JPS6318580A - Multiarm type disk file system - Google Patents

Abstract

PURPOSE:To apply no influence to respective file access speeds even when the file accesses from plural processes compete by making a disk a multiarm type, reserving an arm according to a request from a user program every time for opening a file and releasing the reserved arm every time for closing the file. CONSTITUTION:The plural arms 2a, 2b, 2c capable of being independently operated and controlled are provided in the movable head disk 1 and when the file is opened, the arms 2a, 2b, 2c can be reserved according to the request from a user process. Thereafter, data in the file is made access according to a file read and a write commands and the arms 2a, 2b, 2c are reserved, so that the data is not moved by other cylinder according to other competing file access command. Accordingly, even when the plural file access commands compete, the individual file access command have the same speed as the case when the file is made access by itself.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk file system constituting an operating system. In such a disk file system, it is desirable to maintain fast and continuous file access to the disk in order to improve the performance of the computer system.

[Conventional technology]

During actual operation of a computer system, many user processes (user programs) run in parallel under the operating system. Under this situation, from the user process to the file system (file processing process),
File access requests arrive at the same time. In other words, an open or close operation from another user process may occur between the time the file is opened and the time the file is closed.

The structure of a typical disk file system is shown in Figure 2. In the figure, 1 is a disk and 2 is an arm.

Now, multiple files (File ■, File ■ in the figure) on the single-arm movable head disk shown in the same figure.
The operation when file access requests from a plurality of user processes occur simultaneously for K will be described with reference to FIG.

(1) When user process A accesses file ■, first open the file (see Figure 3 ■)
. - When opening this file, common table preprocessing such as identifying the file size is performed, and then a specific record is read (random access). At this time, individual files are often arranged in contiguous areas on the disk to improve access efficiency. By this read operation, the arm first seeks (moves the arm in the radial direction) to the target cylinder position (see 2), and then reads the data (see 2). The write operation is also performed in the same manner as above (see 2), and then a predetermined post-processing is performed and the file is closed (see 2).

(2) Next, in order to access file ■, user process B first opens the file, and then
Read a specific record (random access). In other words, a file open operation is performed every time the file changes. In this case, data is read after the arm is sought from a specific position in file ■ to a specific position in file ■.

In (3) and ~, when the user process attempts to access a specific record in file ■ again, the arm is at a specific position in file ■, so it must seek first. In other words, a waiting time occurs due to the seek, and this waiting time depends on the distance between the cylinders.

[Problem that the invention seeks to solve]

As described above, when multiple user processes access multiple files on the same disk at the same time, there is a problem in that the access arm frequently moves back and forth between files, reducing the speed of disk access.

Therefore, it is an object of the present invention to prevent each file access speed from being affected even when file accesses from multiple processes compete.

[Means for solving problems]

When a disk is made into a multi-arm type, an arm is reserved each time a file is opened according to a request from a user program, and the reserved arm is released each time a file is closed.

[Effect]

(1) Operates independently in a movable head disk.

Provide multiple controllable arms.

(2) To be able to reserve an arm in response to a request from a user process when opening a file.
do.

(5) After this, the data in the file is accessed by file read and write commands. Since the arm is reserved at this time, it will not be moved to another cylinder by another conflicting file access command.

Therefore, even when multiple file access commands compete, each file access command has the same speed as when only the user is accessing the file.

(4) When a file is closed, the reserved arm is released as a free resource (release state).

[Embodiments of the invention]

FIG. 1 is an explanatory diagram for explaining the invention in detail. As shown in FIG. 1(a), a disk file system having two reservable arms 2a, 2b and one non-reservable arm 2C will be explained as an example.

In general, in computer systems, multiple accesses to files proceed simultaneously using the multi-process control function of the operating system. Also,
In today's large-capacity disks, multiple files are often stored on the same disk (recording medium). Therefore, in this embodiment, a file area is acquired by a file utility when offline (during system maintenance), and the utility generates files on consecutive cylinders as much as possible.
If this is not possible, try to generate them on adjacent cylinders as much as possible.

In such a configuration, during online operation, file access requests will be received from many user processes to the file system, and file access will be performed in the same way as shown in Figure 3. Each arm should have a reserve and release management table. An example of this table is
Shown in Figure (b). Here, "11 indicates a reserve state, and 10m indicates a release state. Then, when a user process requests file access to the file system, it requests the arm to be reserved at the same time. When the file system accepts the request, it searches for an arm in a released state by referring to the arm management table shown in Figure 1 (b) during a series of file open processing steps, and selects a free arm with the corresponding access command. Reserve (allocate) to.If there is no request for reservation, allocate arm 2C, which cannot be reserved, to the access command, and share the arm with several access commands thereafter.Once the arm is reserved, , the reserved state is maintained until the file is closed.Thus, for example, if user process B reserves arm 2a to access file 0 and user process B reserves arm 2b to access file ■. , and other user processes do not require high-speed processing, so they will use arm 2C, which cannot be reserved.

As a result, even if file access conflicts between the process and process B, the wait time due to seek does not increase compared to the single-arm case. Note that the reserved arm is released as a free resource when the file is closed.

〔Effect of the invention〕

According to this invention, for a disk having a plurality of independently controlled hanging arms, the arms can be exclusively used for individual file access commands, so the movement of the arms can be suppressed within the same file, and the seek time can be reduced. be shortened. Therefore, the advantage of faster file access is provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the invention in detail, and FIG.
The figure is a schematic diagram showing a typical disk file system,
FIG. 3 is a flowchart for explaining the operation. Code explanation 1...disc, 2+2a*2tz2c...
...Arm,■,■...File/Agent Patent attorney Akio Namiki Agent Patent attorney Kiyoshi Matsuzaki Figure 1 (B)

Claims (1)

[Scope of Claim] A multi-arm disk file system comprising a plurality of data files and a plurality of arms that can be controlled independently of each other, and which constitutes an operating system, wherein the file system is configured to: A multi-arm disk file system is characterized in that an arm is reserved in response to a request from a request source (user program), and the reserved arm is released each time a file is closed.