KR100285534B1 - How computer systems work - Google Patents

Abstract

The present invention is a computer system, in particular a microcomputer system, having a storage device divided between a plurality of application programs, comprising a backup process comprising a process for maintaining a record of changes to the data on the storage means during the backup process. It is about how to operate. The record is used to ensure that the data detected by the backup process does not change during execution while other processes continue to update the storage, thereby preventing delays associated with file locking techniques. Additional operations are performed at the operating system interface level of the microcomputer in a manner that does not affect the normal use of the computer.

Description

How computer systems work

1 is a block diagram of a personal computer and a cartridge tape drive.

2 (a) is a schematic diagram of a system memory diagram at an operating system stage of a typical personal computer.

2 (b) is a schematic diagram of system memory at an operating system stage of a computer modified to operate in accordance with the method of the present invention.

3 is a flowchart of a data recording method in a backup operation, and

4 is a flowchart of a second embodiment of the method of FIG.

* Explanation of symbols for main parts of the drawings

10 computer 12 central processing unit

14: RAM 16: Memory

24: original data area 30: delta area

[Background of invention]

The present invention relates to a method of operating a computer system, and in particular to a backup copy of data stored in a storage device in order to protect it from the possibility that the storage device is defective or the data is destroyed, destroyed, or recently infected with a `` computer virus ''. backup copy).

The present invention relates in particular to backup preparation for personal computers (P.C).

In a simple single-user computer system that typically includes storage means such as a fixed hard disk, only one application program is accessed to the storage at any given time. In such an environment, other applications cannot be operated until the backup application is terminated, so that the data stored in the storage device by the application program exclusively uses the storage means during the backup operation. The backup job takes place.

With the introduction of a multi-tasking environment where multiple applications can run simultaneously and a network system that allows multiple users to share the same resources, there is a need for more than one application to simultaneously access the same storage. do. In this case, there is a possibility of collision between applications. For example, an application may modify or remove a file currently being used by another application. This can lead to memory disruption, potentially damage, and eventually destruction of data.

Known as ″ file lock ″ and ″ record lock ″, which prevents more than one application from writing to a file when locking a file and preventing two applications from deforming the same area of a given file when locking a record. It is introduced in the operating system. This approach is very complicated for most applications, especially if each application only results in relatively small variations to the split file and does not seriously delay other applications trying to access locked files or records. However, there is a special case of an application for periodically backing up data in a computer system in which storage means are partitioned.

The smallest unit of data that can be backed up is a single file because the backup application and operating system do not know the internal structure of the file because it can be combined with any application program.

In addition, the backup copy of a file must be an image that is not the same as the original at any given moment. However, copying a file is not instantaneous and the time required for copying will depend on the file size and copy speed. If the backup application does not prevent other applications from modifying the file during the copy operation, problems will arise.

In order to copy a file, a backup application is allocated to a RAM area of a transfer buffer, selectively reads a block of an original file, moves it to a buffer, and writes the contents of the buffer to a second storage means. If the file is not very small, the transfer buffer must be filled several times and multiple reads and writes must be made to make a complete copy of the file. Taking a file copied into a series of 100 blocks as an example, it explains what potential problems are caused by file deformation during the copy process. If the file is modified by a transaction to transform the file corresponding to the third and eighth blocks after the files from the first to fifth blocks have already been copied, the modified one can be copied to the eighth block. Although the third block is already copied before the transaction, the transform cannot be copied to the third block. Therefore, such a backup copy will contain only a partial transaction that renders the entire backup copy useless, and the owner of the application will probably think the file is corrupted.

U. S. Patent No. 5,086, 502 discloses a method of backing up each write operation by making a double write operation in the second storage means. In addition to these methods, two other methods of backing up files on a computer system with partitioned storage are disclosed:

1) Lock files while backing up.

This denies other users' write access, preventing the file from being altered by other users. If write access has already been made by another user, the backup application will either skip the file or wait for exclusive write access.

2) Detect changes to files.

After copying the file, the backup application uses the operating system to check what changed during the copy operation. If there is a change, the copy is repeated, otherwise the file is skipped. Since many files (especially database files) continue to be used, the above two methods do not provide a proper solution. In addition, both methods exclude users during backups. In addition, there are few second storage devices and operating systems capable of maintaining a transfer rate of 15 megabytes (Mb) or more per minute, and it takes a long time to copy large files.

Some application programs solve this problem by using a secure backup method of their own files in a partitioned environment, but each process is different. To back up the entire storage, the backup application must know what each other configuration process is doing and rely on manual adjustments at the appropriate points. As such, the backup application must back up the entire file and the file must not be modified by another application program during the backup process, so that a conventional backup method is used to retreat to a computer system with partitioned storage means. This is especially true when backing up large files.

[Summary of invention]

According to a first aspect of the present invention, there is provided a method of operating a computer system based on a microprocessor including a RAM, a central processing unit and storage means; Providing a backup process that is executed in a computer system and is operable to perform at least one backup read operation that generates a start signal and a stop signal and reads original data from a storage means, causing the central processing unit to periodically read the data. The central processing of the first instruction stored in the memory to perform at least one normal writing operation to write to the basic area of the storage means and at least one normal reading operation to read data from the storage means; Providing to a device, interrupting the recording operation after receiving the start signal and performing a blocking operation of recording data in a second storage area of the storage means to preserve original data overwritten by the recording operation; Maintaining a record of said record for a second area, and Interrogating the record to read data from either the primary or second storage area in accordance with the record at the same time as performing any one of a previous backup and a normal read operation, whereby the start signal is generated. Provided is a method of operating a microprocessor-based computer system, wherein a backup process is provided to preserve original data in a previous state. Optionally, the second data may be recorded in the delta area and other applications may continue recording at the intended location on the storage device. The delta area is another area of the same storage device which may preferably be a hard disk, for example. Further operations for carrying out the invention are advantageously stored and operated at the operating system interface level of the computer system. If the software for performing the method of the present invention is stored at the operating system level, it is transparent so as not to affect the application software. As for the record, this includes a record of the first data, a record of the data intended to be located in storage, and a record of its actual location, the method further comprising obtaining a second data from the intended location. .

It is preferable that a start command be issued before the backup application program starts a backup, and a stop command is issued after the backup is completed. Such backup records may be stored in various storage means such as, for example, tape drives, optical disks, or in another basic storage medium area. Once backed up, it can be stored in the usual way.

According to a second aspect of the present invention, there is provided a method for supplying data to a backup process executed in a microprocessor-based computer system including a RAM, a central processing unit and a storage means, wherein the central processing unit periodically supplies the data. The central processing of the first instruction stored in the memory to perform at least one normal writing operation to write to the basic area of the storage means and at least one normal reading operation to read data from the storage means; Generating to a device, receiving a start signal from a backup process, interrupting the recording operation after receiving the start signal, and storing the original data overwritten by the recording operation in a second storage area of the storage means. Performing a blocking operation for recording data, wherein the recording of the second area is performed. Maintaining a record of the lock, and querying the record for reading data from either the primary or second storage area in accordance with the record while performing any of the backup and normal read operations. Thus, a data supply method for a backup process is provided, wherein a backup process is provided for preserving original data in a state before the start signal occurs.

According to a third aspect of the present invention, there is provided a microprocessor-based computer system including a RAM, a central processing unit, and a storage means, comprising: at least one backup generating a start signal and a stop signal and reading original data from the storage means. Means for executing a backup process operative to perform a read operation, at least one conventional write operation that causes the central processing unit to periodically write data to the basic area of the storage means and to read data from the storage means; Means for performing at least one normal read operation, means for receiving the start signal, and a second storage area of the storage means for storing original data overwritten by the write operation after receiving the start signal. To record data in and to said second area for Means for executing a blocking operation to block the recording operation to hold a record of the lock, and means for querying the record to read data from either the primary or the second storage area according to the record. The above provides an improvement of a computer system, wherein a backup process is provided that can carry out any one of the backup and normal read operations and at the same time save the original data in the state before the start signal occurred. .

[Description of Specific Example of the Invention]

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In FIG. 1, the personal computer 10 typically includes a central processing unit (CPU) 12, a RAM 14, and a nonvolatile storage device 16 in the form of a hard disk drive. In this example, the tape unit 18 is connected to the computer 10 to provide a backup storage means.

According to the present invention, in order to control the data flow between the disk drive 16 and other parts of the computer 10, the backup program application unit intercepts normal read and write operations from and to the disk drive 16. It consists of a recording process that operates.

Prior to starting a backup copy of a file, the write process is started by the backup application to transfer the entire disk write activity to another area of the disk 16, known as the ″ delta ″ area. The delta mapping table maintains the entire disk write operation transferred to the delta area. This table maintains a mapping between the data associated with each disk write operation and the intended destination on disk 16 at its actual storage location in the delta area. If a subsequent write operation is made in the area that is already the entry target of the table, the new data is overwritten on the old data in the delta area. In this way, the data on the main part of the disk does not change during the backup copy, so all changes are transferred to the delta area.

When a disk read operation is requested by the backup application, the data returned to the backup application passes through unchanged to be derived from the original data area of the main part of the disk. However, when a disc read operation is requested by another application, the write process first knows whether a disc write has occurred to that area because the process has begun blocking the write operation, and if so the read operation has been sent to the corresponding point in the delta area. It works by checking the table for viewing. If there is no write operation, i.e., that portion of the data has not changed because the write operation has been interrupted, then the read operation passes unchanged.

In this way, changes in the data stored on the disk 16 are monitored by all ordinary applications other than the backup application. The backup application monitors data that does not change until a command is issued to stop the write process, which blocks read and write operations.

When the backup copy operation ends, the recording process operates to restore the computer to its normal operating state. This recovery step can be accomplished by applying the changes stored in the delta area to the appropriate original data area of the disk 16's main part using the mapping stored in the table. While the delta change is applied, the disc recording operation continues to be interrupted as described above. When there is no longer a recording operation not applied to the original data area, blocking of the recording operation is stopped and the system is normally operated. If the record forming the second record from the delta mapping table is within the range where the backup copying process is taking place, it is no longer a problem if the data changes, so that after the part of the disc has been backed up, the software The recording operation for the main part passes without any change. In other words, upon receipt of a command for a write operation, the software determines from the second record whether the portion of the disc to be written is backed up by the backup process, and if this portion is a backup, the write operation is written to the disc without interruption. do.

This reduces the size of the delta mapping table. In addition, if the operation-oriented area in the main disk portion is already an entry target of the mapping table, the entry can be simply removed, thereby reducing the time required in the recovery step.

The present invention applies specifically to IBM compatible personal computers, i.e. most personal computers using chip type numbers 8086, 8088, 80286, 80386, 80486 and Pentium processors and similar microprocessor based systems manufactured by Intel. Can be. On such computers, whenever a program wants to access a file, it calls a standard routine that writes data to disk. This routine, known as Interrupt 21 hex (INT 21h) in the case of the DOS operating system, is an integral part of the operating system. The actions performed by this routine depend on the variables that pass from the entry to the routine. This routine is shown in FIG. 2 (a) as INT 21h constituting the operating system portion in the system memory map, and the INT 21h entry point is shown by an arrow. In order to carry out the above-described method according to the invention, additional program code must be added at the operating system interface level as shown in FIG. 2 (b). In practice, in a DOS environment, this is C0NFIG. It can be loaded into the computer as a device driver using the SYS file. The added software has the effect of commanding the recording of data to be replaced by an optional command set. Similar techniques may be used to intercept commands to read data from the disk and replace them with an optional command set.

In Figure 3, the relevant operating procedure is shown in a flowchart. On receiving an INT 21h call, the program first checks whether the call is a write call. If it is a call, the program checks in step 20 whether it is a blocked call. If not a blocked record call, the data is recorded in the original data area 24 (step 22).

If the call is blocked, the program checks the delta mapping table to see if the record has already been made in the original file area 24 (step 26). That is, the delta mapping table is queried to determine whether there is a previous blocked write operation involved in the recording of the data to be recorded on the same part of the disc as the current write operation. If the record is pre-determined at step 28, the portion of the delta area 30 already mapped to that part of the original file 24 in the delta mapping table is overwritten by the new material (step 32).

If the call is blocked but the record is not already made in that part of the original file 24, the record is added to the table and the data is written to the new delta area (step 36).

If the call is a read call, the program checks in step 38 whether it is a blocked read call. If it is not a blocked read call, the data is read from the original file 24 (step 40).

If it is a blocked read call, first it is checked whether the call is derived from a backup application program (step 42). If the call is from a backup application, the program proceeds to step 40 and reads data from the original file 24.

If the readout is not from a backup application, the program checks the delta mapping table to see if a record of the area of the original file 24 corresponding to that of the readout has been transferred to the delta area (step 44). If not (step 46), the program returns to step 40 and the data is read from the original file 24. If a read has been sent, the data is read at the calibration section of delta area 30 (step 48). In the second embodiment of the present invention, instead of storing the changed data in the delta area, if the read and write operations are interrupted during the recording process and the first recording is made in a special area of the file, the original material is stored in the delta area. Changes to the original file are made. An entry is made in the mapping table that points to the original contents of the original file area currently stored in the delta area. Any subsequent recording of the same area of the file is ignored by the recording process. If the mapping table points to an overwritten area of the original file, read requests from the backup application are sent to the delta area. 4 shows a flow diagram of a second embodiment of the present invention. The flowchart of FIG. 4 is similar to the flowchart of FIG. 3 and similar operations have been given the same reference numerals. The difference between FIG. 3 and FIG. 4 is as follows. At step 60, if read blocking is activated (step 38) and the read is not from a backup application, the data is read from the original data area. This is the reverse of step 42 in the preceding embodiment. First, an additional step 62 of reading data from the original data area prior to overwriting is added following step 28.

Step 36 in the first embodiment is transformed into a new step 64 in combination with further recording the material read in step 62 into the delta area. Step 32 in the first embodiment is transformed into a new step 66 where the data is written to the original data area instead of overwriting the delta area. The method according to the second embodiment is slower than the method according to the first embodiment because each file write request consists of one read and two writes as opposed to the single transfer record of the first method. to be. However, in the second method, once the backup is completed, the changes stored in the delta area are not required to be applied to the original file. Data stored in the delta mapping table and delta area can be removed simply. In addition, this difference eliminates the need to prepare for recovery from catastrophic conditions (eg, power failures) that occur when delta changes are not fully applied to the original data.

If the method described above constitutes a backup application section, blocking of the read application may occur between backup applications and there is no need to use an operating system routine.

If the computer conditions permit verification of a particular user who wishes to perform a backup, the present invention may include the step of recognizing the user and backing up only that user's files by the method described above. In this case, not all data transactions need to be blocked, only those relevant to that user.

Claims (19)

CLAIMS 1. A method of providing data to a backup process running a microprocessor-based computer system including RAM, central processing unit and storage means; Perform the at least one normal recording operation to cause the central processing unit to periodically write data to the basic area of the storage means and the at least one normal reading operation to read the data from the storage means. Issuing a first command stored in a memory to the central processing unit, receiving a start signal from a backup process, and interrupting the recording operation after receiving the start signal and overwriting the original data by the recording operation. Performing a blocking operation of recording data in a second storage area of the storage means to preserve the data, maintaining a first record of the recording for the second area, and any one of the backup and the normal read operation. Simultaneously sells data from either primary or secondary storage according to a record while doing one Wherein the first process is queried for reading, thereby providing a backup process for preserving original data in a state prior to the start signal being generated. Holding a second record indicating a degree, and upon receiving a command for a recording operation of the storage means, whether the portion of the basic area of the storage means to be recorded is backed up by the backup process; Determining from a record and if the portion is a backup, causing the recording operation to write to the basic area of the storage means without interruption. The recording medium of claim 1, wherein the data of a normal recording operation is recorded in the second area, and the first record is recorded in the second area and the record of the intended position for the normal recording operation in the basic area. And obtaining the preserved original material from the basic area, the record comprising a record of an actual location. The method of claim 2, wherein after receiving a stop signal from a backup process, at least one recovery read operation of reading data from the actual position in the second area according to the first record and the intended position in the basic area. Performing at least one recovery recording operation for restoring the data, and stopping the performing of the blocking operation for interrupting the recording operation when all the data is restored to its intended position in the basic area. Method comprising a. 2. The data to be stored is read from the basic area and recorded in the second area before the data by a normal recording operation is recorded in the basic area, and the record is preceded by the original material in the basic area. And a record for the position and a record for the actual position in the second area, the method further comprising obtaining original data stored from the actual position. 5. The method of claim 4, further comprising the step of stopping the blocking operation to interrupt the recording operation after receiving the stop signal from a backup process. 6. A method according to any one of claims 2 to 5, wherein said base area and said second area are different areas of a single memory device. The method of claim 1, wherein the command associated with the blocking operation is performed at a basic input / output system (BI0S) level. The method of claim 1, wherein the command associated with the blocking operation is performed at the operating system interface level. The method of claim 1, further comprising: providing a backup process for executing a computer system to generate a start signal and a stop signal to perform at least one backup read operation to enable operation of reading the original data from the storage means. How to feature. 10. The method of claim 9, wherein the start signal is generated before the backup process executes a backup operation in the storage device and a stop signal is generated after the backup process finishes the backup operation. The method of claim 1, further comprising deleting any entries related to the portion of the basic area of the storage means backed up by the backup process from the first record during the backup process and in response to another write command. Characterized in that the method. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and storage means; Providing a backup process to enable a computer system to generate at least a start signal, at least one conventional recording operation that causes the central processing unit to periodically record data in the basic storage area of the storage means; Issuing a first command stored in the memory to the central processing unit so as to perform an operation; and after receiving the start signal, perform a blocking operation to block the recording operation and to store the memory in the blocked recording operation. Recording the data to be recorded in the portion of the basic storage area of the storage means in the portion of the second storage area of the means and holding the record of the recording in the second storage area while holding the second memory in the portion of the basic storage area. In the above method in which a portion of the area is constituted by corresponding steps, the blocked recording operation is performed. The record is queried to determine whether there is a previous blocked recording operation involved in the recording of the data to be recorded in the portion of the basic memory area, such as the current blocked recording operation, and (a) if such a recording operation is present. Recording data previously recorded in the portion of the second storage area of the storage means in duplicate with new data in the previous blocked recording operation; and (b) if there is no such recording operation, in addition to the record; Recording data into the second memory area. 13. The method of claim 12, further comprising performing at least one recovery read operation to read data from the second area after receiving the stop signal and recovering the data to an intended location in the basic area according to the record. Performing one recovery write operation, and stopping performing the interruption operation that interrupts the recording operation when all data is restored to the intended position in the basic area. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and storage means; Providing a backup process to enable a computer system to generate at least a start signal, at least one conventional recording operation that causes the central processing unit to periodically record data in the basic storage area of the storage means; Issuing a first command stored in the memory to the central processing unit, and performing a blocking operation after receiving the start signal to block a recording operation and the storage means in the blocked recording operation. Prior to recording new data in the portion of the second memory area of the second memory area, the record of the record is read while reading the data in the portion of the basic memory area and writing to the portion of the second memory area of the storage means. The second memory area and the second memory area correspond to a portion of the basic memory area. In the above method, the blocked recording operation is configured to determine whether there is a previous blocked recording operation that is involved in the recording of data in the same portion of the basic storage area as the currently blocked recording operation. In question, (a) if there is such a recording operation, in the previous blocked recording operation, the data previously recorded in the basic storage area of the storage means is duplicated with new data; and (b) if such a recording operation is not present. And reading the data to be preserved from the basic memory area, recording the new data in the basic memory area in addition to the record. 15. The method of claim 14, further comprising: performing at least one recovery read operation to read data from the second area after receiving the stop signal and recovering the data to an intended location in the basic area according to the record. Performing one recovery write operation, and stopping performing the interruption operation that interrupts the recording operation when all data is restored to the intended position in the basic area. A microprocessor-based computer system including a RAM, a central processing unit and storage means; Means for executing a backup process operative to generate a start signal and a stop signal and to perform at least one backup read operation of reading the original data from said storage means, causing said central processing unit to periodically read data from said storage means; Means for performing at least one normal write operation to write to the area and at least one normal read operation to read data from the storage means, means for receiving the start signal, after receiving the start signal Intercepting the recording operation to record data in a second storage area of the storage means to preserve original data overwritten by the recording operation and to maintain a first record of the recording for the second area. Means for executing a blocking operation, and according to the first record Means for interrogating the first record to read data from either the present or second storage area, thereby performing the backup operation and preserving the original data in a state prior to the start signal being generated. A computer system provided with a backup process capable of receiving, the means operable after the start signal to maintain a second record indicating the extent to which the backup process proceeds, and the reception of a command for a recording operation of the storage means. At the second record determines whether or not a portion of the basic area of the storage means to be recorded is backed up by the backup process, and if the portion is a backup, the recording operation is blocked without interrupting the recording operation. A computer system characterized by means operable to record on a computer. 17. The backup process according to claim 16, wherein any entry relating to said portions backed up by said backup process as parts of said basic area of said storage means referred to by another write command is deleted during said backup process. And means operable in response to said another write command. An apparatus for operating a microprocessor-based computer system including an instruction memory central processing unit and storage means; Backup means operable to generate at least a start signal, and stored in the memory so that the augmentation processing apparatus can perform at least one normal recording operation to periodically record data in the basic storage area of the storage means; Means for issuing a first command to said central processing unit, and after receiving said start signal, to perform a blocking operation to block a recording operation and to record in a portion of said basic storage area of said storage means in this blocked recording operation. Means for recording one piece of data into a portion of the second storage area of said storage means and having a portion of said second storage area correspond to that of said basic storage area while maintaining a record of said record in said second storage area; In the apparatus, the blocking operation performing means is provided in the basic memory area such as the currently blocked recording operation. The record is queried to determine whether there is a previous blocked recording operation involved in the recording of the material to be recorded in the part, and (a) if such a recording operation is present, the storage means in the previous blocked recording operation. Means for recording the previously recorded data in duplicate in the second storage area with new data and (b) if there is no such recording operation, recording the new data in the second storage area in addition to the record. And further configured. An apparatus for operating a microprocessor-based computer system including an instruction memory, a central processing unit and storage means; Backup means operable to generate at least a start signal, and stored in the memory so that the central processing unit can perform at least one normal recording operation to periodically record data in the basic storage area of the storage means. Means for issuing a first command to the central processing unit, and after receiving the start signal, performs a blocking operation to block a recording operation, and in such a blocked recording operation, new data is added to a portion of the basic storage area of the storage means. The record of the record is advantageous to the second storage area and is part of the basic memory area while reading the data in the portion of the basic storage area prior to recording the data and recording the data in the portion of the second storage area of the storage means. In the apparatus comprising means for causing portions of the second storage area to correspond to, The performing means queries the record to determine whether there is a previous blocked recording operation that is involved in the recording of the material in the portion of the basic memory area such as the currently blocked recording operation, (a) If there is such a recording operation, the data previously recorded in the basic storage area of the storage means is duplicated with new data in the previous blocked recording operation, and (b) if there is no such recording operation, from the basic storage area. And means for reading out the data to be stored and recording it in a second storage area, and in addition to the record, recording the new data in the basic storage area.