. The magnetic disk device 4 is provided with the two head arms 6, 7 for accessing the magnetic head nonsynchronously with the magnetic disk 5. The accessing efficiency, such as the max. value of seek time and load dispersion, is studied and the two head arms 6, 7 of the same medium are selected at the time of executing queue registration by previously possessing the information on the cylinder positions, etc., of each of the head arms 6, 7 of the magnetic disk 5 in the central processing unit 1 and generating the request for input and output. The accessing is then executed actually by the corresponding head arm 6 or 7 with the magnetic disk device 4 via the input/output processing unit 2 and the magnetic disk processing unit 3. The information read by way of the path reverse therefrom is transmitted to the central processing unit 1. The accessing efficiency is enhanced in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk access system connectable to general-purpose computers, terminals, various computers, and the like.

[Conventional technology]

Conventionally, this type of magnetic disk device has only one Herad arm, and therefore having files that may be accessed synchronously on the same medium will reduce access efficiency, so the file layout must be determined with considerable operational consideration. There was a need.

[Problem to be solved by the invention]

The conventional magnetic disk device described above cannot access multiple cylinders on the same medium at the same time, and depending on the timing of the access request and the position of the cylinder to be accessed, the i10 execution queue length and seek distance are increased to improve access efficiency. The drawback is that it can cause problems and require considerable consideration in determining the file layout on the media.

[Means to solve the problem]

The magnetic disk access system of the present invention is characterized by having a magnetic disk device having two head arms that can operate asynchronously, and means for efficiently selecting the head arms.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are a block diagram of an embodiment of the magnetic disk access system of the present invention and an enlarged vertical sectional view of the magnetic disk device 4, respectively.

FIG. 2 is a top plan view of the magnetic disk device 4 of this embodiment.

The magnetic disk access system of this embodiment is composed of a central processing unit 1, an input/output processing unit 2, a magnetic disk processing device 3, and a magnetic disk device 4. The magnetic disk device 4 is provided with two head arms 6, 7 for asynchronously accessing the magnetic disk 5 with a magnetic head.

Next, this embodiment will be explained based on FIG.

First, information such as the cylinder position and movement direction of each helad arm 6, 7 of the magnetic disk 5 is stored in the central processing unit 1 in advance. Then, when generating an input/output request and registering it in a queue, consider the maximum seek time and access efficiency such as load distribution, and select the two helad arms 6 and 7 on the same medium. Processing device 2. !
The magnetic disk device 4 is actually accessed via the magnetic disk processing device 3 by the corresponding herad arm 6 or 7, and the read information is transmitted to the central processing unit 1 via the reverse bus.

Next, an algorithm for selecting the two head arms 6.7 will be explained based on FIG.

First, the i/ of head arm 6 and helad arm 7.

If there are differences in queue length, select the one with the shorter queue length from the perspective of load distribution. Next, if the i10 queue lengths are the same, the head arm 6.7 selects the one whose seek distance from the current cylinder position to the requested cylinder is shorter.

If they are the same, choose the one with the shorter rotation waiting time.

In the figure, the head arm 7 is positioned at position A (cylinder 200 of magnetic disk 5) and position [B (cylinder 9
00), the state of the head arm 6 is shown. At this time, if the i10 queue lengths of both are zero, head arm 6 is selected when there is an access request to cylinder 800.

Also, even if the head arm is busy (in use), if re-seeking from the position after the seek completion will result in the shortest seek distance, select that head arm and register it in the I/O queue. shall be taken as a thing.

〔Effect of the invention〕

As explained above, the present invention optimizes seek time and distributes load when simultaneously accessing information at different cylinder positions on the same medium by controlling two helad arms in a magnetic disk drive based on a descriptive algorithm. This has the effect of increasing access efficiency. Furthermore, there is an advantage that conventional methods do not require consideration of the layout of files on the same medium.

1... Central processing unit, 2... Input/output processing unit, 3... Magnetic disk processing unit, 4...
...Magnetic disk device, 5...Magnetic disk, 6,7...Head arm.

Claims (1)

[Claims] Two head arms that can operate asynchronously are provided to enable synchronous access to the same medium from two systems.
A magnetic disk access system characterized by increasing access efficiency by optimizing seek time and distributing loads when selecting the two head arms.