JPS63247987A - Seek control method for storing device - Google Patents

Abstract

PURPOSE:To shorten the total moving distance of a head and shorten the time required for executing a process, by rearranging plural commands in an input command queue and performing seeking operations. CONSTITUTION:An input-output requesting command from a host computer 14 is once put in the command queue 16 of a disk controller 15 and the command is executed against a storing device 13 which performs seeking operations. When the inputted command queue is inputted to a selecting process, the commands queue of the maximum and minimum head positions in the inputted command queue are selected. Then the distance between the current head position and the head position of the selected command queue is calculated and it is informed to the next sorting process that one of the head positions of the two selected command queue is closer to the current head position. When the queue at the maximum head position is closer, all queue are sorted in the descending order of the head positions. When the queue at the minimum head position is closer, all queue are sorted in the ascending order of the head positions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a storage device that involves a seek operation, and particularly to a control method for efficiently operating a head.

[Summary of the invention]

The present invention provides for controlling a storage device that involves a seek operation.
DISKfftl+Manual command queue (5th
16) in the figure, when executing each command, the command queue is set so that the seek operation of the head is optimized from the position of the head before execution and the cylinder where the head must be located when executing each command. By rearranging the commands in the command queue, the total head movement distance is reduced, and each command in the command queue is prioritized to ensure that no commands are left unprocessed. This allows the head to operate optimally.

[Traditional technique (nei)]

Conventionally, in a method for controlling a seek operation of a storage device, commands requesting a seek operation are randomly input and the commands are processed (seek operation) according to the input order.

[Problem that the invention seeks to solve]

However, in conventional seek operation control methods, when there are multiple commands and the cylinders in which the head must be positioned when executing each command are located randomly and separately on the disk surface, the input Process in the order (
To perform a seek operation), as shown in FIG. 1, between the current head position 11 (80) and the cylinder position ■ of the next command to be processed, the cylinder position ■ of another command is set.
When ■ exists, the head performs the seek operation once to ■ (5), then jumps over ■ (20) and ■ (50), and then
(100) Perform the seek motion and return again ■
(20) Perform a seek motion, then (240) Perform a seek motion, then return to (50), and so on.
The total head movement distance for the seek operation from to ■ is (77+95+80+220+190)=660 (
cylinder] (however, the number in parentheses indicates the amount of cylinder movement, that is, the amount of movement of the head). In this way, the head was making unnecessary movements.

[Means for solving problems]

In view of the above points, the present invention rearranges the command processing order (seek operation) by taking into account the current head position before processing input commands (seek operation), and , provides a method for optimizing command processing (seek operation) by executing a control program using priorities so that no unprocessed commands are left.

[Effect]

When the method of the present invention is used, a seek operation is performed by rearranging a plurality of commands in the input command queue, so the order of the head seek operations in FIG. 1 is as follows. The head first performs a seek operation in the requested order ■, and then performs seek operations in the order ■−■−■−■. At this time, the total travel distance for the head to perform seek operations to process commands from ■ to ■ is 310 (cylinders).
That would be enough.

〔Example〕

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram of a typical storage device with a seek operation, for explaining one embodiment of the present invention. The input/output request command coming from the host computer 4 shown in the figure is once entered into the command queue 16 of the disk control device, and the command is executed on the storage device 13 that performs the seek operation.

FIG. 1 is a longitudinal sectional view of the disk showing the head actually performing the seek operation and the seek position required by the input command. The numbers circled in the figure are examples of the order of the input command queue, and the arrows indicate the positions to which the head should move.

Also, the input command queue is shown in Figure 3.
Five input command queues are lined up in order from the left. In the figure, the numbers surrounded by O indicate the order of the input command queue, and the numbers enclosed in parentheses indicate the position to which the head should move when executing the command.

Now, when this input command queue is input to the selection process shown in the flowchart of the optimization process in Figure 2, the command queue for the maximum head position and the command queue for the minimum head position in the manual command queue are selected by the selection process. selected. Next, in the distance calculation process, the distance # (absolute value of difference) between the current head position and the head position of each selected command cue is calculated, and which of the two selected command cue head positions is the current one. The proximity to the head position is transmitted to the next sorting process.

In the sorting process, depending on the result of the distance calculation process, all input commands are sorted in descending order of head position if the command queue of the maximum head position is close, and in ascending order of head position if the command queue of the minimum head position is close. Sort queues. The results are then output as an output command queue. In this example, the current head position is set to 80, and the selection process, distance calculation process, and sorting process shown in Figure A2 are performed, and the resulting output command queue is shown in Figure 4 (A). It was shown to.

As a result, when executed according to the output command queue of FIG. 3, the total distance the head moves during execution of all commands is 310 cylinders. This is approximately half the value of 660 cylinders in the [prior art] example.

Next, in the embodiment of the selection process, distance calculation process, and sorting process shown below, a process is provided for prioritizing each command to eliminate unprocessed commands. There is a command called cylinder position ff (240) shown in Figure 3, and the cylinder position of the newly input command is from (0) to (100).
When the commands are concentrated in a distant location, the distance calculation process and the sorting process ensure that the command with the cylinder position closest to the current head is always at the head of the command queue, processed first, and the cylinder position iff (24
0) may be left unprocessed for a long time. To solve this problem, there is a method that adds priority processing.

In explaining the priority processing, as an example, the priority range is assumed to be an integer from 1 (low priority) to 5 (high priority). Furthermore, a command newly added to the command queue is given an initial priority of 1.

Now, the current command queue order and priority are
Assume that it is as shown in the figure. Here, when the priority processing shown in FIG. 2 is passed, the priority is set to +1 for all queues in the command queue. At this time, the third
In the command queue shown in the figure, commands whose priority reaches the maximum value of 5 (■ in Figure 3) are considered to have been left unprocessed for a long time, and are given a special priority of S. can be ranked. Furthermore, for commands that are lined up before this one in the command queue (■ in Figure 3), regardless of their current priority, all commands are set to priority S and are used for the next distance calculation process. Avoid sorting processing. In other words, only commands with priority S or lower are rearranged. (See Figure 4 (B)) By doing this, commands with priority S will be processed first, and at the same time, no commands will be left unprocessed. The optimization of the processing (seek operation) is maintained.

〔Effect of the invention〕

As explained above, the present invention shortens the total movement distance of the head by changing the execution order of commands through simple processing. However, it has the excellent feature of efficiently processing and shortening the execution time.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a disk, FIG. 2 is a flow chart of optimization processing, FIG. 3 is a diagram showing an example of an input command queue, and FIG. 4 is a diagram showing an example of a rearranged output command queue. FIG. 5 is a configuration diagram of a storage device according to the present invention. 11...Head 12...Disk surface 13...Storage device (Disk device) that performs seek operation
14...Host computer 15...Disk1ilJ control device 16...Command queue, and above

Claims (2)

[Claims] (1) In a device including one or more storage devices that involve a seek operation, and a plurality of commands that involve a seek operation that control the storage device, the position of the head of the storage device and the commands are determined. The method is characterized in that the distance between the head and each command is calculated and the commands are rearranged by sorting in order to perform an optimal seek operation of the head from a cylinder in which the head must be located in order to execute the command. A storage device seek control method. (2) In the seek control method for a storage device, the commands are prioritized, and the commands are rearranged including the priority in distance calculation and sorting processing. Method.