JPH0713829A - Data base backup system - Google Patents

Abstract

PURPOSE:To freely access a data base even during backup copying operation by recording data base access in the backup copying operation and reflecting it on a backup file. CONSTITUTION:A copying means 4 includes a temporary storage means 6 which temporarily stores part of information recorded in a lst large-sized memory 1, a file generation part 7 which copies the information stored in this temporary storage means 6 to a 2nd large-sized memory 2, and a data base copy part 9. Further, the system is equipped with an access log means 8 which records the position and contents of writing to the 1st large-sized memory 1 by an access means 5. Then the file generation part 7, when copying the information stored in the temporary storage means 6 to the 2nd large-sized memory 2m judges whether writing regarding the information to be transferred is done after the information is stored in the temporary storage means 6 by referring to the access log means 8 and then writes information indicating the writing in the 2nd large-sized memory 2 when the writing is done.

Description

Detailed Description of the Invention

[0001]

The present invention is used in an electronic computer.
The present invention relates to an improvement of a backup method in which large-scale data stored in a memory as a database is duplicated and stored in another backup memory.

[0002]

2. Description of the Related Art In order not to lose the database recorded in a large memory, a second large memory having the same capacity as that of the first large memory in common use is prepared as a backup and A backup method in which a database is duplicated in the second large memory is widely used. In such a conventional method, when the database recorded in the first large-sized memory for regular use is copied to the second large-sized memory for backup, new writing to the database is temporarily prohibited. The write protection is released after the copy to the second large memory is completed.

When writing cannot be prohibited, writing (or access of the same contents) is executed in parallel for the first large memory and the second large memory.

A technique for recording the access history to a regular database is disclosed in Japanese Patent Laid-Open No. 62-50938, but this is for restoring the database when it is destroyed. Therefore, the present invention is a technology whose purpose is different from that of the present invention.

[0005]

In such a conventional example method, the user of the database can access the database while the step of copying the information in the first large memory to the second large memory is executed. There is a drawback that it cannot be used. On the other hand, in a configuration in which two large memories are accessed in parallel, the device configuration becomes complicated, the access time becomes long, and the information in the two large memories does not differ for some reason. There are drawbacks such as the need for management.

The present invention improves on this by allowing the database user to access the database even during the production of the replica, without increasing the access time.
An object of the present invention is to provide a backup method that does not require management for maintaining the identity of two memory contents.

[0007]

According to the present invention, there is provided a first large memory in which a database is recorded, a second large memory for backup in which data equivalent to the database is recorded, and the first large memory. In a database backup system comprising a duplication means for duplicating a database recorded in a large-sized memory in the second large-sized memory and an access means for writing and / or reading in the first large-sized memory The duplication means temporarily stores at least a part of the information recorded in the first large-sized memory, and the information stored in the temporary storage means is transferred to the second large-sized memory. An access log unit for recording the position and contents of the write executed by the access unit to the first large-sized memory, When the information stored in the temporary storage means is transferred to the second large-sized memory, the file generation section writes the information to be transferred after the information is stored in the temporary storage means and then writes the information. It is characterized in that it includes means for referring to the access log means to determine whether or not there has been, and for writing, when there is writing, the information for executing the writing to the second large-sized memory.

The capacity of the first large memory and the capacity of the second large memory are substantially equal to each other, the capacity of the temporary storage means is smaller than the capacity of the first large memory, and the copying means is The temporary storage means is provided with a means for duplicating each portion according to the capacity of the temporary storage means, and the writing and reading speeds of the temporary storage means are higher than the writing and reading speeds of the first or second large-sized memory. Is desirable.

[0009]

According to the method of the present invention, when performing duplication,
The information recorded in the first large-sized memory is temporarily transferred to the temporary storage means, and the information stored in this temporary storage means is further transferred to the second large-sized memory. It is desirable to use the temporary storage means for writing and reading operations at a speed higher than that of the large-sized memory. Also, the storage capacity of the temporary storage means is smaller than that of the large-sized memory. It is desirable to repeatedly perform the operation of transferring to the above and transferring this for each part.

The system of the present invention does not prohibit access to the regular large memory (first large memory) even during execution of copy creation. Therefore, it is possible that new writing occurs in the first large-sized memory for the data once transferred to the temporary storage means. In order to remedy this, the position and contents of the writing executed in the first large-sized memory are recorded in the access log means, and this access log is recorded when the transfer is performed in the second large-sized memory. With reference to the contents of the means, when there is a new writing in the related portion, the writing is executed in the second large-sized memory in the form of executing the new writing.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

In the embodiment of the present invention, a first large memory 1 in which a database is recorded and a second large memory 2 for backup in which data equivalent to this database is recorded.
And a central processing unit 3, and the central processing unit 3 is
Copying means 4 for copying the database recorded in the first large-sized memory 1 to the second large-sized memory 2, and access means 5 for writing and / or reading the first large-sized memory 1.
Further, as a feature of the present invention, the duplication unit 4 is provided.
Is a temporary storage means 6 for temporarily storing at least a part of the information recorded in the first large-sized memory 1, and a file for transferring the information stored in this temporary storage means 6 to the second large-sized memory 2. The file generation unit 7 includes a generation unit 7 and a database copy unit 9, and includes an access log unit 8 for recording the position and contents of writing executed by the access unit 5 to the first large-sized memory 1. In the case of transferring the information stored in the temporary storage means 6 to the second large-sized memory 2, whether the information to be transferred has been written in the temporary storage means 6 and then the information was written. It includes means for referring to the access log means 8 to determine whether or not there is writing, and writing the written information to the second large-sized memory 2.

The capacity of the first large-sized memory 1 and the capacity of the second large-sized memory 2 are substantially equal to each other, the capacity of the temporary storage means 6 is smaller than the capacity of the first large-sized memory 1, and the copying means 4 is temporary. The temporary storage means 6 has a writing / reading speed for writing / reading to / from the first large-sized memory 1 or the second large-sized memory 2 by providing a means for making a copy for each part according to the capacity of the storing means 6. It is done faster than speed.

A plurality of lines are connected to the central processing unit 3 via a line interface 11, and a console 13 having a storage device 12 and a CRT 13a and a keyboard 13b is further connected.

Next, the operation of the embodiment of the present invention thus constructed will be described with reference to the drawings. FIG. 2 is a flow chart showing the operation flow of the embodiment of the present invention.

At the start of the backup of the database recorded in the first large-sized memory 1, first, the database copy section 9 of the duplicating means 4 is activated to store the database of the first large-sized memory 1 in the temporary storage means 6. make a copy. At the same time, the access log unit 8a is activated, and the information on the access to the database during the copying of the database of the first large-sized memory 1 is obtained by the normal database access processing. The access log unit 8a uses the information obtained from this database access process as the access log 8a.
Record in b. When the copying of the database in the first large memory 1 by the database copying unit 9 is completed, the operation of the access log unit 8a is also completed. After that, the file generation unit 7 starts execution, acquires the update data of the database performed during the copying of the database of the first large-sized memory 1 from the access log 8b, and updates the temporary storage unit 6, A backup file is created in the second large memory 2.

[0017]

As described above, according to the present invention, since the database access during the backup copy can be recorded and reflected in the backup file, the database user can freely access the database even during the backup copy. In addition, there is an effect that the disk access time can be significantly shortened when compared with the method of simultaneously accessing two files.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of operations of the embodiment of the present invention.

[Explanation of symbols]

 1 First Large Memory 2 Second Large Memory 3 Central Processing Unit 4 Duplicating Means 5 Access Means 6 Temporary Storage Means 7 File Generating Unit 8 Access Log Means 8a Access Log Means 8b Access Log 9 Database Copy Means 11 Line Interface 12 storage device 13 console 13a CRT 13b keyboard

Claims (3)

[Claims] 1. A first large memory in which a database is recorded, a second large memory for backup in which data equivalent to this database is recorded, and a database recorded in the first large memory. In a database backup system comprising: a duplication unit that duplicates the data in the second large memory, and an access unit that writes and / or reads the first large memory. A temporary storage means for temporarily storing at least a part of the information recorded in the one large memory; and a file generation section for transferring the information stored in the temporary storage means to the second large memory, An access log unit for recording the position and contents of the writing executed by the access unit to the first large-sized memory; When transferring the information stored in the temporary storage means to the second large-sized memory, the access is made as to whether or not the information to be transferred has been written after the storage in the temporary storage means. A database backup system characterized in that it includes means for referring to the log means and for writing the written information to the second large-sized memory when there is writing. 2. The capacity of the first large-sized memory and the capacity of the second large-sized memory are substantially equal to each other, the capacity of the temporary storage means is smaller than the capacity of the first large-sized memory, and the duplication means. The database according to claim 1, further comprising means for copying each part according to the capacity of the temporary storage means.
Backup method. 3. The database backup method according to claim 1, wherein the writing and reading speeds of the temporary storage means are higher than the writing and reading speeds of the first or second large-sized memory.