JPH09212405A - Method and device for file management - Google Patents

Abstract

PROBLEM TO BE SOLVED: To structure a system which flexibly makes it possible for a client to register, update, and take out common irregular form information. SOLUTION: When a request to refer to a file held on a server is made, it is decided whether or not the reference request is made by a client or user. According to the decision result, the version of a file which were taken out in the past is retrieved and compared with the version of the file held on the server. When it is judged that the version of the file held on the server is newer than the retrieved version, reference information is transmitted in client or user units according to the decision result obtained in the decision step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file management method for registering / updating / retrieving atypical information shared by a plurality of terminals. The file management in this specification manages non-standardized information such as documents, drawings and other information as a file.

[0002]

2. Description of the Related Art Conventionally, there are the following two methods for managing files in a client / server system. One is that each client manages the information about the file that the client retrieves and holds, and when each client accesses the server, it uses the update information of the file on the server that the server has. , The old and new files on the client are judged, and the file is transferred from the server.

Another is that the server manages the version information of the file held by the client, and the software stored in the server is collectively delivered to the client according to an instruction from the server. . Also, the conventional file management method for balancing the load of resources by shared files is to automatically select a disk or server with a low load when a client accesses a file that has been distributed in advance. , Load distribution was done.

An example of the first method of managing the information of the files held by the clients by each client will be described. FIG. 14 shows, for example, Japanese Patent Laid-Open No. 5-1
It is a block diagram which shows the conventional file management system described in 81733. The conventional file management system in FIG. 14 has a host device 51 and a terminal 52 that transmit and receive a telegram via a network, a file storage unit 512 that stores files of the host device 51, and a file of the terminal 52. File storage unit 522.

The operation of this file management system will be described. When the terminal 52 is connected to the host device 51, the management information is received from the host device 51, and the management information of the host device 51 is compared with the management information of its own terminal in the comparison processing unit 524. As a result of the comparison, when the management information of the higher-level device 51 and the management information of its own terminal are different, the terminal 52 requests the higher-level device 51 to transfer the corresponding file, and the higher-level device 5
1 receives a transfer request from the terminal 52, and transmits a file to be updated by the terminal 52 to the terminal 52.

Next, an example of a second method of managing information of files held by the client by the server will be described. FIG. 15 shows, for example, Japanese Patent Laid-Open No. 4-287222.
5 is a configuration diagram showing a conventional file management system described in FIG. The conventional file management system in FIG. 15 includes a terminal device 61 including a CRT and a keyboard, a terminal load module library 62, a load module receiving means 63, a load module transfer means 64, a host load module library 65, and a terminal load. Module revision management means 66 and host connection terminal 6
7 and a host computer 68.

The operation of this file management system will be described. The software developer or administrator uses the terminal load module revision management means 66 from the host connection terminal 67 to determine the load module name and terminal name to be transferred this time. The terminal load module revision management means 66 manages the load module name installed in each terminal and its revision.

Next, the load module transfer means 64 operates, retrieves the load module name determined above from the host load module library 65, and transfers it to each terminal according to the terminal name. The load module receiving means 63 writes the load module transferred from the host into the terminal load module library 62. The transfer status is the load module receiving means 63 and the load module transferring means 64.
Through the terminal load module revision management means 66
When the transfer is normally completed and the transfer is normally completed, the management information of each terminal device is updated.

An example of load balancing in the distributed database management method will be described. FIG.
FIG. 1 is a configuration diagram showing a conventional file management system described in, for example, Japanese Patent Laid-Open No. 6-259308. A load table 720 for each of the servers 711 to 714 in FIG.
Alternatively, by providing the usage status table 730 in any of the clients 711 to 713, the transceiver 75, and the router 74, for example, when the same information is redundantly managed by a plurality of servers 711 to 714, A server with the lowest load among 711 to 714 or a server with a large amount of free information storage medium is selected so that the load can be distributed without the user being aware of it.

[0010]

However, the conventional file management system has the following problems. In the first file management method disclosed in Japanese Patent Laid-Open No. 05-181733, which is a client-based file management method, when each client logs in to the server, all the retrieved files are compared with the information held by the server. The client had to choose whether or not to update each file in order to log in to the server. Among the extracted files, there should be some files that require the latest version and some files that do not, but it was not possible to specify in advance for each file whether or not to automatically transfer.

On the other hand, in the file management method disclosed in Japanese Patent Laid-Open No. 4-287222, which is a second server-based file management method, the server stores the load module name and revision currently held for each client. Since it manages information, it has the drawback that it can only be updated on a client-by-client basis. If you want to store non-standard information such as text files and image data instead of a load module of software that only needs to be held by the client, the information and version that each user wants to hold will be different. It is necessary to update not only client units, but also user units. For example, when one client is used by a plurality of users, or when one user accesses from a plurality of clients, the sharing method on a client-by-client basis poses a problem.

Further, in the conventional file management method disclosed in Japanese Patent Laid-Open No. 6-259308, data is originally distributed and stored in fixed locations, and when a client accesses the data, a load is applied. Since the servers to be accessed are selected so as to be distributed, it is not possible to change the data storage location later according to the state of the file. For non-standard information that is constantly registered / updated, the status of the server and disk changes constantly, but the conventional method has the drawback that it cannot deal dynamically with the situation. It was

That is, the conventional methods have the drawback that the usage conditions and usage methods are fixed, and there has been no method that can be managed comprehensively and deal flexibly.

The present invention has been made to solve the above problems, and is to construct a system capable of flexibly coping with registration / update / retrieval of shared atypical information from a client. With the goal.

[0015]

A file management method according to the present invention comprises a reference request step for requesting a reference of a file held in a server, a determination step for determining a request unit of the reference request, and a determination step described above. A search step for searching the version of the file extracted in the past according to the determined request unit type; a comparison step for comparing the version of the file held in the server with the version of the searched file; And a transmitting step of transmitting reference information according to the request unit determined in the determining step when the version of the file held in the server is newer than the version of the searched file in the comparing step. It is a thing.

A file management method according to the second invention is
The request unit is a client unit or a user unit. In the search step, if the determination result in the determination step is a client unit request, the version of the file extracted in the past by the client making the reference request. When the determination result in the determination step is a request for each user, the version of the file extracted in the past by the user who has issued the reference request is searched.

A file management method according to the third invention is
When the file held in the server is updated, a notification method setting step of setting the notification of the update of the file or setting of the updated file in response to the request from the client, and the notification or Depending on the subject setting step for setting changeable whether the transfer is performed by the client side or the server side, the subject determining step for determining the setting content in the subject setting step, and the determination result in the subject determining step A search step of searching for a client to whom the file has been updated or a transfer destination of the updated file, and a notification that the file has been updated to the client searched in the search step Alternatively, a transmission step for transferring the updated file And it has a.

A file management method according to the fourth invention is
In the search step, if the determination result in the subject determination step is the client side, the client that made the notification or transfer setting request in the notification method setting step is searched for the file for which the update request is made, and If the determination result in the subject determination step is the server-side subject, the client that retrieved the old version of the file for which the update request was made in the past is searched.

A file management method according to the fifth invention is
The server holds the file in response to the keyword registration step of registering the keyword corresponding to the information desired by the client, the holding request step of requesting the server to hold the file, and the holding request in the holding request step. A holding step, a keyword recognition step for recognizing a keyword attached to a file for which a holding request is made in the holding request step, and a keyword recognized in the keyword recognition step among the keywords registered in the registration step. It has a search step of searching for the corresponding keyword, and a holding notification step of notifying that the holding step has been executed to the client that has requested acquisition of information corresponding to the keyword searched in the searching step. That.

A file management method according to the sixth invention is
In the search step, the same keyword as the keyword recognized in the keyword recognition step is searched from the keywords registered in the registration step.

A file management method according to the seventh invention is
A retrieval request step in which the client requests retrieval of the file held in the server, a keyword recognition step of recognizing a keyword attached to the file requested in the retrieval request step, and a plurality of files retained in the server From the above, a search step of searching for a file corresponding to the keyword recognized in the keyword recognition step, and a search result notification step of notifying the client searched for the file searched in the search step Is.

A file management method according to the eighth invention is
Keywords are attached to the plurality of files stored in the server, and are the same as the keywords recognized in the keyword recognition step from the keywords attached to the plurality of files stored in the server in the search step. It searches for the keyword.

A file management method according to the ninth invention is
A holding request step for requesting holding of the file in the server and a plurality of files held in the server are searched for a file corresponding to the keyword attached to the file requested in the holding request step. A searching step; a selecting step of selecting whether to hold the file requested to be held in the holding request step in the server in association with the file searched in the searching step; and a selecting step in the selecting step. A holding step of holding the file for which the holding request is made in the server according to the selection result.

In the file management method according to the tenth aspect of the invention, the holding request in the holding request step is made by the client, and the selection in the selecting step is made by the client.

A file management method according to an eleventh aspect of the present invention is a file management method for managing access to a plurality of files held by a server, wherein information on the plurality of files stored in a storage device related to the server. A file stored in the storage device is stored in the storage device in accordance with a monitoring step for monitoring the amount, a load determination step for determining the load of the storage device from the monitoring result in the monitoring step, and a determination result in the load determination step. And a storage step of storing in a different storage device.

In the file management method according to the twelfth aspect of the invention, the monitoring of the information amount of the plurality of files in the monitoring step monitors the information in the first registration area in which the information amounts of the plurality of files are registered. It is done by.

A file management method according to a thirteenth invention is a file management method for managing access of a client to a plurality of files held by a server, wherein the client manages files stored in a storage device related to the server. A monitoring step for monitoring the access status of the server, a load determining step for determining the load on the server from the monitoring result in the monitoring step, and a file stored in the storage device according to the determination result in the load determining step. And a storage step of storing in a storage device different from the device.

According to the file management method of the fourteenth invention, the access status is monitored in the monitoring step.
This is performed by monitoring the information in the second registration area in which the time when the client has accessed the file stored in the storage device is registered.

A file management device according to the fifteenth invention is a file management device for managing access to a plurality of files stored in a server, and a storage means for storing the plurality of files stored in the server, The first registration area in which the information amounts of the plurality of files stored in the storage means are registered, and the information amounts of the plurality of files registered in the first registration area are monitored, and the above-mentioned information is stored according to the information amount of the file. The storage means has a management means for storing the file stored in the storage means in a storage means different from the storage means.

A file management apparatus according to the sixteenth invention is a file management apparatus for managing access of a client to a plurality of files held in a server, and a storage means for storing the plurality of files held in the server. And monitoring the second registration area in which the time when the client has accessed the plurality of files stored in the storage means is registered, and the time registered in the second registration area, and depending on the time. And a management means for storing the file stored in the storage means in a storage means different from the storage means.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. The file management system in this embodiment can refer to atypical information stored in the application server 1 in client units or user units, and will be described below with reference to FIGS. FIG. 1 is a block diagram of the file management system in this embodiment. In the figure, 1 is an application server connected to the network 6.
The application server 1 is for storing the substance of a shared atypical information file, and a magnetic disk device 10 described later is connected to the application server 1.

Reference numeral 2 denotes an attribute information database 21, which will be described later.
It is a management server that integrally manages the version management database 22 and the access history information database 23.
Reference numeral 20 denotes a magnetic disk device connected to the management server 2, and the magnetic disk device 20 stores an attribute information database 21, a version management database 22, and an access history information database 23 described later.

Reference numeral 21 is an attribute information database that manages the attribute information of the atypical information. Information stored in the attribute information database 21 includes an atypical information name, an atypical information storage location, and an atypical information version. Number, name of registrant of atypical information, registration date and time of atypical information, data size of atypical information, keyword indicating contents of atypical information, information related to atypical information including related atypical information, etc. .

Reference numeral 22 is a version management database for managing the version of the atypical information held by the application server 1. Reference numeral 23 is a database for managing access history information of atypical information registered / updated / retrieved by each client. The information stored in the access history information database 23 is, for example, access date and time, access processing content (information indicating whether registration / update / extraction), information indicating the client who accessed, information indicating the user who accessed. , The atypical information name that is the access target, the version number of the atypical information that is accessed, and the like. Reference numeral 24 is a keyword registration database, the details of which will be described later in an embodiment.

Reference numerals 3 to 5 are clients connected to the network 6, and the clients 3 to 5 request the management server 2 to newly register / update / take out atypical information. Reference numeral 10 denotes a magnetic disk device connected to the application server 1, and the magnetic disk device 10 stores an atypical information file 11. This file management system includes an application server 1, a management server 2, clients 3 to 5, a network 6, and a magnetic disk device 1.
It is composed of 0 and 20. Next, the internal configurations of the application server 1, the management server 2 and the client 3 in this embodiment will be described with reference to FIG.

FIG. 2 is an internal block diagram of the file management system. As shown in FIG. 2, the application server 1 includes a file access unit 15, a transmission processing unit 16 and a reception processing unit 17. The file access unit 15 is connected to the magnetic disk device 10, the transmission processing unit 16, and the reception processing unit 17. The transmission processing unit 16 is connected to the network 6 and performs a process for outputting information to the network 6. The reception processing unit 17 is connected to the network 6 and performs processing for receiving information from the network 6.

The management server 2 has a database management unit 25.
And a transmission processing unit 26 and a request reception processing unit 27. The database management unit 25 is connected to the magnetic disk device 20, the transmission processing unit 26, and the request reception processing unit 27. The transmission processing unit 26 is connected to the network 6 and performs a process for outputting information to the network 6. The request reception processing unit 27 is connected to the network and performs processing for receiving request information from the client 3 via the network 6.

The client 3 comprises a receiver 31 and a request transmitter 32. The receiving unit 31 is the network 6
Connected to perform processing for receiving information. The request transmission unit 32 is connected to the network 6 and performs processing for transmitting request information to the management server 2 via the network 6.

Next, the operation of the file management system in this embodiment will be described with reference to FIGS.
FIG. 3 is a flowchart showing the flow of processing of the management server 2 in this embodiment. A case will be described in which one of the clients 3 to 5 connected to the network 6, for example, the client 3 issues a reference request for atypical information. In this reference request, information indicating which atypical information is referred to, information indicating whether the reference request is a client unit or a user unit, and information indicating a requesting client name or user name are transmitted. To do. This reference request is transmitted from the request transmission unit 32 to the management server 2 via the network 6. Here, the reference means to see what kind of atypical information is stored in the application server 1, specifically, to see the atypical information name stored in the application server 1, Refers to the contents of specified atypical information.

The request reception processing unit 27 of the management server 2 receives the reference request from the client 3 (S1).
1) It is determined whether the request is a client-based reference request or a user-based reference request (S12).

If the result of the determination in S12 is a reference request in client units, the following processing is performed. The request reception processing unit 27 passes the determination result in S12 to the database management unit 25, and the database management unit 2
5 retrieves the atypical information name retrieved by the client 3 in the past from the access history information database 23 and its version (S13).

The database management unit 25 compares the search result of S13 with the version of the atypical information held by the application server 1 (S15), and determines whether the version of the application server 1 is newer (S16). ). The version of the atypical information held by the application server 1 is the attribute information database 21.
It can be recognized from the version number of the atypical information which is the information stored inside.

The database management unit 25 passes only the atypical information of which the application server 1 is a newer version to the transmission processing unit 26, and the transmission processing unit 26 notifies the client 3 of the atypical information name of the new version ( S17). Since this method can be referred to on a client-by-client basis, for example, in the client 3,
The same reference result can be obtained regardless of whether user A or user B references. Therefore, one client is one
This is useful when you want to obtain new version information for software that you retain.

If the result of determination in S12 is a reference request for each user, the following processing is performed. The database management unit 25 searches the access history information database 23 for the atypical information name retrieved by the user in the past and its version (S14).

Then, the database management unit 25 compares the retrieved result with the version of the atypical information held by the application server 1 (S15) to determine whether the version of the application server 1 is newer. (S16). The version of the atypical information held by the application server 1 can be recognized from the version number of the atypical information, which is the information stored in the attribute information database 21.

The database management unit 25 passes only the non-stereotyped information, which is the newer version of the application server 1, to the transmission processing unit 26, and the transmission processing unit 26 issues a reference request for the non-stereotyped information name of the new version. (S17). Since this method can be referred to on a user-by-user basis, regardless of whether the user A refers to the client 3 or the client 4, regardless of the information held by the clients 3 and 4, the same reference result is obtained. Is obtained. Therefore, it is effective in a case where it is desired to obtain new version information about atypical information that each user personally takes out and retains, rather than atypical information that one client holds.

In the file management method in this embodiment, reference is made in client units or user units. However, the unit for making a reference request is not limited to client units or user units, and other request unit types are supported. You may allow it. Specifically, for example, it is possible to respond to the reference request on an individual user basis or a user group basis.

Embodiment 2 The file management system in this embodiment performs automatic notification or automatic transfer indicating that the atypical information on the application server 1 has been updated, when the atypical information on the application server 1 is updated to a new version. Description will be made based on 1, 2, 4, and 5. The configuration of the file management system in this embodiment is the same as the management system in the previous embodiment shown in FIGS.

Next, the operation of the file management system in this embodiment will be described with reference to FIGS. Regarding the atypical information that the clients 3 to 5 always want to keep the latest version, when the atypical information on the application server 1 is updated to a new version when extracting the atypical information, an automatic notification or an automatic notification is performed. The management server 2 is set in advance to be transferred. Further, the clients 3 to 5 can set in advance in the management server 2 whether to extract the atypical information in client units or in user units.

Next, the operation when the management server 2 receives an automatic notification / automatic transfer setting request from a client will be described with reference to FIGS. 1, 2, and 4. In FIG. 4, in this embodiment, the management server 2 has the clients 3 through 3.
5 is a flowchart showing the flow of processing when an automatic notification / automatic transfer setting request is received from S5. For example, it is assumed that the client 3 issues an automatic notification / automatic transfer setting request to the management server 2 when the version 3 of the atypical information A is taken out. At the time of this setting request, information indicating whether the setting request is on a client basis or a user basis, and information indicating whether automatic notification or automatic transfer is requested are transmitted.

When the request reception processing unit 27 of the management server 2 receives an automatic notification / automatic transfer setting request from the client 3 (S21), whether the request is a client unit request or a user unit request. Is determined (S2
2).

Then, as a notification method, it is determined whether the method is a method of notifying only atypical information, or a request for automatic transfer (S2).
3). The request processing result is passed to the database management unit 25,
The database management unit 25 uses the attribute information database 21.
Regarding the atypical information A, the request is registered on a client basis or a user basis, and whether the notification method is automatic notification or automatic transfer is registered (S24).

By the above procedure, the request from the client is set in the management server 2 in advance. In this embodiment, the case has been described where the client 3 issues an automatic notification / automatic transfer setting request for each client, but it is also possible to issue an automatic notification / automatic transfer setting request for each user.

Next, the operation when the management server receives an update request from the client after the automatic notification / automatic transfer is set will be described with reference to FIGS. 1, 2, and 5. FIG. 5 is a flowchart showing the flow of processing when the management server 2 receives an update request in this embodiment.

For example, assuming that the atypical information A currently stored in the magnetic disk device 10 of the application server 1 is version 3, and there is a request from the client 5 to update the atypical information A to version 4. explain. When the request reception processing unit 27 of the management server 2 receives the update request from the client 5 (S31), the reception processing result is passed to the database management unit 25, and the database management unit 25 transmits the storage request to the transmission processing unit 26. Instruct. The transmission processing unit 26 issues a storage request for the non-standard information A requested to be updated to the application server 1 (S32). Upon receiving the storage request, the reception processing unit 17 of the application server 1 notifies the file access unit 15 and the file access unit 15 stores it in the magnetic disk 10. As a result, the atypical information A stored in the magnetic disk device 10 is updated from version 3 to version 4.

Database management unit 25 of the management server 2
Determines from the attribute information database 21 whether the atypical information A is to be notified / transferred to the client by the server side entity or to be notified / transferred to the client by the client side entity (S33). Whether to notify / transfer to the server-side subject or to notify / transfer to the client-side subject is preset.

If the information is atypical information to be notified / transferred by the client side, the attribute information database 21 is searched for a client and a user for which an automatic notification / automatic transfer request is set (S34). As a result, it is searched that the client 3 has issued the automatic notification / automatic update request. Further, since the notification method is also registered in the attribute information database 21, the notification method is set to a method of notifying the atypical information (not the substance of the atypical information) (update notification only) or set to be automatically transferred. It is determined whether it has been done (S36).

If the automatic notification is set, the transmission processing unit 26 sends the atypical information A to the client 3.
Sends an update notification notifying that the has been updated to version 4 (S37). If automatic transfer is set, the transmission processing unit 26 issues a transfer request to the application server 1 (S38). When the reception processing unit 17 of the application server 1 receives the transmission request, the file access unit 15 extracts the new version 4 of the atypical information A from the magnetic disk 10 and transfers it to the client 3.

Thereafter, the database management unit 25 of the management server 2 stores the atypical information name, storage location, version number, and registrant name of the atypical information in the attribute information database 21 as the attribute information regarding the updated atypical information. , Registration date and time, data size of atypical information, etc. are added (S39),
The access history information database 23 stores necessary data such as update date and time, information indicating the updated client, information indicating the updated user, and the updated version number as the update history (S310).

The effect of the file management method in this embodiment will be described. In the file management method according to this embodiment, when the atypical information on the application server 1 is updated to a new version, an automatic notification indicating that the atypical information is updated or updated atypical information Can be automatically transferred. In addition, the client can set whether to perform automatic notification or automatic transfer, so that a flexible file management system can be configured.

Further, since it is possible to set automatic notification or automatic transfer on a user-by-user basis for non-standard information that is owned by an individual and does not depend on a client, a plurality of users can use one client. Even in the case, it is possible to respond to the request of each user.

Furthermore, in this embodiment, each client issues an automatic notification / automatic transfer setting request for some of the non-standard information stored in the magnetic disk device 10 of the application server 1. Therefore, automatic notification or automatic transfer can be performed only for atypical information that requires the latest version.

In the file management method according to this embodiment, it is possible to select whether to notify / transfer the non-standard information by the client side or the server side. Can also respond. Therefore, a flexible file management system can be configured.

Embodiment 3 The file management system in this embodiment performs automatic notification or automatic transfer indicating that the atypical information on the application server 1 has been updated, when the information is updated to a new version. A description will be given based on 1, 2, and 5. FIG. 5 shows the management server 2 according to this embodiment.
3 is a flowchart showing the flow of the processing of FIG. In this embodiment, for example, a case will be described in which the client 3 issues an update request for version 2 of the atypical information B already stored in the magnetic disk device 10 of the application server 1.

First, the request reception processing section 27 of the management server 2
Receives an update request from the client 3 (S3
1), passing the reception processing result to the database management unit 25,
The data management unit 25 instructs the transmission processing unit 26 to transmit the storage request. The transmission processing unit 26 issues to the application server 1 a storage request for the atypical information B requested to be updated (S32). Application server 1
When receiving the storage request, the reception processing unit 17 notifies the file access unit 15 that the storage request has been received, and the file access unit 15 stores the storage request in the magnetic disk 10. As a result, the atypical information B stored in the magnetic disk device 10 is updated from version 2 to version 3.

Database management unit 25 of management server 2
From the attribute information database 21, the atypical information B is
It is confirmed whether the server side entity notifies / transfers to the client or the client side entity notifies / transfers to the client (S33). If the atypical information is notified / transferred by the server side, the client / user who has a history of extracting the old version (version 1 or 2) of the atypical information B in the past from the access history information database 23 is selected. Search (S3
5).

As a result, it is assumed that the client 4 retrieves the version 1 of the atypical information B in the past. Furthermore, since the notification method is also registered in the attribute information database 21, as the notification method, not the substance of the atypical information but only the notification (update notification only)
In step S36, it is determined whether or not the registration is performed or the automatic transfer is registered.

If registered by the update notification method, the transmission processing unit 26 issues a notification to the client 3 that the atypical information B has been updated (S37).
If registered by the information transfer method, the transmission processing unit 26 issues a request to the application server 1. When the reception processing unit 17 of the application server 1 receives the transmission request, the file access unit 15 causes the magnetic disk 1
Take out the new version 3 of atypical information B from 0,
Transfer to the client 4.

After that, the database management unit 25 of the management server 2 updates the attribute information regarding the updated atypical information in the attribute information database 21 (S39), and updates the update history as the update history in the access history information database 23. , Update client information, update user information, version number and other necessary data are entered (S3
10).

The effect of the file management method in this embodiment will be described. In the file management method according to this embodiment, the server side mainly notifies and transfers the updated atypical information to the client or user who has the atypical information of the old version, and therefore the client or the user retrieves and holds the information. You can forcibly notify or update the atypical information that is being maintained.

In addition, in this embodiment, S in FIG.
As in 35, the management server 2 recognizes the notification or transfer destination by searching the access history information database 23 for the client or the user who has fetched the old version in the past, and thus sets the notification destination or transfer destination in advance. No need.

Further, in the file management method according to the present embodiment, it is possible to select whether the notification / transfer of the non-standard information is performed by the client side or the server side, so that it is possible to select according to the situation of the system. Both can be accommodated. Therefore, a flexible file management system can be configured.

Embodiment 4 In this embodiment, when atypical information having the same keyword as the registered keyword is newly registered / updated, the fact that the new registration / update is performed is automatically notified. Will be described with reference to FIG. Reference numeral 24 in FIG. 1 denotes a keyword registration database provided in the magnetic disk device 20,
Client 3 to the keyword registration database 24
The keyword of the information that 5 wants to refer to is registered. FIG.
3 is a flowchart showing a flow of processing of the management server in this embodiment.

In this embodiment, for example, the client 3 selects "database" as a keyword to be referred to.
"File system" is registered, and client 5
A case where there is a request for new registration of the atypical information C having the keyword “database” will be described. The keywords “database” and “file system” that the client 3 wants to refer to are registered in the keyword registration database 24 in the management server 2.

When the request reception processing unit 27 of the management server 2 receives the registration request for the atypical information C from the client 5 (S41), the reception processing result is stored in the database management unit 25.
Then, the transmission processing unit 26 issues a storage request for the atypical information C to the application server 1 (S43). Upon receiving the storage request, the reception processing unit 17 of the application server 1 causes the file access unit 15 to read the magnetic disk 10
To be stored.

Then, the database management unit 25 of the management server 2 stores the atypical information C in the attribute information database 21.
The attribute information regarding the information is added (S44), and necessary data including the date and time of addition, the additional client information, the additional user information, and the version number are added to the access history information database 23 (S45).

After that, the database management unit 25 searches the attribute information database 21 for the keyword "database" that the registered atypical information C has as attribute information.
And a client that has registered the same keyword is searched (S46). As a result, the client 3 has a “database” as a keyword and is searched. The transmission processing unit 26 issues a registration notice to the client 3 informing that the atypical information C has been newly registered (S47).

Further, not only in the case of new registration, but also when the atypical information C having the keyword "database" is updated (S42), the same operation as in the case of new registration,
The transmission processing unit 26 issues an update notification to the client 3 informing that it has been updated (S48).

The effect of the file management method in this embodiment will be described. Automatic notification of new registration / update when atypical information is newly registered / updated by simply registering a keyword without entering the file name of the atypical information of the field or type that the user or client wants to obtain Can receive. Therefore, it is possible to easily obtain the latest information on the desired field and type.

In this embodiment, a case has been described in which when atypical information having the same keyword as the registered keyword is newly registered / updated, the fact that the new registration / update is automatically notified. Alternatively, the newly registered / updated atypical information can be automatically transmitted. In this case, the content of the atypical information can be obtained without transmitting the information retrieval request.

Embodiment 5 In this embodiment, when one piece of atypical information is extracted, other atypical information related to the extracted atypical information can also be extracted without leakage, and hereinafter, FIG. 1, FIG. 2, and FIG. Will be explained. FIG. 7 is a flow chart showing the flow of processing of the management server of this embodiment. In this embodiment, for example, a case will be described in which the client 3 issues a retrieval request for version 5 of the non-standard information D.

When the request reception processing unit 27 of the management server 2 receives the request for taking out the atypical information D from the client 3 (S51), the reception processing result is passed to the database management unit 25, and the database management unit 25 receives the attribute. The information in the information database 21 is searched for the storage location of the atypical information D, and the transmission processing unit 26 is instructed to notify that the extraction request has been issued. The transmission processing unit 26 notifies the application server 1 that there has been a request from the client 3 to extract the atypical information C (S52).

Reception processing unit 1 of application server 1
When receiving the notification that the extraction request is issued from the transmission processing unit 26, the file access unit 15 extracts the atypical information C from the magnetic disk 10 and the transmission processing unit 16 transmits it to the client 3. Then, the database management unit 25 puts necessary data such as update date and time, update client information, update user information, and version number into the access history information database 23 as update history (S53).

Next, other atypical information related to the atypical information D is searched from the information in the attribute information database 21 (S54). As a result, it is assumed that the atypical information X and the atypical information Y are retrieved. The transmission processing unit 26 uses the client 3
To the atypical information X and the atypical information Y as information related to the retrieved atypical information D (S5).
5).

The effect of the file management method in this embodiment will be described. In the file management method according to the present embodiment, when one piece of non-stereotyped information is extracted, other non-stereotyped information related to the extracted non-stereotyped information can be extracted without being leaked. For example, when a document file and a drawing file in which a drawing corresponding to this document file is stored exist as the atypical information, when the document file is taken out, a notification of the drawing file is received as the associated atypical information. be able to.

Embodiment 6 FIG. The file management method according to this embodiment is to register newly registered atypical information in association with already registered atypical information, and will be described below with reference to FIGS. 1, 2, and 8. FIG.
3 is a flowchart showing the flow of processing of the management server 2 of this embodiment. In this embodiment, for example, the case where the client 3 newly registers the atypical information E and "database" and "file system" are added as attribute information keywords of the atypical information E will be described.

When the request reception processing unit 27 of the management server 2 receives a new registration request for the atypical information E from the client 3 (S61), the reception processing result is stored in the database management unit 2 as a result.
5, the database management unit 25 searches the attribute information database 21 for atypical information with matching keywords (S62). As a result, it is assumed that the atypical information H (version 2) and the atypical information I (version 3) are retrieved.

The transmission processing unit 26 notifies the client 3 of the search result and registers it as the next version (version 3) of the atypical information H that has already been registered, or the next version (version of the atypical information I). Inquiry is made as to whether to register as 4) or to newly register (S63).

Judgment is made from the response from the client 3 (S64), and if the client 3 selects new registration, the database management unit 25 informs the atypical information E.
Is newly registered as version 1 and the attribute information database 21 is updated (S65). Also, the client 3
When the person who registers as the next version of the atypical information I is selected, the database management unit 25 updates the attribute information database 21 with the atypical information E as version 4 of the atypical information I (S66).

Thereafter, the transmission processing unit 26 issues a storage request for the atypical information E to the application server 1 (S6).
7). The reception processing unit 17 of the application server 1
When the storage request is received, the file access unit 15 stores the atypical information E on the magnetic disk 10. The database management unit 25 puts the registration date and time, the registered client information, the registered user information, the version number, etc. in the access history information database 23 as the registration history (S6).
8).

The effect of the file management method in this embodiment will be described. The file management method in this embodiment can associate newly registered atypical information with previously stored atypical information. Therefore,
For example, the stored atypical information can be registered as the next version of the previously stored atypical information. Further, by relating the same type of atypical information to each other, management of atypical information becomes easy.

Embodiment 7 FIG. The file management method in this embodiment periodically checks the free space or access load of the disk and dynamically moves the atypical information, which will be described below with reference to FIGS.
9 and 10 are configuration diagrams of the file management system in this embodiment. This file management system
Multiple application servers 1A on the network,
1B exists, and there are a plurality of magnetic disk devices 10A and 10B.
The atypical information 11A and 11B are distributed and placed in the.

First, a file management method for distributing the load on the magnetic disk according to the free area of the magnetic disk will be described with reference to FIGS. 9 and 10. When storing the atypical information in the application servers 1A and 1B, necessary information is registered in the attribute information database 21 (S71). The information to be registered includes an atypical information name, a storage location of the atypical information, a version number of the atypical information, a data size of negative information, and the like. The management server 2 regularly monitors the storage location and the data size information of the atypical information registered in the attribute information database 21 (S7).
2). From the monitoring result of S72, the magnetic disk device 10
The condition of the free areas A and 10B is determined (S72). When the free space of the magnetic disk device 10A is small, the atypical information 12A having a large data size held by the magnetic disk device 10A is moved to the magnetic disk device 10B having a large free space to distribute the load on the disk. Measure (S74).

Next, a file management method for distributing the load on the magnetic disk according to the access frequency of each atypical information will be described with reference to FIGS. Access history information database 2 when accessing atypical information
The information required for 1 is registered (S81). The information to be registered includes access date and time, access processing content, information indicating the client that has accessed, the name of the atypical information that has been accessed, the version number of the accessed atypical information, and the like. The management server 2 regularly monitors the access date and time registered in the access history information database 23 and the atypical information name that is the access target (S82). S8
From the monitoring result of 2, check the access frequency of each atypical information, check the access status of the entire server,
The load on the application servers 1A and 1B is determined (S83). Then, when the application server 1A has a high load, the atypical information 12A having a high access frequency in the atypical information group 11A held by the application server 1A is copied to the application server 1B having a low load, Atypical information 12A is mirrored between two servers to balance access load (S
84).

Further, the management server 2 determines from the version management database 22 that the atypical information group 11A held by the application server 1A, which has a heavy load, has a new version of atypical information that is expected to be accessed more frequently. 13A is an application server 1 with a low load
Copy to B, atypical information 13A is mirrored, and access load is distributed. The load of the access can be distributed by not only copying the atypical information having a high access frequency from the application server 1A having a high load to the application server 1B having a low load, but also moving it.

The effect of the file management method in this embodiment will be described. At this time, since the attribute information and version information of the atypical information is managed in the database, the client side should be aware of it even if the atypical information is copied and mirrored or moved. You can continue to use without. The atypical information that has been copied and placed in two places can be treated as one atypical information because the two storage locations are managed by the attribute information database. That is, the atypical information placed on the application server 1A and the application server 1B can be associated with each other.

Even if the client requests the update of the mirrored atypical information, since the atypical information is under version management, the atypical information before and after updating should be treated as separate files. You can Since the atypical information that is mirrored does not change itself,
Two types of atypical information do not differ between the two. Also, by periodically checking the access history database, it is possible to automatically cancel mirroring when the access load of atypical information being mirrored becomes low.

According to the file management method of this embodiment, the management server 2 periodically checks the access history database 23 even if the free space of the disk or the access load changes.
Atypical information can be moved dynamically. In the file management method according to this embodiment, the management server 2 performs the load balancing process using the attribute information database 21 or the access history information database 23, so that the operator does not need to be aware of the configuration of the storage device.

Embodiment 8 FIG. The file management method according to the present embodiment stores atypical information having a small access load in a storage device that is relatively slow but inexpensive, and will be described below with reference to FIG. In the figure, 3
Reference numerals 0 and 40 denote tapes and magneto-optical disks provided in the application server 1, and the application server 1 stores atypical information in the tape 30 and the magneto-optical disk 40. The other configuration is the same as that of the above embodiment, and the description is omitted.

In addition to the online magnetic disk device 10, this system is not limited to the tape 30 and the magneto-optical disk 40.
It is equipped with a storage device such as. The management server 2
Based on the access history information database 23 of atypical information, the access status of atypical information is regularly checked. Atypical information that has not been accessed is moved to a relatively low-speed, large-capacity, inexpensive storage device that can be accessed online (for example, the tape 30 or the magneto-optical disk 40) and saved.

If the client requests access to the saved atypical information, the saved atypical information is also managed by the attribute information database 23 and can be accessed online. You can access without being aware of it. Further, when the number of access requests for the saved atypical information increases, the atypical information can be transferred to a high-speed storage device.

In the file management method according to this embodiment, the non-standard information having a small access request is stored in the tape 30 or the magneto-optical disk 40 having a relatively low speed so that the capacity of the high speed magnetic disk is frequently accessed. Can be used for atypical information. Therefore, the storage device can be used economically.

In the file management method of this embodiment, the information stored in the relatively low-speed storage medium is atypical information with few access requests, and therefore has little effect on access time.

In the description of this embodiment, the case where the number of clients is three has been described. However, a plurality of clients may be provided, and in this case, the same function as described above is performed. Furthermore, in the description of the embodiment, one or two application servers and magnetic disks are used, but the same can be applied to a plurality of application servers and magnetic disks.

[0105]

Since the present invention is constructed as described above, it has the following effects. According to the file management method of the present invention, a reference request step for requesting a reference to a file held in a server, a determination step for determining a request unit of the reference request, and a type of request unit determined in the determination step are provided. Retrieval step for retrieving the version of the file retrieved in the past, a comparison step for comparing the file version retained in the server with the retrieved file version, and the retrieved file version in the comparison step When the version of the file held in the server is newer than that of the file, there is a transmitting step of transmitting the reference information according to the request unit determined in the determining step. Flexible file reference according to the request unit of Can.

The file management method in the second invention is
The request unit is a client unit or a user unit. In the search step, if the determination result in the determination step is a client unit request, the version of the file extracted in the past by the client making the reference request. When the determination result in the determination step is a request for each user, the version of the file retrieved in the past by the user who issued the reference request is searched. , Flexible file browsing can be done.

The file management method in the third invention is as follows:
When the file held in the server is updated, a notification method setting step of setting the notification of the update of the file or setting of the updated file in response to the request from the client, and the notification or Depending on the subject setting step for setting changeable whether the transfer is performed by the client side or the server side, the subject determining step for determining the setting content in the subject setting step, and the determination result in the subject determining step A search step of searching for a client to whom the file has been updated or a transfer destination of the updated file, and a notification that the file has been updated to the client searched in the search step Alternatively, a transmission step for transferring the updated file Since having, it is possible to perform update processing of the flexible file according to the situation of a file management system that the client-side entity or server-side entity.

The file management method in the fourth invention is
In the search step, if the determination result in the subject determination step is the client side, the client that made the notification or transfer setting request in the notification method setting step is searched for the file for which the update request is made, and If the discrimination result in the subject discriminating step is the server side principal, the client that retrieved the old version of the file for which the update request was made in the past is searched. It is possible to appropriately search the notification destination that the file has been updated or the transfer destination of the updated file.

The file management method in the fifth invention is
The server holds the file in response to the keyword registration step of registering the keyword corresponding to the information desired by the client, the holding request step of requesting the server to hold the file, and the holding request in the holding request step. A holding step, a keyword recognition step for recognizing a keyword attached to a file for which a holding request is made in the holding request step, and a keyword recognized in the keyword recognition step among the keywords registered in the registration step. Since it has a search step of searching for the corresponding keyword, and a holding notification step of notifying that the holding step has been executed to the client that has requested acquisition of information corresponding to the keyword searched in the searching step, By registering a keyword corresponding to the information you wish to hand, it can be obtained without leaking the information that the client wishes to obtain.

A file management method according to the sixth invention is as follows:
In the search step, the same keyword as the keyword recognized in the keyword recognition step is searched from the keywords registered in the registration step, so that the search can be easily performed.

The file management method in the seventh invention is
A retrieval request step in which the client requests retrieval of the file held in the server, a keyword recognition step of recognizing a keyword attached to the file requested in the retrieval request step, and a plurality of files retained in the server From the above, there is a search step of searching for a file corresponding to the keyword recognized in the keyword recognition step, and a search result notification step of notifying the client searched for the file searched in the search step. , The client can know without leaking other files related to the file requested to be retrieved.

The file management method in the eighth invention is
Keywords are attached to the plurality of files stored in the server, and are the same as the keywords recognized in the keyword recognition step from the keywords attached to the plurality of files stored in the server in the search step. Since the keyword is searched for, the search can be easily performed.

A file management method according to the ninth invention is
A holding request step for requesting holding of the file in the server and a plurality of files held in the server are searched for a file corresponding to the keyword attached to the file requested in the holding request step. A searching step; a selecting step of selecting whether to hold the file requested to be held in the holding request step in the server in association with the file searched in the searching step; and a selecting step in the selecting step. According to the selection result, the holding step for holding the file for which the holding request is made is held in the server. Therefore, the file for which the holding request is made can be easily associated with the file already held in the server.

In the file management method according to the tenth aspect of the invention, since the client makes the holding request in the holding request step and the client makes the selection in the selecting step, the client makes a holding request in accordance with the request. The association allows the file to be retained on the server.

A file management method according to the eleventh aspect of the invention is a file management method for managing access to a plurality of files held by a server, wherein information on the plurality of files stored in a storage device related to the server. A file stored in the storage device is stored in the storage device in accordance with a monitoring step for monitoring the amount, a load determination step for determining the load of the storage device from the monitoring result in the monitoring step, and a determination result in the load determination step. And a storage step of storing the storage device in another storage device, the load of the storage device can be distributed according to the situation.

In the file management method according to the twelfth invention, the information amount of the plurality of files in the monitoring step is monitored in the first registration area in which the information amounts of the plurality of files are registered. Since it is performed by, it is not necessary to confirm the information in other registration areas, and the burden of monitoring is lightened.

A file management method according to a thirteenth invention is a file management method for managing access of a client to a plurality of files held in a server, wherein the client manages files stored in a storage device related to the server. A monitoring step for monitoring the access status of the server, a load determining step for determining the load on the server from the monitoring result in the monitoring step, and a file stored in the storage device according to the determination result in the load determining step. Since it has a storage step of storing in a storage device different from the device, the load of the server can be distributed according to the situation.

In the file management method of the fourteenth invention, the access status monitoring in the monitoring step is
Since it is performed by monitoring the information in the second registration area in which the time when the client has accessed the file stored in the storage device is registered, it is not necessary to check the information in other registration areas. The burden of monitoring is reduced.

A file management apparatus according to the fifteenth invention is a file management apparatus for managing access to a plurality of files held by a server, and a storage means for storing the plurality of files held by the server, A first registration area in which information amounts of a plurality of files stored in a storage unit are registered, and an information amount of a plurality of files registered in the first registration area are monitored, and the above Since the storage means has a management means for storing the file stored in the storage means in a storage means different from the storage means, the load of the storage device can be distributed according to the situation.

A file management device according to the sixteenth invention is a file management device for managing access of a client to a plurality of files stored in a server, and a storage means for storing the plurality of files stored in the server. And monitoring the second registration area in which the time when the client has accessed the plurality of files stored in the storage means is registered, and the time registered in the second registration area, and depending on the time. Since it has a management means for storing the file stored in the storage means in a storage means different from the storage means, the load of the server can be distributed according to the situation.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a file management system according to first to sixth embodiments.

FIG. 2 is an internal configuration diagram of an application server 1, a management server 2 and a client 3.

FIG. 3 is a flowchart showing an operation of the management server 2 according to the first embodiment.

[Fig. 4] Automatic notification from the client to the management server 2 /
It is a flowchart which shows operation | movement when an automatic update request is received.

FIG. 5 is a flowchart showing an operation when the management server 2 in Embodiments 2 and 3 receives an update request.

FIG. 6 is a flowchart showing the operation of the management server 2 according to the fourth embodiment.

FIG. 7 is a flowchart showing the operation of the management server 2 in the fifth embodiment.

FIG. 8 is a flowchart showing an operation of the management server 2 according to the sixth embodiment.

FIG. 9 is a configuration diagram of a file management system for performing disk load distribution according to the seventh embodiment.

FIG. 10 is a flowchart showing a file management method for performing load distribution on a disk.

FIG. 11 is a configuration diagram of a file management system for load balancing of servers according to the seventh embodiment.

FIG. 12 is a flowchart showing a file management method for load balancing of servers.

FIG. 13 is a configuration diagram of a file management system in the eighth embodiment.

FIG. 14 is a configuration diagram of a conventional file management system for balancing the load of resources by a shared file.

FIG. 15 is a configuration diagram of a conventional file management system in which each client manages information on files held by the clients.

FIG. 16 is a configuration diagram of a conventional file management system in which a server manages information of files held by a client.

[Explanation of symbols]

1 application server, 2 management server, 3-5
Client, 6 network, 10 magnetic disk device, 11 atypical information file, 15 file access unit, 16 transmission processing unit, 17 reception processing unit, 20
Magnetic disk device, 21 Attribute information database, 22
Version management database, 23 access history information database, 24 keyword registration database,
25 database management unit, 26 transmission processing unit, 27
Request reception processing unit, 30 tapes, 31 reception unit, 32
Request transmitter, 40 magneto-optical disk. 31

Claims (16)

[Claims] 1. A reference request step for requesting a reference to a file stored in a server, a determination step for determining a request unit of the reference request, and a past step according to the type of request unit determined in the determination step. A search step for searching the version of the retrieved file; a comparison step for comparing the version of the file held in the server with the version of the searched file; and A file management method comprising a step of transmitting reference information according to the request unit determined in the determination step when the version of the file held in the server is newer. 2. The request unit is a client unit or a user unit, and in the search step, when the determination result in the determination step is a client unit request, the client that has issued the reference request has a past request. Search the version of the retrieved file,
The file management method according to claim 1, wherein when the determination result in the determination step is a request for each user, the version of the file extracted in the past by the user who has issued the reference request is searched. 3. A notification method setting step of setting a notification that the file has been updated when the file held in the server has been updated or setting the transfer of the updated file in response to a request from the client. And, the above notification or transfer is performed by the client side,
The file is updated according to the subject setting step of setting whether or not to be performed by the server side subject, the subject determining step of determining the setting content in the subject setting step, and the determination result of the subject determining step. A search step of searching for a client as a notification destination or a transfer destination of the updated file, and a notification that the file has been updated or a transfer of the updated file to the client searched in the search step. A file management method having a transmitting step of performing. 4. The client that has made the notification or transfer setting request in the notification method setting step for the file for which the update request is made if the determination result in the subject determination step is the client side in the search step. 4. The file management method according to claim 3, further comprising: searching for a client that has fetched an old version of the file for which the update request was made in the past if the determination result in the subject determination step is a server-side subject. . 5. A server according to a keyword registration step of registering a keyword corresponding to information desired by a client, a retention request step of requesting retention of a file to a server, and a retention request in the retention request step. A holding step for holding the file, a keyword recognition step for recognizing a keyword attached to the file for which a holding request is made in the holding request step, and a keyword recognizing step from the keywords registered in the registering step. A search step of searching for a keyword corresponding to the recognized keyword, and a holding notification step of notifying that the holding step has been executed to a client who has requested acquisition of information corresponding to the keyword searched in the searching step. File management method characterized in that it comprises a. 6. The file management method according to claim 5, wherein in the searching step, the same keyword as the keyword recognized in the keyword recognizing step is searched from the keywords registered in the registering step. . 7. A retrieval request step in which a client requests retrieval of a file retained in a server, a keyword recognition step of recognizing a keyword attached to the file requested in the retrieval request step, and retained in the server. A retrieval step of retrieving a file corresponding to the keyword recognized in the keyword recognition step from the plurality of retrieved files, and a retrieval result notification for notifying the file retrieved in the retrieval step to the client requesting the retrieval. A file management method comprising: 8. A keyword is attached to the plurality of files stored in the server, and the search step is performed in the keyword recognition step from the keywords attached to the plurality of files stored in the server. The file management method according to claim 7, wherein the same keyword as the retrieved keyword is searched. 9. A holding request step for requesting holding of a file in a server, and a plurality of files held in the server,
A search step for searching a file corresponding to the keyword attached to the file requested in the holding request step, and a search step for holding the file for which the holding request is made in the holding request step in the server And a holding step of holding the file for which the holding request is made in the server according to the selection result in the selecting step. How to manage files. 10. The file management method according to claim 9, wherein the holding request in the holding request step is made by a client, and the selection in the selecting step is made by the client. 11. A file management method for managing access to a plurality of files held by a server, the monitoring step of monitoring the information amount of the plurality of files stored in a storage device related to the server, The load determination step of determining the load of the storage device from the monitoring result in the monitoring step, and the file stored in the storage device is stored in a storage device different from the storage device according to the determination result in the load determination step. And a storing step for storing the file. 12. The information amount of the plurality of files in the monitoring step is monitored by monitoring information in a first registration area in which the information amounts of the plurality of files are registered. The file management method according to claim 11. 13. A file management method for managing access of a client to a plurality of files held in a server, the monitoring step of monitoring an access status of the client to a file stored in a storage device related to the server. And a load determination step of determining the load of the server from the monitoring result in the monitoring step, and a file stored in the storage device in a storage device different from the storage device according to the determination result in the load determination step. And a storing step of storing the file. 14. The monitoring of the access status in the monitoring step is performed by monitoring information in a second registration area in which a time when the client has accessed a file stored in the storage device is registered. 14. The file management method according to claim 13, wherein: 15. A file management device for managing access to a plurality of files stored in a server, the storage device storing a plurality of files stored in the server, and a plurality of storage units stored in the storage unit. The first registration area in which the information amount of the file is registered, and the information amounts of the plurality of files registered in the first registration area are monitored, and the files stored in the storage means are stored in accordance with the information amount of the file. A file management device comprising: management means for storing in a storage means different from the storage means. 16. A file management device for managing access of a client to a plurality of files stored in a server, the storage device storing the plurality of files stored in the server, and the storage device stored in the storage unit. A second registration area in which the time when the client has accessed a plurality of files is registered, and the time registered in the second registration area is monitored and stored in the storage means according to the time. A file management device comprising: a management unit that stores a file in a storage unit different from the storage unit.