JP2002140314A - System and method for copying data and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce deterioration in performance accompanying memory copying by shortening the time when a memory area as a copy source is inhibited from being written in. SOLUTION: If a request to write a copy source memory is generated before data of a copy source area in a copy source memory are copied to a copy destination memory, an area wherein the write request is generated is recognized and when the recognized area is a copy-uncompleted area, the data in the area are copied to the copy destination memory preferentially, and the copy- completed area in the copy source memory is recognized and the recognized copy-completed area in the copy is deleted from the copy source area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data copy system, a data copy method, and a storage medium for copying data on a memory between the same computer or different computers.

[0002]

[0003]

2. Description of the Related Art Conventionally, when data on a memory is copied to another memory area on the same computer or a different computer, the data on the memory at the copy source is not updated during the copying. There is a need. For this reason, the entire memory area of the copy source is locked and write protected until the copy is completed.

[0004]

As described above, while data on the memory is being copied, it is necessary to prohibit writing to the entire area so that the data on the memory is not updated. The larger the size of the memory area to be written, the longer the time during which writing cannot be performed. This time is even longer in the case of remote copy in which data on the memory is copied to a memory area on another computer.

[0005] Therefore, when a process of frequently updating and copying a large-sized memory area is repeatedly performed, there is a problem that the memory copy time becomes a bottleneck and the performance cannot be improved.

As described above, conventionally, when data in a memory is copied to another memory area, writing has been conventionally prohibited until copying of the entire memory area is completed.
When processing such as repeating update and copy for a large memory area was performed, the copy time became a bottleneck and performance did not improve.

[0007] It is an object of the present invention to reduce the performance degradation caused by memory copy by shortening the write prohibition time for the memory area of the copy source even when copying data in a large-sized memory. A data copy system, a data copy method, and a storage medium are provided.

[0008]

According to a first aspect of the present invention, there is provided a copy means for copying data in a copy source area on a copy source memory to a copy destination memory, and a copy by the copy means. When a write request to the copy source memory is issued before the operation is completed, a recognizing means for recognizing the area where the write request is generated, and when the area where the write request recognized by the recognizing means is not an already copied area Priority copying means for copying the data in the area to the copy destination memory prior to the copy operation by the copying means; copied area recognition means for recognizing an already copied area in the copy source memory; The area already copied in the copy source memory recognized by the recognition means is A data copy system characterized by comprising: means for external.

According to a second aspect of the present invention, when a write request to the copy source memory occurs before the operation of copying the data in the copy source area on the copy source memory to the copy destination memory is completed, the write request is generated. When the area where the recognized write request is generated is not the already copied area, the data in the area is copied to the copy destination memory in preference to the copy operation, and the data in the copy source memory is copied. A data copy method characterized by recognizing an area and excluding the recognized area in the copy source memory from the copy source area.

According to a third aspect of the present invention, in the data copy method of the second aspect, the copy operation is periodically repeated.

The invention according to claim 4 is applied to a computer system for copying data in a copy source area on a copy source memory to a copy destination memory, and executes a predetermined operation according to a program read from an external storage medium. The computer-readable storage medium used for: when a write request to the copy source memory occurs before the operation of copying the data in the copy source area on the copy source memory to the copy destination memory is completed, Recognizing the area where the write request has occurred, and copying the data of the area to the copy destination memory prior to the copy operation when the area where the write request has been recognized is not the area already copied And recognizes the already copied area in the copy source memory. Computer-readable storage medium storing a program for already executing a step of excluding the copied region from the copy source area, the in the copy source memory which identifies a.

According to the above-described inventions, when copying is started, data on the copy source memory is copied, and a write request is issued to an area that has already been copied before the copy operation is completed. Is permitted, and if there is a write request for an area that has not yet been copied, that area is preferentially copied, and that copy of the area is considered completed.
Since the re-copying of those pages is suppressed, it is possible to minimize the write prohibition time during execution of the copy and prevent performance degradation.

[0013]

FIG. 1 shows a system to which a data copy system, a data copy method, and a storage medium of the present invention are applied. The system includes an Internet, a network using a public telephone line, a private network, and the like. A primary computer 20 on the network 10;
The configuration is such that a backup computer 30 is connected. Further, the primary computer 20 is equipped with hardware or software for executing a copy method described later. Of course, when such hardware or software is not provided, a method described later can be implemented by installing a program stored in the disk 40 via the network 10 or directly.

Here, whether the copy source and the copy destination are the same or different is not essentially different in the copy operation itself, but the data operation is performed on a memory such as a database of the primary computer 20. When copying data of one area to another area, data of a specific area on a memory such as a database of the primary computer 20 may be copied to a specific area on a memory such as a database of the backup computer 30.

FIG. 2A shows the former example, in which data in one area 21A on the database 21 of the primary computer 20 is copied to another area 21B on the database 21 of the primary computer 20 as well. Is shown.

FIG. 2B shows the latter example, in which the data of one area 21 A on the database 21 of the primary computer 20 is transferred to the backup computer 3.
0 shows a case where the data is copied to the area 31A on the database 31.

The copy operation includes a one-time copy operation, a plurality of irregular copy operations, and a periodic repetitive copy, but there is no essential difference in the copy operation itself.

Each of the embodiments described below has a configuration according to the difference in the copy destination and the frequency of the copy operation under the above-described common data copy method.

(First Embodiment) FIG. 3 shows a copying method and system according to a first embodiment of the present invention.

In the present embodiment, write protection is applied to the entire memory area of the copy source before copying is started, and when a write request occurs during copying, the exception handler as the write request recognition means 2 is started. Keep it. The exception handler recognizes the page on which the write request has occurred from the address where the write exception has occurred.

The flow until all data in the memory area A is copied to the memory area B will be described below with reference to FIG.

First, as shown in FIG. 3A, the data in the memory area A is sequentially copied to the memory area B by the memory copy means 1 in page units. This process is continued until all the write-protected pages in the memory area A are copied to the memory area B. Pages that are not write protected are not copied. The memory copy unit 1 removes write protection of the copied page.

In FIG. 3B, following FIG. 3A, even while data is being copied by the memory copying means 1, writing to a page for which copying has already been completed is permitted as it is.

In FIG. 3C, following FIG. 3B, if there is a write request for a page that has not been copied before the data copy by the memory copy unit 1 is completed, the write request is made. After recognizing the memory copy unit 1, the recognition unit 2 activates the priority memory copy unit 3 to copy the page first. After the copy is completed, the write protection of the page is removed, writing is permitted, and the process of the memory copy unit 1 is restarted.

In FIG. 3D, following FIG. 3C, the memory copy unit 1 copies the remaining pages that have not been copied. Since the page that has already been copied according to FIG. 3C has been write-protected by the write request recognition unit 2, the memory copy unit 1 does not copy this page again.

In the present embodiment, the processing can be reversed so that the data in the memory area B is copied to the memory area A in the same manner.

Next, normal copy processing in the first embodiment will be described with reference to FIG. In FIG. 4, in step S1, write protection is applied to the memory area of the copy source.

In step S2, an exception handler, which is a write request recognition means 2 for performing a page fault process when writing is performed on a page for which write protection has been set, is set.

In step S3, the data in the memory area of the copy source is sequentially copied to the memory area of the copy destination by the memory copy means 1.

In step S4, it is determined in step S3 whether the page to be copied next is write-protected.

In step S5, if the page in step S4 is write-protected, the memory copy means 1 copies that page and removes the write protection.

In step S6, it is determined whether copying of all pages has been completed.

In step S7, if all the pages have been copied in step S6, the copying is completed, and if there are remaining pages that have not been copied, the processing in step S3 is repeated.

Next, processing in the case where an exception has occurred in the first embodiment will be described with reference to FIG. FIG.
In step S8, the memory copy unit 1 detects that a write exception has occurred during the memory copy.

In step S9, the write request recognition means 2 checks the page where the exception has occurred.

In step S10, it is determined whether the exception has occurred in the page in the memory area being copied.

In step S11, if the page in step S10 is in the memory area being copied, this page is copied by the preferential memory copy means 3 and the write protection is removed.

In step S12, the exception process has been completed.

As described above, according to the present embodiment, when copying all the data in the memory area A to the memory area B, when the copy is started, the data in the copy source memory is copied. If there is a write request for an area that has already been copied before it is completed, the request is permitted.If there is a write request for an area that has not been copied, that area is given priority. Since the copy is completed and the copy of the area is completed, the re-copying of those pages is suppressed, so that the write-protection time during the copy execution can be minimized, and the performance can be prevented from deteriorating.

(Second Embodiment) FIG. 6 shows a copying method and system according to a second embodiment of the present invention.

In this embodiment, before starting copying, write protection is applied to the entire memory area of the copy source, and when a write request occurs during the copy, the exception handler as the write request recognition means 2 is started. Keep it. This exception handler recognizes the page on which the write request has occurred from the address where the write exception has occurred. Copy target page registration means 4 for specifying a page to be copied
Is created.

Hereinafter, a flow until all data in the memory area A is copied to the memory area B in this embodiment will be described with reference to FIG.

In FIG. 6A, the data on the memory area A is sequentially copied to the memory area B by the memory copy means 1 in page units. This process continues until all pages specified by the copy target page registration unit 4 have been copied.

The information of the page copied by the memory copy unit 1 is deleted from the copy target page registration unit 4.

At the start of copying, all pages in the memory area A are registered in the copy target page registration means 4.

In FIG. 6B, when a write request is made to a page whose copying has already been completed before the data copying by the memory copying unit 1 is completed, the writing request recognizing unit 2 immediately returns to the page. Remove write protection from the page and allow writing.

In FIG. 6C, if a write request is made to a page that has not yet been copied before the data copy by the memory copy means 1 is completed, the write request recognition means 2 sets the memory copy means. After interrupting the processing in step 1, the priority memory copy unit 3 is activated to copy the page first, and the information of the page is deleted from the copy target page registration unit 4.

After the copy is completed, the write protection of the page is removed, writing is permitted, and the processing of the memory copying means 1 is restarted.

In FIG. 6D, the memory copy means 1
Copy the remaining pages that have not been copied yet. FIG.
Since the page already copied by (c) has been deleted from the copy target page registration unit 4, the memory copy unit 1 does not copy this page again.

In the present embodiment, the processing can be reversed so that the data in the memory area B is copied to the memory area A in a similar manner.

Next, normal copy processing in the second embodiment will be described with reference to FIG. In step T1, write protection is applied to the memory area of the copy source.

In step T2, an exception handler, which is write request recognition means 2 for performing a page fault process when writing is performed on a page for which write protection has been set, is set.

In step T3, copy target page registration means 4 for designating a page to be copied is created.

In step T4, the page designated by the copy page registering means 4 is copied by the memory copying means 1.

In step T5, the memory copy unit 1
Deletes the information of the copied page from the copy target page registration unit 4.

In step T6, it is determined whether or not copying of all pages has been completed.

In step T7, if all pages have been copied in step T6, the copying is completed, and if there are remaining pages that have not been copied, the process of step T4 is repeated.

Next, processing in the case where an exception has occurred in the second embodiment will be described with reference to FIG. In step T8, the memory copy unit 1 detects the occurrence of the write exception during the memory copy.

In step T9, the write request recognition means 2 checks the page where the exception has occurred.

In step T10, it is determined whether or not the exception has occurred in the page in the memory area being copied.

In step T11, if the page of step T10 is in the memory area being copied, it is determined whether or not the page is registered in the copy object registration means 4.

In step T12, if the page is registered in the page copy target registration unit 4 in step T11, this page is copied by the priority memory copy unit 3,
The information of this page is deleted from the copy target registration unit 4.

In step T13, if the page where the exception has occurred is a page in the memory area being copied, the write protection of this page is removed.

In step T14, the exception process is completed.

As described above, according to this embodiment, when copying all the data in the memory area A to the memory area B, when the copy is started, the data in the copy source memory is copied. If there is a write request for an area that has already been copied before it is completed, the request is permitted.If there is a write request for an area that has not been copied, that area is given priority. Since the copy is completed and the copy of the area is completed, the re-copying of those pages is suppressed, so that the write-protection time during the copy execution can be minimized, and the performance can be prevented from deteriorating.

(Third Embodiment) FIG. 9 shows a copying method and system according to a third embodiment of the present invention.

In the present embodiment, not all data in the copy area is copied, but the pages a,
Only b, c, and d are to be copied.

It should be noted that the updated page is a page whose write protection has been removed by the write request recognition means 2 since the previous copy started, and updated page information is registered in the write page registration means 5.

Before the copy from the memory area A to the memory area B is started, these updated pages are also write-protected again, and the fact that a write request has been made during the copy is notified to the write request recognition means 2. To be recognized.

Further, copy target page registration means 4 for designating a page to be copied is created.

Referring to FIG. 9, pages a, b, c, and d on memory area A updated from the time when the previous copy was started to the time when the current copy was started are stored in memory area B. The flow until copying is described.

In FIG. 9A, the page in the memory area A updated from the time when the previous copy was started to the time when the current copy is started by the memory copy means 1 is shown in FIG.
The data is sequentially copied to the memory area B in page units. This process continues until all pages specified by the copy target page registration unit 4 have been copied.
The page information copied by the memory copy unit 1 is deleted from the copy target page registration unit 4.

At the start of copying, page information registered in the write page registering unit 5 is registered in the copy target registering unit 4.

In FIG. 9B, until the data copy by the memory copy means 1 is completed, there is a write request for a page that has not been updated since the start of the previous copy or for a page that has already been copied. In this case, the write request recognition means 2 immediately removes write protection of the page and permits writing. Also, the information of this page is registered in the write page registration means 5.

In FIG. 9C, if a write request is made to a page that has not been copied before the data copy by the memory copy means 1 is completed, the write request recognition means 2 sets the memory copy means. After interrupting the processing in step 1, the priority memory copy unit 3 is activated to copy the page first, and the information of the page is deleted from the copy target page registration unit 4.

After the copy is completed, the write protection of the page is removed, writing is permitted, and the processing of the memory copying means 1 is restarted. Also, the information of this page is registered in the write page registration means 5.

In FIG. 9D, the memory copying means 1
Copy the remaining pages that have not been copied yet. FIG.
Since the page already copied by (c) has been deleted from the copy target page registration unit 4, the memory copy unit 1 does not copy this page again.

In the present embodiment, the processing can be reversed so that the data in the memory area B is copied to the memory area A in a similar manner.

Next, normal copy processing in the third embodiment will be described with reference to FIG.

At step U1, the (x-1) -th copy is started.

At step U2, the updated page information is registered in the write page registration means 4.

At step U3, the x-th copy is started.

In step U4, write protection is applied again to the copy source memory area.

In step U5, a copy target page registration unit 4 for designating a page to be copied is created from the page information registered in the write page registration unit 5.

At step U 6, the page designated by the copy target page registering means 4 is copied by the memory copying means 1.

At step U7, the memory copying means 1
Deletes the information of the copied page from the copy target page registration unit 4.

At step U8, it is determined whether the copying of all pages has been completed.

In step U9, if all pages have been copied in step U8, the copying is completed, and if there are remaining pages that have not been copied, the process in step U6 is repeated.

Next, processing in the case where an exception has occurred in the third embodiment will be described with reference to FIG.

At Step U10, the memory copying means 1
Detects the occurrence of write exception during memory copy.

In step U11, the write request recognition means 2 checks the page where the exception has occurred.

In step U12, it is determined whether the exception has occurred in a page in the memory area being copied.

In step U13, if the page of step U12 is in the memory area being copied, it is determined whether or not the page is registered in the copy object registration means 4.

In step U14, if the page of step U13 is registered in the copy object registration means 4, this page is copied by the priority memory copy means 3 and the information of this page is deleted from the copy object registration means 4. .

At step U15, the information of the page at step U13 is registered in the write page registering means 5.

In step U16, if the page where the exception has occurred is a page in the memory area being copied, the write protection of this page is removed.

At step U17, the exception process is completed.

As described above, according to the present embodiment, not all data in the copy area is copied, but pages a, b, and b updated from the time when the previous copy was started until the current copy was started. By setting only c and d to be copied, the number of pages to be copied can be kept to a minimum and the performance degradation due to copying can be reduced.

(Fourth Embodiment) FIGS. 12A and 12B show
The copy method and system of the present invention are applied to a checkpoint collection process of a highly reliable middleware,
This is an example of application to a specific system.

Here, an example of the high reliability middleware is ARTEMIS (Shirakihara, Hirayama, Kanai, “Design and Implementation of High Reliability Middleware ARTEMIS”, Information Processing Society of Japan OS Study Group, February 1997, Shirakihara, Hirayama , Kanai, Sato `` ARTEMIS: Advanced Reliable Dsitribut
ed Middleware System '' proc.of lnt Cont PDATA'97,1
June 997).

The high-reliability middleware periodically transfers checkpoint information of a process running on the primary computer 20 to the backup computer 30. When a failure occurs in the primary computer 20, the stored checkpoint information is saved. By restoring the process on the backup computer 30 based on the point information, non-stop operation of the process is realized.

At the time of checkpoint collection, various process configuration information is stored in the backup computer 30.
To the primary computer 2
0 Copy to the buffer prepared above. Memory data is one of them. Conventionally, all pages updated since the previous checkpoint collection were all
While copying to the buffer on 0, the processing of the process was interrupted. However, when ARTEMIS is applied to an application that frequently updates a large memory area, the amount of data to be copied to a buffer on the primary computer 20 at the time of checkpoint collection increases, which is a cause of performance degradation.

However, by applying the present embodiment, all the updated pages can be directly copied to the buffer on the backup computer 30 and the process can be restarted without waiting for the completion, so that performance improvement is expected. be able to.

Here, the time for transferring the memory data to the backup computer 30 is longer than the time for copying the memory data to the buffer on the primary computer 20. For this reason, conventionally, when memory data is directly transferred to the backup computer 30, the processing of the process is interrupted during that time, and the performance is greatly reduced. On the other hand, by applying the present invention, the processing of the process is reduced. Since the interruption is minimized, it is possible to prevent performance degradation.

Since the fourth embodiment shows a case where the third embodiment is applied to high-reliability middleware, a specific flow for memory copying follows the third embodiment.

Hereinafter, the flow of checkpoints when the present embodiment is applied to a system will be described with reference to FIGS.

At step V1, pages A and B are updated from the x-th check point.

At step V2, the (x + 1) th checkpoint is started (pages A and B are to be transferred), and at step V3, page A is transferred to the backup computer 30.
Transfer to

At step V4, page C is updated.

At step V5, the page B is transferred to the backup computer 30. At step V6, the (x + 1) th checkpoint is completed. At step V7, the pages A and D are updated.

In step V8, the (x + 2) th checkpoint starts (pages A, C, and D become transfer targets), and
In step V9, pages C and A are transferred to backup computer 30.

At step V10, the occurrence of a page D update request is detected.

In step V11, page D has been updated since the start of the x + 1-th checkpoint, and x + 2
Since it has not yet been transferred at the th checkpoint,
The request in step V10 is blocked, and page D is transferred to the backup computer 30 first.

In step V12, it is determined that the (x + 2) th checkpoint is completed, and in step V13, step V11
Executes the update request for the page D that has been blocked by.

As described above, in the present embodiment, the checkpoint information of the process running on the primary computer 20 is periodically transferred to the backup computer 30 in the high-reliability middleware, and a failure occurs in the primary computer 20. At this time, since the process is restored on the backup computer 30 based on the saved checkpoint information, it is possible to operate a necessary data copy without stopping the process.

The present invention is not limited to the above-described and illustrated embodiments, but rather the disk 40 in FIG.
Are magnetic disks, floppy (registered trademark) disks, hard disks, optical disks (CD-R
OM, CD-R, DVD, etc.), magneto-optical disk (MO
), A tangible storage medium that can store programs and that can be read by a computer, such as a semiconductor memory,
The storage format and shape may be any.

Further, the storage medium in the present invention is not limited to a medium independent of a computer, but also includes a storage medium in which a program transmitted via a LAN or the Internet is downloaded and stored or temporarily stored.

Further, the number of storage media is not limited to one, and the case where the processing in this embodiment is executed from a plurality of media is also included in the storage media of the present invention, and any media configuration may be used.

The computer according to the present invention includes a database and various types of storage devices as a copy source memory, and executes each process in the present embodiment based on a program stored in a storage medium. The present invention may be applied to any configuration such as an apparatus including one computer and a system in which a plurality of apparatuses are connected to a network.

The computer according to the present invention includes an arithmetic processing unit, a personal computer, a microcomputer, and the like included in the information processing device, and includes devices and devices capable of realizing the functions of the present invention by the program. Collectively.

[0121]

As described above, according to the present invention, even if writing to the copy source memory area occurs during memory copying, writing is blocked if the writing target extends over a wide range of pages. Since the time is short, it is possible to provide a data copy system, a data copy method, and a storage medium capable of greatly improving performance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a system including a computer to which the present invention is applied.

FIG. 2 is a diagram showing an application form of the data copy method of the present invention.

FIG. 3 is a diagram showing a method according to the first embodiment of the present invention.

FIG. 4 is a view showing a flowchart during normal processing according to the first embodiment;

FIG. 5 is a view showing a flowchart when an exception occurs in the first embodiment.

FIG. 6 shows a method according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a flowchart during normal processing according to a second embodiment.

FIG. 8 is a diagram illustrating a flowchart when an exception occurs according to the second embodiment.

FIG. 9 is a diagram showing a method according to a third embodiment of the present invention.

FIG. 10 is a diagram illustrating a flowchart during normal processing according to a third embodiment.

FIG. 11 is a diagram illustrating a flowchart when an exception occurs according to the third embodiment.

FIG. 12 is a diagram illustrating a method according to a fourth embodiment of the present invention and illustrating application of a highly reliable middleware to checkpoint processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Memory copy means 2 Write request recognition means 3 Priority memory copy means 4 Copy target page registration means 5 Write page registration means 10 Network 20 Primary computer 21 Database 30 Backup computer 31 Database 40 Disk

Claims (4)

[Claims] 1. Copy means for copying data in a copy source area on a copy source memory to a copy destination memory, and when a write request to the copy source memory occurs before a copy operation by the copy means is completed, the writing is performed. Recognizing means for recognizing an area in which the request has occurred; and when the area in which the write request has been recognized is not an already copied area, the data in the area is given priority over the copying operation by the copying means. Priority copy means for copying the copied area; copied area recognition means for recognizing the already copied area in the copy source memory; and the copied area in the copy source memory recognized by the copied area recognition means. Means for excluding data from the data copy system. . 2. When a write request to the copy source memory is issued before the operation of copying the data of the copy source area on the copy source memory to the copy destination memory is completed, the area where the write request has occurred is recognized. When the area where the recognized write request has occurred is not the already copied area, the data in the area is copied to the copy destination memory in preference to the copy operation, and the already copied area in the copy source memory is recognized and the recognition is performed. A data copy method in which the already copied area in the copy source memory is excluded from the copy source area. 3. The data copy method according to claim 2, wherein the copy operation is periodically repeated. 4. A computer-readable program which is applied to a computer system for copying data in a copy source area on a copy source memory to a copy destination memory and used for a system which executes a predetermined operation according to a program read from an external storage medium. The storage medium according to claim 1, wherein, when a write request to the copy source memory is issued before the operation of copying data in the copy source area on the copy source memory to the copy destination memory is completed, the area where the write request occurred. Recognizing, and when the area in which the write request recognized in this step is not the already copied area, copying the data of the area to the copy destination memory prior to the copy operation; and And recognizes the already copied area in the copy source. Excluding an already copied area in the memory from the copy source area; and a computer-readable storage medium storing a program for executing the following.