JP3822431B2 - Data copy system, data copy method, and storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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]
About.
[0003]
[Prior art]
Conventionally, when data on a memory is copied to another memory area on the same computer or a different computer, it is necessary to prevent the data on the copy source memory from being updated during copying. Therefore, until the copy is completed, the entire memory area of the copy source is locked to prohibit writing.
[0004]
[Problems to be solved by the invention]
As described above, while the 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, so that the size of the memory area to be copied increases. , The time during which writing is not possible becomes longer. This time becomes 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 processing for frequently updating and copying a large-sized memory area is performed, there is a problem that the memory copy time becomes a bottleneck and the performance cannot be improved.
[0006]
As described above, conventionally, when data in a memory is copied to another memory area, writing has been prohibited until copying of the entire memory area is completed, so that updating and copying to a large memory area are repeated. When this processing was performed, the copy time became a bottleneck and the performance did not improve.
[0007]
An object of the present invention is to provide a data copy system capable of reducing performance degradation associated with memory copy by shortening a write prohibition time for a copy source memory area even when copying data on a large size memory. Another object is to provide a data copy method and a storage medium.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a copy unit that copies data in a copy source area on a copy source memory to a copy destination memory;
A recognizing unit for recognizing an area where the write request is generated when a write request to the copy source memory is generated before the copy operation by the copy unit is completed;
Priority copy means for copying the data in the area to the copy destination memory in preference to the copy operation by the copy means when the area where the write request recognized by the recognition means is not an already copied area;
An existing copy area recognition means for recognizing an already copied area in the copy source memory;
Means for excluding an already copied area in the copy source memory recognized by the already copied area recognition means from the copy source area;
A data copy system comprising:
[0009]
According to a second aspect of the present invention, when a write request for the copy source memory is generated 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 is generated is stored. Recognize, and when the recognized write request area is not an 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. In the data copy method, the already copied area in the recognized copy source memory is excluded from the copy source area.
[0010]
The invention according to claim 3 is the data copy method according to claim 2, wherein the copy operation is repeated periodically.
[0011]
The invention according to claim 4 is applied to a computer system that copies data in a copy source area on a copy source memory to a copy destination memory, and is used in a system that executes a predetermined operation in accordance with a program read from an external storage medium. The computer-readable storage medium,
Recognizing an area where the write request has occurred when a write request to the copy source memory occurs before the operation of copying the data of the copy source area on the copy source memory to the copy destination memory is completed;
Copying the data in the area prior to the copy operation to the copy destination memory when the area where the write request recognized in this step is not an already copied area;
Recognizing an already copied area in the copy source memory and excluding the already copied area in the recognized copy source memory from the copy source area;
A computer-readable storage medium storing a program for executing the program.
[0012]
According to the invention according to each of the above-described claims, when copying is started, data in the copy source memory is copied, and there is a write request for an area where copying has been completed before the copying operation is completed. If there is a write request for an area that has not yet been copied, the area is preferentially copied and the copy of the area is considered complete and Therefore, it is possible to minimize the write prohibition time during copy execution and to prevent performance degradation.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
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 is connected to a network 10 such as the Internet, a public telephone line network or a private network, and a primary computer 20. The backup computer 30 is connected. Further, the primary computer 20 is equipped with hardware or software for performing a copy method described later. Of course, when such hardware or software is not provided, a program stored on the disk 40 is installed via the network 10 or directly, so that a method described later can be performed.
[0014]
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 includes one area on the memory such as the database of the primary computer 20. When data is copied to another area, data in a specific area on the memory such as the database of the primary computer 20 may be copied to a specific area on the memory such as the database of the backup computer 30.
[0015]
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. Show.
[0016]
FIG. 2B shows the latter example, in which the data in one area 21A on the database 21 of the primary computer 20 is copied to the area 31A on the database 31 of the backup computer 30. .
[0017]
The copy operation includes a one-time copy operation, a plurality of irregular copy operations, and a periodic repetitive copy. However, there is no essential difference in the copy operation itself.
[0018]
Each of the embodiments described below has a configuration according to the difference in copy destination and the frequency of the copy operation under the common data copy method described above.
[0019]
(First embodiment)
FIG. 3 shows a copying method and system according to the first embodiment of the present invention.
[0020]
In the present embodiment, before starting copying, the entire copy source memory area is write-protected, and when a write request is generated during copying, an exception handler which is the write request recognition means 2 is activated. . The exception handler recognizes the page where the write request has occurred from the address where the write exception has occurred.
[0021]
Hereinafter, the flow until all the data on the memory area A is copied to the memory area B will be described with reference to FIG.
[0022]
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 unit 1 in units of pages. This process continues until all pages in the memory area A that are write protected are copied to the memory area B. Pages that are not write protected are not copied. The memory copy unit 1 removes the write protection of the copied page.
[0023]
In FIG. 3 (b) following FIG. 3 (a), even while data copying by the memory copy unit 1 is being performed, writing to a page that has already been copied is permitted as it is.
[0024]
In FIG. 3 (c) following FIG. 3 (b), 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 recognition unit 2 After interrupting the processing of the memory copy unit 1, the preferential memory copy unit 3 is activated to copy the page first. After the copy is completed, the write protection of the page is removed to allow writing, and the processing of the memory copy unit 1 is resumed.
[0025]
In FIG. 3D subsequent to FIG. 3C, the memory copy unit 1 copies the remaining pages that have not yet been copied. Since the page already copied in FIG. 3C has been write-protected by the write request recognition unit 2, the memory copy unit 1 does not copy this page again.
[0026]
In the present embodiment, it is also possible to reverse the processing so that the data in the memory area B is copied to the memory area A by the same method.
[0027]
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 copy source memory area.
[0028]
In step S2, an exception handler, which is a write request recognition unit 2 for performing page fault processing when writing is performed on a page for which write protection is set, is set.
[0029]
In step S3, the memory copy unit 1 sequentially copies the data in the copy source memory area to the copy destination memory area.
[0030]
In step S4, it is determined in step S3 whether or not the next copy page is write protected.
[0031]
In step S5, if the page of step S4 is write protected, the memory copy means 1 copies the page and removes the write protection.
[0032]
In step S6, it is determined whether all pages have been copied.
[0033]
In step S7, if all pages have been copied in step S6, the copying is completed, and if there are any pages that have not been copied, the processing in step S3 is repeated.
[0034]
Next, processing when an exception occurs in the first embodiment will be described with reference to FIG. In FIG. 5, in step S8, the memory copy unit 1 detects that a write exception has occurred during the memory copy.
[0035]
In step S9, the write request recognition unit 2 examines the page where the exception has occurred.
[0036]
In step S10, it is determined whether the exception occurred is a page in the memory area being copied.
[0037]
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.
[0038]
In step S12, the exception process is completed.
[0039]
As described above, according to the present embodiment, when all the data on the memory area A is copied to the memory area B, the data on the copy source memory is copied when copying is started, and the copying operation is completed. During this period, if there is a write request for an area that has already been copied, it is allowed. If there is a write request for an area that has not yet been copied, the area is preferentially copied. Assuming that the copying of the area has been completed, the copying of those pages is suppressed again, so that the write prohibition time during the copy execution can be minimized and performance degradation can be prevented.
[0040]
(Second Embodiment)
FIG. 6 shows a copy method and system according to the second embodiment of the present invention.
[0041]
In the present embodiment, the entire copy source memory area is write-protected before copying is started, and an exception handler which is the write request recognition unit 2 is activated when a write request is generated during copying. This exception handler recognizes a page where a write request has occurred from an address where a write exception has occurred. Further, a copy target page registration unit 4 for designating a page to be copied is created.
[0042]
Hereinafter, a flow until all data on the memory area A are copied to the memory area B in the present embodiment will be described with reference to FIG.
[0043]
In FIG. 6A, the data on the memory area A is sequentially copied to the memory area B by page unit by the memory copying means 1. This process continues until all pages specified by the copy target page registration unit 4 are copied.
[0044]
The page information copied by the memory copy unit 1 is deleted from the copy target page registration unit 4.
[0045]
At the start of copying, all pages in the memory area A are registered in the copy target page registration unit 4.
[0046]
In FIG. 6B, if there is a write request for a page that has already been copied before the data copy by the memory copy unit 1 is completed, the write request recognition unit 2 immediately writes the page. Remove protection and allow writing.
[0047]
In FIG. 6C, 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 recognition unit 2 performs the processing of the memory copy unit 1. Is interrupted, the preferential memory copy unit 3 is activated to copy the page first, and the page information is deleted from the copy target page registration unit 4.
[0048]
After the copy is completed, the write protection of the page is removed to allow writing, and the processing of the memory copy unit 1 is resumed.
[0049]
In FIG. 6D, the memory copy unit 1 copies the remaining pages that have not yet been copied. Since the page already copied in FIG. 6C has been deleted from the copy target page registration unit 4, the memory copy unit 1 does not copy this page again.
[0050]
In the present embodiment, it is also possible to reverse the processing so that the data in the memory area B is copied to the memory area A by the same method.
[0051]
Next, normal copy processing in the second embodiment will be described with reference to FIG. In step T1, write protection is applied to the copy source memory area.
[0052]
In step T2, an exception handler is set which is a write request recognition unit 2 that performs page fault processing when writing is performed on a page for which write protection is set.
[0053]
In step T3, a copy target page registration unit 4 for designating a page to be copied is created.
[0054]
In step T4, the memory copy unit 1 copies the page specified by the copy target page registration unit 4.
[0055]
In step T5, the memory copy unit 1 deletes the copied page information from the copy target page registration unit 4.
[0056]
In step T6, it is determined whether or not all pages have been copied.
[0057]
In step T7, if all the pages are copied in step T6, the copying is completed, and if there is any page that has not been copied, the process of step T4 is repeated.
[0058]
Next, processing when an exception occurs in the second embodiment will be described with reference to FIG. In step T8, the memory copy unit 1 detects the occurrence of a write exception during the memory copy.
[0059]
In step T9, the write request recognition unit 2 examines the page where the exception has occurred.
[0060]
In step T10, it is determined whether or not the exception has occurred in a page in the memory area being copied.
[0061]
In step T11, if the page in step T10 is in the memory area being copied, it is determined whether or not the page is registered in the copy target registration unit 4.
[0062]
In step T12, when the page is registered in the page copy target registration unit 4 in step T11, the page is copied by the preferential memory copy unit 3, and the information on this page is deleted from the copy target registration unit 4.
[0063]
In step T13, if the page where the exception occurred is a page in the memory area being copied, the write protection of this page is removed.
[0064]
In step T14, the exception process is completed.
[0065]
As described above, according to the present embodiment, when all the data on the memory area A is copied to the memory area B, the data on the copy source memory is copied when copying is started, and the copying operation is completed. During this period, if there is a write request for an area that has already been copied, it is allowed. If there is a write request for an area that has not yet been copied, the area is preferentially copied. Assuming that the copying of the area has been completed, the copying of those pages is suppressed again, so that the write prohibition time during the copy execution can be minimized and performance degradation can be prevented.
[0066]
(Third embodiment)
FIG. 9 shows a copy method and system according to the third embodiment of the present invention.
[0067]
In this embodiment, instead of copying all the data in the copy area, only pages a, b, c, and d that have been updated between the start of the previous copy and the start of the current copy are set as the copy target. To do.
[0068]
The updated page is a page that has been write-protected by the write request recognition unit 2 since the start of the previous copy, and updated page information is registered in the write page registration unit 5.
[0069]
Also, before starting the copy from the memory area A to the memory area B, these update pages are also write-protected again so that the write request recognition means 2 can recognize that a write request has been received during the copy. Keep it like that.
[0070]
Further, a copy target page registration unit 4 for designating a page to be copied is created.
[0071]
Hereinafter, referring to FIG. 9, pages a, b, c, and d on memory area A that have been updated between the time when the previous copy is started and the time when the current copy is started are copied to memory area B. The flow until is explained.
[0072]
In FIG. 9A, the pages on the memory area A that have been updated by the memory copy unit 1 from the start of the previous copy to the start of the current copy are sequentially transferred to the memory area B in units of pages. Copy to. This process continues until all pages specified by the copy target page registration unit 4 are copied. The page information copied by the memory copy unit 1 is deleted from the copy target page registration unit 4.
[0073]
Note that the page information registered in the write page registration unit 5 is registered in the copy target registration unit 4 at the start of copying.
[0074]
In FIG. 9 (b), if there is a write request for a page that has not been updated since the start of the previous copy or a page that has already been copied before the data copy by the memory copy means 1 is completed, The write request recognizing means 2 immediately removes the write protection of the page and permits writing. Also, the information of this page is registered in the write page registration means 5.
[0075]
In FIG. 9C, if there is a write request for a page that has not yet been copied before the data copy by the memory copy unit 1 is completed, the write request recognition unit 2 performs the processing of the memory copy unit 1. Is interrupted, the preferential memory copy unit 3 is activated to copy the page first, and the page information is deleted from the copy target page registration unit 4.
[0076]
After the copy is completed, the write protection of the page is removed to allow writing, and the processing of the memory copy unit 1 is resumed. Also, the information of this page is registered in the write page registration means 5.
[0077]
In FIG. 9D, the memory copy means 1 copies the remaining pages that have not yet been copied. Since the page already copied in FIG. 9C has been deleted from the copy target page registration unit 4, the memory copy unit 1 does not copy this page again.
[0078]
In the present embodiment, it is also possible to reverse the processing so that the data in the memory area B is copied to the memory area A by the same method.
[0079]
Next, normal copy processing in the third embodiment will be described with reference to FIG.
[0080]
In step U1, the (x-1) th copy is started.
[0081]
In step U 2, the updated page information is registered in the write page registration unit 4.
[0082]
In step U3, the xth copy is started.
[0083]
In step U4, write protection is applied again to the copy source memory area.
[0084]
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.
[0085]
In step U6, the memory copy unit 1 copies the page specified by the copy target page registration unit 4.
[0086]
In step U 7, the memory copy unit 1 deletes the copied page information from the copy target page registration unit 4.
[0087]
In step U8, it is determined whether or not all pages have been copied.
[0088]
In step U9, if all pages have been copied in step U8, the copying is completed, and if there are any pages that have not been copied, the processing in step U6 is repeated.
[0089]
Next, processing when an exception occurs in the third embodiment will be described with reference to FIG.
[0090]
In step U10, the memory copy unit 1 detects the occurrence of a write exception during the memory copy.
[0091]
In step U11, the write request recognition unit 2 examines the page where the exception has occurred.
[0092]
In step U12, it is determined whether the exception occurred is a page in the memory area being copied.
[0093]
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 target registration means 4.
[0094]
In step U14, when the page of step U13 is registered in the copy target registration unit 4, this page is copied by the preferential memory copy unit 3, and information on this page is deleted from the copy target registration unit 4.
[0095]
In step U15, the page information in step U13 is registered in the write page registration means 5.
[0096]
In step U16, if the page where the exception occurred is a page in the memory area being copied, the write protection of this page is removed.
[0097]
In step U17, the exception process is completed.
[0098]
As described above, according to the present embodiment, the pages a, b, c, and d updated between the start of the previous copy and the start of the current copy, instead of copying all the data in the copy area. By making only the copy target, the number of pages to be copied can be kept to a minimum and performance degradation due to copying can be reduced.
[0099]
(Fourth embodiment)
FIGS. 12A and 12B show a case where the copy method and system of the present invention are applied to the checkpoint collection processing of high-reliability middleware, which is an example of application to a specific system.
[0100]
Here, as an example of high-reliability middleware, there is ARTEMIS (Shirakihara, Hirayama, Kanai “Design and Implementation of High-Reliability Middleware ARTEMIS” Information Processing Society of Japan, February 1997, Shirakihara, Hirayama, Kanai, Sato "ARTEMIS: Advanced Reliable Dsitributed Middleware System" proc.of lnt Cont PDATA '97, June 1997).
[0101]
Such high-reliability middleware periodically transfers checkpoint information of processes operating on the primary computer 20 to the backup computer 30 and stores the stored checkpoint information when a failure occurs in the primary computer 20. By restoring the process on the backup computer 30 based on the original, non-stop operation of the process is realized.
[0102]
Here, at the time of taking a checkpoint, various process configuration information is transferred to the backup computer 30. First, it is copied to a buffer prepared on the primary computer 20. Memory data is one of them. Conventionally, the process processing is interrupted while all the pages updated since the last checkpoint collection are copied to the buffer on the primary computer 20. However, when ARTEMIS is applied to an application that frequently updates a large memory area, the amount of data copied to the buffer on the primary computer 20 at the time of checkpoint collection increases, which has been a cause of performance degradation.
[0103]
However, by applying this 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 an improvement in performance can be expected. .
[0104]
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 the memory data is directly transferred to the backup computer 30, the process processing is interrupted during that time, so that the performance is significantly reduced. Since interruptions are minimized, performance degradation can be prevented.
[0105]
Since the fourth embodiment shows a case where the third embodiment is applied to high-reliability middleware, the specific flow at the time of memory copy follows that of the third embodiment.
[0106]
Hereinafter, the flow of check points when the present embodiment is applied to a system will be described with reference to FIGS.
[0107]
In step V1, pages A and B are updated from the xth checkpoint.
[0108]
In step V2, the x + 1th checkpoint is started (pages A and B are to be transferred), and step V3 and page A are transferred to the backup computer 30.
[0109]
In step V4, page C is updated.
[0110]
Transfer page B to backup computer 30 at step V5
In step V6, the (x + 1) th checkpoint is completed, and in steps V7, pages A and D are updated.
[0111]
In step V8, the (x + 2) th checkpoint is started (pages A, C, and D are to be transferred), and pages C and A are transferred to the backup computer 30 in step V9.
[0112]
In step V10, occurrence of an update request for page D is detected.
[0113]
In step V11, page D has been updated since the start of the (x + 1) th checkpoint and has not yet been transferred at the (x + 2) th checkpoint. Therefore, the request in step V10 is blocked, and page D is first transferred to the backup computer 30. Forward.
[0114]
In step V12, the (x + 2) th checkpoint is completed, and in step V13, an update request for page D that has been blocked in step V11 is executed.
[0115]
As described above, in the present embodiment, checkpoint information of processes operating on the primary computer 20 is periodically transferred to the backup computer 30 in the high-reliability middleware, and when a failure occurs in the primary computer 20, Since the process is restored on the backup computer 30 based on the stored checkpoint information, it is possible to operate the necessary data copy without stopping the process.
[0116]
The present invention is not limited to the embodiment described above and illustrated, and the disk 40 in FIG. 1 is a magnetic disk, floppy disk, hard disk, optical disk (CD-ROM, CD-R, DVD, etc.) as a storage medium. As long as it is a tangible storage medium that can store a program and can be read by a computer, such as a magneto-optical disk (MO, etc.), a semiconductor memory, etc., the storage format and shape may be any.
[0117]
Furthermore, 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.
[0118]
Further, the number of storage media is not limited to one, and the case where the processing in the present embodiment is executed from a plurality of media is also included in the storage media in the present invention, and the media configuration may be any configuration.
[0119]
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 according to the present embodiment based on a program stored in a storage medium. The configuration may be any of an apparatus including one computer, a system in which a plurality of apparatuses are connected to a network, and the like.
[0120]
The computer according to the present invention is a generic term for devices and apparatuses that can realize the functions of the present invention by a program, including arithmetic processing devices, personal computers, microcomputers, and the like included in information processing devices. Yes.
[0121]
【The invention's effect】
As described above, according to the present invention, even when a write to the copy source memory area occurs during the memory copy, the write is blocked for a short time when the write target extends over a wide range of pages. 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 mode of the data copy method of the present invention.
FIG. 3 shows a method according to the first embodiment of the present invention.
FIG. 4 is a flowchart illustrating normal processing according to the first embodiment.
FIG. 5 is a view showing a flowchart when an exception occurs according to the first embodiment.
FIG. 6 is a diagram showing a method according to a second embodiment of the present invention.
FIG. 7 is a flowchart illustrating normal processing according to the second embodiment.
FIG. 8 is a view showing 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 flowchart illustrating normal processing according to the third embodiment.
FIG. 11 is a view showing a flowchart when an exception occurs according to the third embodiment.
FIG. 12 is a diagram showing a method according to a fourth embodiment of the present invention and showing application of high-reliability middleware to checkpoint processing;
[Explanation of symbols]
1 Memory copy means
2 Write request recognition means
3 Preferential 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 discs

Claims (4)

A copy means for copying the data in the copy source area on the copy source memory to the copy destination memory;
A recognizing unit for recognizing an area where the write request is generated when a write request to the copy source memory is generated before the copy operation by the copy unit is completed;
Priority copy means for copying the data in the area to the copy destination memory in preference to the copy operation by the copy means when the area where the write request recognized by the recognition means is not an already copied area;
An existing copy area recognition means for recognizing an already copied area in the copy source memory;
A data copy system comprising: means for excluding an already copied area in the copy source memory recognized by the already copied area recognition means from the copy source area. When a write request to the copy source memory is generated 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 area where the write request has occurred is recognized, and the recognized write request When the area where the error occurred is not an 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 recognized copy source memory is copied. A data copy method characterized in that an already copied area is excluded from the copy source area. 3. The data copy method according to claim 2, wherein the copy operation is repeated periodically. The computer-readable storage medium that is applied to a computer system that copies data in a copy source area on a copy source memory to a copy destination memory and that is used in a system that executes a predetermined operation in accordance with a program read from an external storage medium Because
Recognizing an area where the write request has occurred when a write request to the copy source memory occurs before the operation of copying the data of the copy source area on the copy source memory to the copy destination memory is completed;
Copying the data in the area prior to the copy operation to the copy destination memory when the area where the write request recognized in this step is not an already copied area;
Recognizing an already copied area in the copy source memory and excluding the already copied area in the recognized copy source memory from the copy source area;
The computer-readable storage medium which memorize | stored the program for performing this.

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