JP2006127546A - Method for operating computer system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for performing backup of a storage device shared by some application programs without influencing on execution of the application programs. <P>SOLUTION: The method comprises a backup process including processing for maintaining recording of change to be performed to data in the storage device 16 while executing the backup. It permits that other processing usually keeps updating the storage device, thus, the recording is used for assuring that data to be referred to in the backup process is not changed during execution of the backup process while avoiding that delay is generated by being connected with some file lock technology. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a computer system, and in particular, warns of the possibility that a storage device will fail, data will be garbled, lost, or recently "infected with a computer virus". Therefore, it relates to a method for providing a backup copy of data stored in a storage device. The present invention is particularly concerned with providing backups of personal computers (PCs).

  Conventionally, in a simple manner, in a computer system having a storage means called a hard disk or a fixed disk for a single user, only one application program can access the storage means at any time. The backup work of data stored in the storage means is performed by an application program that exclusively uses the storage means during execution of this backup work. This is because in such a state, no other application can run until the backup application is terminated.

  If you introduce a multitasking environment in which several applications can be operated simultaneously or a network system that allows several users to share the same computer resources, one or more applications can access the same storage means at one time Such a situation may occur. If such a situation occurs, there is a possibility of a collision between applications. For example, one application may update or delete a file that is currently used by another application. This can lead to confusion, possibly disrupting the storage means and resulting in data loss.

  Methods known as “file locks” and “record locks” have been introduced to the operating system to prevent one or more applications from trying to write a file in the file lock example. In addition, in the record lock example, two applications are prevented from trying to update a file having the same area. These methods are sufficient for most applications. Especially if each application makes only relatively small changes to the shared file, and therefore does not slow down other applications trying to access locked files and records.

  However, an application for periodic data backup in a computer system that shares storage means is a special case.

  The smallest unit of data that can be backed up is one file. This is because neither the backup application nor the operating system knows its internal structure just because the file is tied to some application program.

In addition, the backup copy of the file must be an exact copy of the original at a particular time. However, file copying is not an instantaneous process, and the time required for copying depends on the size of the file and the speed of the copying operation. This is a problem unless the backup application recognizes that another application can update the file during copying.

  To copy a file, the backup application allocates a random access memory (RAM) area as a transfer buffer, reads the original file block into the buffer, and writes the buffer contents to secondary storage means. And alternately. Unless the file is extremely small, the transfer buffer will fill up several times, and the copy operation will require many read / write operations to make a complete copy of the file.

  A potential problem caused by the file being updatable during copying will be shown by taking into account the example of a file being copied every 10 blocks of a series. If blocks 1 through 5 have already been copied and the file is updated by a process that requires changes to the files corresponding to blocks 3 and 8, then the copying process will copy the changes to block 8. However, changes to block 3 will not be copied because this block has already been copied before the process is performed. This backup copy will therefore only contain partial processing, which would make the backup copy useless at all. This is because the application responsible for this may recognize the file as invalid.

  U.S. Pat. No. 5,086,502 presents a backup method of individual write operations, such as can be achieved by doing a double write operation to secondary storage means. In addition to this method, there are two other ways to back up files in a computer system with a shared storage means: i) lock files during backup.

  This prevents other users from trying to update the file by denying write access. If another user has already had write access, the backup application must skip the file or wait for exclusive write access to be performed.

ii) Discover changes to the file.
After copying the file, this backup application can use the operating system to check if any changes occurred during the copy process. If there is a change, the copy must be repeated or the file must be skipped.

  Neither of the latter two methods provides a sufficient solution. This is because many files (especially database files) are constantly in use. Furthermore, these two methods require that the user be effectively locked out during backup. In addition, secondary storage and operating system combinations rarely maintain transfer rates in excess of 15 megabytes (Mb) per second, and therefore the time required to copy large files can be significant. is there.

  Although some application programs address this problem by providing a way to securely back up their own files in a shared environment, each procedure is different. In order to back up the entire storage means, the backup application therefore needs to know how each different provided procedure works, or must rely on manual interruptions at the appropriate points.

  In this way, since the backup application has to back up the whole file, and the file cannot be updated during the backup operation by other application programs, the backup method as described above is shared. Will bring a delay to computer systems equipped with storage means. This is especially true when large files are backed up.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, a method for operating a microprocessor-based computer system comprising a random access memory, a central processing unit, and storage means comprises the following steps: In other words, a procedure for providing a backup process that operates on the computer system, transmits a start signal and a stop signal, and can perform at least one backup reading operation of reading original data from the storage means; To cause the central processing unit to execute at least one normal writing operation of periodically writing to the main area of the storage unit and at least one normal reading operation of reading data from the storage unit Stored in the memory in the central processing unit. In order to retain the original data that may be overwritten by the writing operation while intermediately capturing the writing operation after receiving the start signal and the procedure for giving the initial command to store the data in the sub area of the storage means Performing an intermediate capture operation of writing, holding a record of the write to the sub-region, and performing data from one of the main region and the sub-region according to the record during one of the backup and normal read operations Each of the steps in which the record is queried so that the backup process retains the original data in a state prior to the start signal being sent.

  Preferably, the record comprises a delta area in which the first data is stored, and an allocation reference that relates the actual position of the first data to the planned position. Alternatively, second data is recorded in the delta area, and other applications may continue to write to the scheduled location of the storage device.

  The delta area is preferably a different area of the same storage device, such as a hard disk. Additional tasks for carrying out the present invention are conveniently stored and run at the operating system level of the computer system.

  It will be apparent to the user that the software for performing the method of the present invention does not affect the application software if it is stored at the operating system level.

  With respect to the recording, this includes recording the first data, recording its scheduled location on the storage device, and recording its actual location, and the method further includes the scheduling. A procedure of acquiring the second data from a predetermined position.

  Preferably, the start command is issued prior to the backup application program to start backup, and preferably, the stop command is issued after the backup is completed.

  This backup record can be stored in various storage means, for example a tape drive, an optical disk, or other area of a basic storage medium. Once a backup has been made, it will be restored in a conventional manner.

  According to a second aspect of the present invention, a method for supplying data to a backup process running on a microprocessor-based computer system comprising a random access memory, a central processing unit, and a storage means comprises: Each procedure consists of at least one normal operation in which data is periodically written to the main area of the storage means by holding the central processing unit in the central processing unit held in the memory. A procedure for giving an initial command for performing a writing operation of the data and at least one normal reading operation of reading data from the storage means, a procedure for receiving a start signal from the backup process, and after receiving the start signal , The original that could be caught by the above writing work and overwritten by the above writing work Perform an intermediate capture operation of writing data to the sub-area of the storage means to hold the data, hold a record of the write to the sub-area, and execute one of the backup and normal reading operations A procedure to query the record to read data from one of the main area and the sub-area from time to time according to the record, whereby the backup process keeps the original data in the state before the start signal was sent And each procedure.

  According to a third aspect of the present invention, an improvement to a microprocessor-based computer system including a random access memory, a central processing unit and a storage means is capable of transmitting a start signal and a stop signal, Means for operating a backup process capable of executing at least one backup reading operation of reading original data from the storage means and the central processing unit, and periodically storing data in the main area of the storage means Means for performing at least one normal writing operation of writing data to the memory and at least one normal reading operation of reading data from the storage means, means for receiving the start signal, and the start signal After receiving this, execute the intermediate capture operation of capturing the above write operation as an intermediate Therefore, in order to hold the original data that may be overwritten by the writing operation, the data is written to the sub area of the storage means, the record of the writing to the sub area is held, the backup and the normal Querying the record to read data from one of the main area and the sub-area according to the record when executing one of the reading operations, whereby the backup process is in a state before the start signal is transmitted For storing original data.

The invention will be described below in an exemplary manner with reference to the figures.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring to FIG. 1, a personal computer 10 typically includes a central processing unit 12, a random access memory 14, and a non-volatile storage device in the form of a hard disk drive 16. Composed. In this example, a tape device 18 is connected to the computer 10 as backup storage means.

  In accordance with the present invention, the backup program application unit is responsible for normal reading from and writing to the disk drive 16 to control the flow between the disk drive 16 and other parts of the computer. Each operation is formed as a recording process for intermediate capture.

Before starting a backup copy of a file, the recording process is run by the backup application to redirect all disk write operations to another area of the disk 16, the so-called “delta area”. The delta mapping table holds all disk write operations redirected to the delta area. This table holds the mapping (correspondence) between the scheduled destination on the disk 16 and the actual storage location in the delta area of the data associated with each disk writing operation. .

  If the next writing operation has already occurred in the area having the description item material in the table, the old data in the delta area can be overwritten by new data. In this method, the data on the main part of the disk is not changed during the backup copy. This is because all changes are redirected to the delta region.

  When a disk read operation is requested from the backup application, it is performed unchanged, so that data returning to the backup application can come from the original area on the main part of the disk.

  However, when a disk read operation is requested from another application, the recording process first includes the table to know whether the process has started to supplement the write operation in the middle and thereafter a disk write to the area has occurred. If so, the read operation is redirected to a corresponding position in the delta region. If no write operation occurs, i.e. no data has changed since the beginning of the interim supplement of the write operation, the read operation is performed unchanged.

  In this way, changes to the data stored on the disk 16 are observed as usual by all applications, not just backup applications. The backup application observes data that does not change until a command is issued to stop the recording process that intervenes in reading and writing operations.

  When the backup copy operation is complete, the recording process is run to return the computer to normal operation. This restoration step is completed by applying the changes held in the delta area to a unique original data area in the main part of the disk 16 using the correspondence held in the table. While the delta change is applied, the disk write operation continues to be captured as described above. When the writing operation as applied to the original data area ceases, the intermediate capture of the writing operation is stopped and the system operates normally.

  As a further improvement, if the record is maintained in the range that the backup copy process has advanced, it will no longer matter whether the data has changed, so the software can After the backup is completed, the writing operation to the main part of the disk 16 can be allowed to be performed without change. This reduces the delta mapping table. In addition, if the area on the main part of the disk to which the work is directed is already the subject of the description item in the table, the description item is easily deleted, so that the restoration stage can be performed. The time it takes will be reduced.

  The present invention has been used in particular for IBM compatible personal computers, ie, systems based on Intel processor chip models 8086, 8088, 80286, 80386, 80486, and Pentium® and similar microprocessors. Applicable to many personal computers. In such a computer, whenever a program tries to access a file, it calls a standard routine that writes data to disk.

In the case of a DOS operating system, this routine, known as interrupt 21 hex (INT21h), is an essential part of the operating system. The action taken by the routine depends on the parameters transmitted to the routine on the entrance. This routine is shown in FIG. 2A as INT 21h, which forms the operating system part in the system memory mapping table, and the INT 21h entry point is indicated by an arrow. To perform the more preferred method according to the present invention, additional program code is added to the operating system at the interface level as shown in FIG. 2B. This is actually CONFIG. Using the SYS file, it is loaded into the computer as a device driver.

  This additional software has the effect of an instruction to write data to be replaced by the instruction selection set. Similar techniques will be familiar with the intermediate capture of the instruction to read data from the disk and replacing it with an instruction selection set.

  A related series of operations is shown in the flowchart of FIG. When receiving a call command for INT21h, the program first checks whether the call command is a write call command. If so, the program checks in step 20 whether intermediate capture of the write call command can occur. If not, the data is written to the original data area 24 (step 22).

  If the write call command has been captured in the middle, the program checks in advance in the delta mapping table (step 26) whether or not writing has been made to the area of the original file 24. If writing was done in advance (step 28), that portion of the delta area 30 previously mapped to that portion of the original file 24 in the delta mapping table would overwrite the new data. (Step 32).

  If a write call command has been captured intermediately and no previous write has been made to that portion of the original file 24, the write is added to the table and a new area of the delta area Are assigned to the portion of data (step 34). Thereafter, the data is written into the new data area (step 36).

  If the call command is a read call command, the program checks in step 38 whether there is an intermediate capture of the read call command. If not, data is read from the original file 24 (step 40).

  If the program has captured a read call command, it first checks in step 42 whether the call command came from a backup application program. If the call command came from the backup application, the program goes to step 40 and data is read from the original file 24.

  If the call command does not come from the backup application, the program determines whether writing to the area of the original file 24 corresponding to the read call command has been redirected to the delta area. Confirm with the delta mapping table (step 44).

If it has not been redirected, the program returns to step 40 and the data is read from the original file 24. If the read has been redirected, the data is read from the normal portion of the delta region 30 (step 48).

  In the second embodiment of the present invention, instead of keeping the updated data in the delta area, when reading and writing operations are captured in the middle of the recording process, the first time to a special area of the file The original data is retained in the delta area and the original file is allowed to be modified when the data is written. An item is set in the mapping table that displays the original contents of the original file stored at that time in the delta area. Any subsequent writing to the same area of the file will be ignored by the recording process. A read request from the backup application is then redirected to the delta area if the mapping table indicates that the area of the original file has been overwritten.

  In FIG. 4, this second embodiment is represented by a flowchart. This chart is similar to that of FIG. 3 with respect to steps having the same reference numbers indicating similar operations.

  The differences between the two figures (3 and 4) are as follows: In step 60, if a read intermediate capture is in operation (step 38), and the read is from the backup application. If not, the data is read from the original data area. This is the reverse of step 42 in the previous embodiment.

  An additional step 62 is inserted after step 28 reading data from the original data area before it is first overwritten.

  Step 36 of the first embodiment is modified to be a new step 64 that incorporates additional writing of the data read in step 62 to the delta region.

  Step 32 has been modified to be a new step 66 that no longer redirects data to the delta area, but instead writes data to the original data area.

  This second method is slower than the first, because each file write request is one time as opposed to one redirect write of the first method. This is because it is read and written twice.

  However, this second method does not require any changes that should be applied to the original file once the backup is complete and that are retained in the delta area. The delta mapping table and the data held in the delta area can be easily discarded. In addition, due to this difference, the data supply need not be restored from catastrophic situations (such as power interruptions) that occur when delta changes are not fully applied to the original data.

  In the example where the method described above forms a backup application, the intermediate capture of the read operation can occur in the backup application and does not require the use of operating system routines.

When the computing environment confirms that a particular user who wishes to perform a backup is the principal, the method also recognizes the user, and simply copies the user's file in the manner described above. It also includes the procedure of just backing up. This eliminates the need for intermediate capture of all data processing, but only those related to the user.

FIG. 1 is a block diagram of a personal computer and a cartridge tape drive. 2A and 2B are block diagrams of system memory maps at the operating system level of a typical personal computer and a computer operating in accordance with the method of the present invention, respectively. FIG. 3 is a flowchart of a method for recording data in a backup operation. FIG. 4 is a flowchart of a second embodiment of the method of FIG.

Claims (20)

A method for providing data to a backup process running on a computer system operating on the basis of a microprocessor comprising a random access memory, a central processing unit and storage means,
It is stored in the memory for causing at least one normal writing operation to periodically write data to the main area of the storage means and at least one normal reading operation to read data from the storage means. Providing the initial instruction to the central processing unit;
Receiving a start signal from the backup process;
After receiving the start signal, intermediate capture of the write operation is performed, and intermediate capture operation of writing data to the sub-area of the storage means is performed to store original data that may be overwritten by the write operation. The primary record written in the sub-area is stored, and data read from one of the main area and the sub-area according to the primary record when executing one of the backup and the normal reading operation Querying the primary record, thereby providing the backup process with original data stored in a state prior to the initiation of the start signal;
A secondary record indicating the advanced range of the backup process is stored, and when a command for writing to the storage means is received, the portion written in the main area of the storage means is backed up by the backup process. Determining from the secondary recording, and allowing the writing operation to the main area of the storage means without intermediately capturing the writing operation when the portion is backed up. Method. The normal writing operation data is written to the sub-area, and the primary recording includes a recording of a position designated for the normal writing operation of the main area and a recording of the actual position of the sub-area, The method of claim 1, further comprising obtaining the stored original data from the main area. After receiving a stop signal from the backup process, at least one recovery reading operation to read data from the actual position of the sub-region and at least one recovery writing to recover the data to the designated position of the main region The method includes the steps of: performing an operation according to the primary record, and ending the intermediate capture operation to intermediately capture the write operation when all data has been restored to a designated position in the main area. The method described. The method of claim 2, wherein the main area and the sub-area are different areas of a single storage device. Before normal writing data is written to the main area, the stored data is read from the main area and written to the sub area, and the primary recording is a record of the previous position of the original data of the main area. The method of claim 1, further comprising: acquiring the stored original data from the actual position. 6. The method of claim 5, further comprising terminating the intermediate capture operation for intermediate capture of the write operation after receiving a stop signal from the backup process. The method according to claim 6, wherein the main area and the sub-area are different areas of a single storage device. The method of claim 1, wherein instructions relating to intermediate capture operations are executed at a basic input / output system (BIOS) level. The method of claim 1, wherein the instructions relating to the intermediate capture task are executed at an operating system interface level. The method further includes the step of providing a backup process that can be executed on the computer system to transmit a start signal and a stop signal and to perform a backup reading operation of reading the original data from the storage means at least once. Item 2. The method according to Item 1. The method according to claim 10, wherein a start signal is transmitted before the backup process is started on the storage device, and a stop signal is transmitted after the backup process is completed. The method further includes the step of deleting, from the primary record, a description item related to the main area portion of the storage means backed up by the backup process when a backup process is being executed and in response to a further write command. Item 2. The method according to Item 1. An operating method of a computer system that operates based on a microprocessor comprising an instruction memory, a central processing unit, and storage means,
Providing a backup process operable on the computer system and capable of issuing at least one start signal;
Providing the central processing unit with an initial instruction stored in the memory to cause at least one normal writing operation to periodically write data to the main area of the storage means;
After receiving the start signal, the writing operation is intermediately captured, and in the intermediately captured writing operation, the designated data at a position of the main area of the storage means is set at a position of a sub area of the storage means. Performing the intermediate capture task to write while maintaining the written record in the sub-region and the portion of the corresponding main region;
In order to determine whether or not the intermediately acquired write operation exists for the write data instructed to the same main area portion as the currently intermediately acquired write operation, the intermediately acquired write operation Including the step of querying the record,
(A) if present, in the previous intermediate capture operation, overwrites new data with data previously written in the portion of the sub-area of the storage means;
(B) If not, add to the record and write the new data to the sub-area,
Accordingly, the backup process includes a step of maintaining a copy of the original data stored in a state before the start signal is transmitted. After receiving the stop signal, at least one recovery reading operation is performed to read data from the sub-area, and at least once to restore the data to a designated position in the main area. Performing recovery writing according to the above record;
14. The method of claim 13, further comprising the step of ending the intermediate capture operation that intermediately captures the write operation when all data has been restored to a designated location in the main area. A method of operating a computer system operating on a microprocessor, comprising an instruction memory, a central processing unit, and storage means,
Providing a backup process operable on the computer system and capable of issuing at least one start signal;
Providing the central processing unit with an initial instruction stored in the memory to cause at least one normal writing operation to periodically write data to the main area of the storage means;
After receiving the start signal, an intermediate capture operation is performed to intermediately capture the write operation. In the intermediate captured write operation, before writing new data into the main region portion of the storage means, Reading the data in the portion and writing the data in the sub-region portion of the storage means while holding the written record in the sub-region and the record written in the corresponding position in the main region; ,
The intermediate captured write operation is a query of the record to determine whether there is a previous intermediate captured write operation for write data in the same main area portion as the current intermediate captured write operation. And
(A) if present, overwrites the data previously written in the main area of the storage means with the new data in the previous intermediate capture write operation;
(B) If not, read the stored data from the main area, write it to the sub area, add it to the record and write the new data to the main area, thereby starting the backup process Maintaining a copy of the original data stored prior to the signal being sent. After receiving the stop signal, at least one recovery reading operation is performed to read data from the sub-region, and at least one recovery writing operation is performed to record data to a designated position in the main region. Steps to perform according to
16. The method according to claim 15, further comprising the step of terminating the intermediate capture operation for intermediate capture of the write operation when all data has been restored to a designated position in the main area. An apparatus for the operation of a computer system operating on the basis of a microprocessor comprising an instruction memory, a central processing unit and storage means,
Backup means capable of transmitting a start signal at least once;
Means for providing the central processing unit with an initial instruction stored in the memory in order to execute at least one normal writing operation for periodically writing data to the main area of the storage means;
After receiving the start signal for executing the intermediate acquisition operation for intermediate acquisition of the write signal, in the intermediate acquisition write operation, the data designated in the main area portion of the storage means is Means for writing to the portion of the sub area of the storage means, while holding the record written to the sub area, and the record written to the corresponding main area,
The execution means further queries the record to determine whether there is a previous intermediate captured write operation for write data designated in the same main area portion as the intermediate captured write operation this time. And
(A) if present, in the previous intermediate capture write operation, overwrite the new data previously written in the sub-area of the storage means;
(B) If not, add to the record and write the new data to the sub-area,
Accordingly, the backup process includes a means for holding a copy of the original data stored in a state before the start signal is transmitted. An apparatus for the operation of a computer system operating on the basis of a microprocessor comprising an instruction memory, a central processing unit and storage means,
Backup means capable of transmitting a start signal at least once;
Means for providing the central processing unit with an initial instruction stored in the memory in order to execute at least one normal writing operation for periodically writing data to the main area of the storage means;
After receiving the start signal, an intermediate capture operation is performed to intermediately capture the write operation. In the intermediate captured write operation, before writing new data into the main region portion of the storage means, Means for reading the data of the part and writing to the sub-area part of the storage means, while holding the record written to the sub-area and the record written to the corresponding main area,
The execution means further refers to the record in order to determine whether or not there is a writing operation that has been captured in the previous intermediate period, with respect to writing of the same portion of the main area as the writing operation that has been intermediately captured this time,
(A) if present, overwrites new data previously written in the main area of the storage means in the previous intermediate capture write operation;
(B) If not present, read the stored data from the main area, write it to the sub area, add to the record, and write new data to the main area,
Thus, the backup step comprises means for holding a copy of the original data stored in a state before the start signal is transmitted. A computer system that operates based on a microprocessor comprising a random access memory, a central processing unit, and storage means,
Means for performing a backup process capable of transmitting a start signal and a stop signal, and for performing at least one backup reading operation in order to read the original data from the storage means;
Regularly perform a normal write operation for writing data to the main area of the storage means at least once, and execute a normal read operation for reading data from the storage means at least once in the central processing unit. Means to
Means for receiving the start signal;
After receiving the start signal, an intermediate capture operation for intermediately capturing the write operation is performed, and data is written to the sub area of the storage means to protect the original data from being overwritten by the write operation. Means for retaining the written primary record;
In order to read data from one of the main area and the sub area, the primary record is queried, so that when the backup process is executed, it is stored in the state before the start signal is transmitted to the backup process. Provided with the original data provided,
After the start signal, means for storing a secondary record indicating a range in which the backup process has progressed, and when the write operation command to the storage means is received, the main area of the storage means that has been written It is determined from the secondary recording whether or not the part has been backed up by the backup process, and if the part is backed up, the writing operation for writing to the main area of the storage means is intermediately captured. And means for accepting without doing so. Means for deleting during the backup process and upon a response to a further write command, a description that is backed up by the backup process, mentioned in the further write command and relating to the main area portion of the storage means from the primary record; The apparatus of claim 19, comprising:

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