JP3183984B2 - File access control device for low-speed devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file access control device for a low-speed device for reading / writing a data file from / to a large-capacity and low-speed external auxiliary storage device such as an optical disk or a magneto-optical disk.

[0002]

2. Description of the Related Art In general, in a distributed computer system in which a plurality of workstations are connected to a server computer such as a workstation server or a minicomputer, a high-speed auxiliary storage device such as a magnetic disk built in or connected to the server computer. Since the storage capacity of the data file is insufficient with only the above, a low-speed external auxiliary storage device such as an optical disk or a magneto-optical disk is further connected.

[0003] When a plurality of workstations request to read or write different data files at substantially the same time to a server computer, if the medium to be read or written is the high-speed auxiliary storage device, Access processing of a data file is executed at substantially the same time as the apparent appearance of the data file. However, for the low-speed external auxiliary storage device, a read or write request given to the server is accepted and processed one by one. If an access request to the external auxiliary storage device is received from another user while accessing the external auxiliary storage device based on a request from the user, a message such as "accessing" is returned to this user from the server side. Wait for this “accessing” message to disappear and send an access request to the server again. There is a need.

That is, in the above-mentioned distributed computer system, when a plurality of users access a data file to the large-capacity and low-speed external auxiliary storage device, conventionally, for example, in response to a status message from a server computer. However, the user himself controls the access timing artificially.

[0005]

Therefore, access requests from a plurality of users are sequentially received and stored in a server computer, and read or write processing is sequentially performed in accordance with the stored contents, whereby timing control in a human system is performed. Can be omitted, for example, even if a new access request is given while some access requests are stored in advance, the execution of the request is performed until the processing of the preceding request is sequentially completed. There is a problem that the waiting point is not improved at all.

In this case, even if there is some waiting time in the execution of the processing for the data file write request inside the server computer, there is little adverse effect on the progress of the processing on the user side, so this is an important problem. However, if there is a long waiting time until the execution of the read request, there is a direct effect such as a delay in processing on the user side, which hinders speeding up data processing.

[0007] The present invention has been made in view of the above problems,
A file access control device for a low-speed device capable of executing read processing at the maximum speed without waiting and processing sequentially as requested in response to data file read / write requests from a plurality of users. The purpose is to provide.

[0008]

That is, a file access control apparatus for a low-speed device according to the present invention accesses a data file with a low-speed device in response to a read / write request from a plurality of users. Request receiving means for receiving read or write requests from a plurality of users; queue storing means for sequentially storing user requests received by the request receiving means as unprocessed queues; Device control means for controlling reading or writing of the data file to the low-speed device according to the first user request in the queue; and whether the user request obtained by the request receiving means and the queue storage means is a read request or a write request. Request determining means for determining whether a user request has been received by the request receiving means. It was when, to a user request is already a queue
In a case other than an access request to a certain data file, the request determination means determines that the currently accepted user request is a read request and the unprocessed user request already stored in the queue storage means is a write request. When it is determined by the above, a queue creating means for creating the queue by inserting the read request accepted this time before the unprocessed write request is provided.

[0009]

In other words, when the newly accepted user request is a read request, an access request to the same file is made.
With the exception of the above, the data file that is stored preferentially before the write request already existing in the queue, and the data file accompanying the read will be given to the requesting user as quickly as possible.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of a distributed computer system using a low-speed device file access control device.

In the above-mentioned distributed computer system, a server computer 11 is provided as a central processing unit.
The workstations WS1, WS2,... Of the respective users are connected to the server computer 11.

A high-speed auxiliary storage device (not shown) such as a magnetic disk is built in the server computer 11, and a low-speed external auxiliary storage device 12 using, for example, an optical disk is connected to the server computer 11. .

A workstation WS owned by each user
.., WS2,.
Read and write data files as needed between the high-speed auxiliary storage device and the low-speed external auxiliary storage device 12 through the network. The data from the workstations WS1, WS2,... The request to read or write the file is given to the request receiving unit 13 of the server computer 11.

Here, the read request from the user includes information indicating that the request content is a read command, and information indicating a read target medium (for example, a disk number and its address).

The write request from the user includes:
Information indicating that the request is a write command, information indicating a write target medium (for example, a disk number and its address), and a data file to be written are included.

In the request accepting unit 13, the accepted user request is given to a queue creating unit 14, a request content judging unit 15, and a target media judging unit 16, respectively.

The queuing unit 14 receives the user request given from the request receiving unit 13 and obtains the request contents obtained from the request content judging unit 15 and the target media judging unit 16 and each of the request target media. Based on the judgment information, a queue of user requests that prioritizes reading of data files is created except for access requests to the same file. The queue of user requests created by the queue creating unit 14 is It is stored in the queue storage unit 17.

The queue of the user request stored in the queue storage unit 17 is read out as needed according to an instruction from the queue creation unit 14, and the request content determination unit 1
5 and the target media determination unit 16,
The external storage controller 18 sequentially reads the request from the request at the head of the matrix.

In other words, the request content judging unit 15 receives the current user request given from the request accepting unit 13 and the previous or last two-time user request given from the queue storage unit 17 in the waiting state. Is a read command or a write command. The determination information of the user request obtained by the request content determination unit 15 is given to the queue creation unit 14.

Further, the target media judging unit 16 receives the current user request given from the request accepting unit 13 and the previous or last two-time user request given from the queue storing unit 17 in the waiting state. The destination media information of the user request obtained by the target media determination unit 16 is determined by the queue creation unit 14.
Given to.

The external storage control unit 18 reads the first request of the user request queue created and stored in the queue storage unit 17 and reads the external auxiliary storage device (in this case, , An optical disk) 12, and the setting information of the requested medium is given to the external auxiliary storage device 12. For example, a plurality of optical disks A to D are selectively set as the access target media. .

The read or write instruction information from the external storage control unit 18 is supplied to an R / W (write / read) control unit 19, and a read or write control signal is supplied to the external auxiliary storage device 12. You.

As a result, data files are read from or written to the optical disks A to D according to the user's request of the external auxiliary storage device 12. For example, the data file read from the external auxiliary storage device 12 is
Are output from the server computer 11 via the / W control unit 19, and the workstations WS1, WS2,.
Is forwarded to Next, the operation of the distributed computer system using the low-speed device file access control device having the above configuration will be described. FIG. 2 is a flowchart showing a process of creating a queue of user requests by the file access control device of the low-speed device. FIG. 3 is a flowchart showing a control process of the external auxiliary storage device by the file access control device of the low-speed device. FIG. 4 is a diagram showing a state of accepting and executing a user request by the file access control device of the low-speed device.

That is, after starting the distributed computer system, for example, first, the workstation WS
When a request 1 for writing a data file to the medium A is given to the request receiving unit 13 of the server computer 11, the write request 1 is immediately stored in the queue storage unit 17 through the queue creating unit 14 and the external storage control. The data is read by the unit 18 (step P1).

Then, the optical disk A of the external auxiliary storage device 12 is set as a medium to be accessed, and the R / W control unit 19 sends the external auxiliary storage device 12 to the external auxiliary storage device 12 based on the write instruction information from the external storage control unit 18. A write control signal is supplied and the workstation WS
The writing process of the data file to the optical disk A in accordance with the writing request 1 from the P.1 is executed (step P
2, P3 → P5).

Thereafter, when the write processing in accordance with the write request 1 is completed, the write request 1 is deleted from the queue storage unit 17, and the write request 1 is placed in the queue storage unit 17 in a waiting state. If there is some next request,
Access processing of the data file according to the request is started (steps P5, P6 → P1).

On the other hand, in the execution state of the write request 1 in the step P5, for example, the workstation W
When a request 2 for writing a data file to the medium B from S2 is given to the request accepting unit 13, the request 2 is queued as an unprocessed request at the head of the queue following the write request 1 being executed through the queue creating unit 14. It is stored in the matrix storage unit 17.

In this way, with an unprocessed queue (write request 2) generated in the queue storage unit 17,
For example, when a request 3 for reading a data file from the workstation WS3 to the medium C is given to the request accepting unit 13, the process of creating a request queue in the queue creating unit 14 is started. In, it is determined whether or not the requested content is a read command (step S1 → S2).

If "YES" is determined in step S2, that is, if the content of the request accepted this time is a read command, the queue "(write request 1: (Under execution) → (write request 2: unprocessed) ”, and the request content determination unit 15 reads the request content of the previous reception (in this case, request 2).
Is a write request that is not an access request to the same file (steps S2 → S3, S4).

In this step S4, "YES", that is, it is determined that the content of the request 2 of the previous reception is a write, and that it is not a request to access the same file.
Then, when it is confirmed that the current read request 3 should be given priority over the previous write request 2, further, based on the access target medium for each request obtained by the target medium determination unit 16, the reception before the last time is performed. Whether the access target medium corresponding to the request 1 is the same as the access target medium corresponding to the request 3 received this time, that is, the setting change of the access target medium occurs when it is assumed that the request 3 is processed following the request 1 It is determined whether or not there is (Step S4 → S5).

In this step S5, "No", that is, the access target medium A of the write request 1 which is currently being executed in the reception two times before and the access target medium B of the read request 3 which is currently received are different from each other. If it is determined that the setting of the medium needs to be changed, it is further determined whether the access target medium corresponding to the request 2 of the previous reception and the access target medium corresponding to the request 2 of the previous reception are different, The queue “(write request 1: already stored in the queue storage unit 17)
Even if the access process of the data file is executed with “executing” → (write request 2: unprocessed), the write request 1
It is determined whether or not the setting of the access target medium is changed as in the case where the continuous processing of the read request 3 is assumed (steps S5 → S6).

In this step S6, "YES", that is, the access target medium A of the write request 1 which is being executed in the reception two times before and the access target medium B of the write request 2 which was received the previous time are different from each other. Even if the access process is executed, if it is determined that the media setting needs to be changed, the previously accepted write request 2
, The read request 3 received this time is preferentially replaced and inserted, and a new queue “(write request 1: executing) → (read request 3: unprocessed) → (write request 2: unprocessed) Is stored in the queue storage unit 17 (steps S6 → S7).

In this manner, a new request queue “(write request 1: executing) → (read request 3: unprocessed) → (write request 2: unprocessed)” is created, and the queue storage unit 17
When the process of writing the data file to the optical disk A of the external auxiliary storage device 12 in accordance with the currently executed write request 1 is completed in the state stored in the queue, the next head request (read request 3) in the queue is sent. The data is read by the external storage control unit 18, the optical disk C of the external auxiliary storage device 12 is changed and set as the access target medium, and the R / W
A read control signal is supplied from the control unit 19 to the external auxiliary storage device 12, and before the write request 2 from the workstation WS2, a process of reading a data file from the optical disk C according to the read request 3 from the workstation WS3 is performed. Priority is given to execution (step P5,
P6 → P1 to P3 → P4).

When the read process according to the read request 3 is completed, the next head request (write request 2) in the queue is read by the external storage control unit 18 and the external auxiliary storage device 12 is read. The optical disk B is changed and set as an access target medium, and a write control signal is supplied from the R / W control unit 19 to the external auxiliary storage device 12 based on the write instruction information from the external storage control unit 18. The process of writing the data file to the optical disc B in accordance with the write request 2 from the station WS2 is executed (steps P4, P6 → P1.
P3 → P5).

On the other hand, for example, the medium to be accessed corresponding to the read request 3 is the medium A, and "YES" in the step S5, that is, the medium A to be accessed of the write request 1 currently being executed two times before and the current time If it is determined that there is no change in the media setting when it is assumed that the access target medium A of the read request 3 is the same and continuous processing is performed, the write request 1 received two times before and the write request 2 received last time are determined. Regardless of the difference between the media, the read request 3 received this time has priority, and the read request 3 received this time is inserted before the write request 2 received last time in the same manner as described above (step S5 →
S7).

On the other hand, in step S4, "N
O ", that is, even if the user request received this time is a read request, if it is determined that the user request received last time is not a write request but a read request, the previous read request Since the read request of the reception is prioritized, the read request of the current reception is stored following the read request of the previous reception (step S4 → S
8).

In step S6, "N
O ", that is, the user request received this time is a read request, and the user request received last time is a write request,
Even if it is determined that the read request received this time should be prioritized, the media requested two times before and the media requested this time are different, and the media requested two times before and the media requested last time are the same. If it is determined, the processing with less media change is prioritized, so that the read request of the current reception is stored following the write request of the previous reception (step S6 → S8).

On the other hand, in step S2, "N
O ", that is, when it is determined that the user request received this time is a write request, it is determined whether the user request received last time is a read request (steps S2 → S9).

If "YES" in this step S9, that is, if it is determined that the user request of the last reception is read, the read request of the last reception is naturally given priority, and the write request of the current reception is left as it is. Stored following the previously received read request (step S9 → S
8).

In step S9, "N
O ", that is, if the currently accepted user request is a write and the previous accepted user request is also a write, the access target medium corresponding to the user request of the last-last accepted and the access target corresponding to the previously accepted write request Whether or not the media is the same, that is, even if the access process of the data file is executed with the current request queue, the setting change of the target media occurs between the request process of the last reception and the request process of the previous reception. It is determined whether or not there is (Step S9 → S10).

"YES" in this step S10,
That is, the user request medium received two times before and the write request medium received last time are the same, and even if the write request received this time and the write request received last time are exchanged, there is no advantage in speeding up the processing. Is determined, the write request received this time is stored directly after the write request received last time (step S10 → S
8).

On the other hand, in step S10, "N
O ", that is, it is determined that the user request medium of the second-last reception and the write request medium of the last reception are different, and the setting change of the target medium is necessary between the request processing of the second-last reception and the request processing of the last reception. In the case, it is further determined whether the user request medium received two times before and the write request medium received this time are the same, that is, the setting of the medium to be accessed when it is assumed that the current write request has been processed following the user request two times before It is determined whether or not a change occurs (step S10 → S11).

"YES" in this step S11,
In other words, if the user request medium received two times before and the write request medium received this time are the same, and the target write medium is replaced with a different write request received last time,
If it is determined that there is an advantage in speeding up the processing, the write request received this time is preferentially replaced and stored before the write request received last time (steps S11 and S1).
2).

On the other hand, in step S11, "N
O ", that is, the previous write request and the current write request are different from each other. The previous write request and the current write request are different from each other. However, if it is determined that the write request does not contribute to speeding up of the processing at all, the write request of the current reception is stored as it is following the write request of the previous reception (step S11 → S
8).

Therefore, according to the file access control device of the low-speed device having the above configuration, the read or write request from each of the workstations WS1, WS2,. If the request is a read request, the previously accepted user request already stored in the queue storage unit 17 in the waiting state is the access to the same file.
This is a write request that is not a request, and the read request medium received this time is the same as the user request medium received two times before, or the read request medium received this time is different from the user request medium received two times before, but the write request medium received last time Is different, the queue creation unit 1 is based on the content judgment and the media judgment information for each reception request from the request content judgment unit 15 and the target media judgment unit 16.
At 4, the read request received this time is preferentially replaced and inserted before the write request received last time, and stored as a new queue in the queue storage unit 17.
7 are sequentially read to the external storage control unit 18 and the optical disk A of the external auxiliary storage device 12 is read out.
To D are selectively set, and a read or write control signal from the R / W control unit 19 is used to read or write a data file to or from the set optical disk. The processing can be performed as fast as possible without adversely affecting the setting processing, and the delay in user processing is greatly reduced, and the speed of data processing can be increased.

In the above embodiment, the case where an optical disk is used as the low-speed external auxiliary storage device 12 has been described. However, the same applies to an external auxiliary storage device using a magneto-optical disk or a magnetic tape. A file access control device of a low-speed device can be applied.

[0047]

As described above, according to the present invention, a data file is accessed with a low-speed device in response to a read / write request from a plurality of users. A request receiving means for receiving, a queue storing means for sequentially storing the user requests received by the request receiving means as an unprocessed queue, and a first user request in a queue stored in the queue storing means. Device control means for controlling reading or writing of a data file to the low-speed device; request determination means for determining whether the user request obtained by the request reception means and the queue storage means is a read request or a write request; When the user request is received by the request receiving means, the user request is already in the queue.
In the case other than the access request to the data file, the request determination means determines that the currently accepted user request is a read request and the unprocessed user request already stored in the queue storage means is a write request. If the determination is made by the following, the queue includes a queue creation means for creating the queue by inserting the read request accepted this time before the unprocessed write request. In response to a file read / write request, the read process can be executed at a maximum speed without being waited and processed sequentially as requested.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing the configuration of a distributed computer system using a file access control device for a low-speed device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a process of creating a user request queue by the file access control device of the low-speed device.

FIG. 3 is a flowchart showing control processing of an external auxiliary storage device by the file access control device of the low-speed device.

FIG. 4 is a diagram showing a state of accepting and executing a user request by the file access control device of the low-speed device.

[Explanation of symbols]

11: server computer, 12: external auxiliary storage device,
13 request receiving unit, 14 queue creating unit, 15 request content determining unit, 16 target media determining unit, 17 queue storage unit, 18 external storage control unit, 19 read / write (R / W) ) Control unit, WS1, WS2, ... workstation.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 3/06 G06F 12/06 550

Claims (2)

(57) [Claims] 2. A file access control device for a low-speed device for accessing a data file with a low-speed device in response to a read / write request from a plurality of users, wherein the request receiving means receives a read or write request from the plurality of users. Queue storage means for sequentially storing the user requests received by the request reception means as unprocessed queues; and a low-speed device for the low-speed device according to the first user request in the queue stored in the queue storage means. Device control means for controlling the reading or writing of the data file; request determination means for determining whether the user request obtained by the request reception means and the queue storage means is a read request or a write request; when the user request has been accepted Te, Yu
User request to access a data file already in the queue
In the case other than the access request, the request determination unit determines that the currently accepted user request is a read request and the unprocessed user request already stored in the queue storage unit is a write request. And a queue creation means for creating the queue by inserting the currently accepted read request before the unprocessed write request. 2. A file access control device for a low-speed device for accessing a data file with a low-speed device in response to a read / write request from a plurality of users, a request receiving unit for receiving a read or write request from the plurality of users. Queue storage means for sequentially storing the user requests received by the request reception means as unprocessed queues; and a low-speed device for the low-speed device according to the first user request in the queue stored in the queue storage means. Device control means for controlling the setting of an access target medium and reading or writing of a data file with respect to the set medium; and determining whether the user request obtained by the request receiving means and the queue storing means is a read request or a write request. Request content judging means; Media determination means for determining an access target medium corresponding to the user request obtained by the matrix storage means; and when the user request is received by the request reception means, determination is made by the request content determination means and the media determination means. Creates an unprocessed queue to be stored in the queue storage unit based on the contents of each of the currently accepted user requests and the unprocessed user requests already stored in the queue storage unit and the media to be accessed. A file access control device for a low-speed device, comprising: