TWI789984B - Method, system and computer-readable storage medium for synthetic incremental data backup - Google Patents

Abstract

A method for synthetic incremental data backup, a corresponding system and a corresponding computer-readable storage medium are provided. The method is executed by a data device and a backup device and includes: generating an incremental backup data and an incremental block change record (BCR) of an N-th backup according to a current data of the data device of an M-th backup and a current data of the data device of the N-th backup, wherein N is an integer greater than or equal to three and M is a positive integer less than N; generating a synthetic backup data and a synthetic BCR of the N-th backup according to a synthetic backup data and a synthetic BCR of the M-th backup and the incremental backup data and the incremental BCR of the N-th backup; and storing the synthetic backup data and the synthetic BCR of the N-th backup in the backup device.

Description

Synthetic incremental data backup method, system and computer-readable storage medium

The present invention relates to a data backup technology, and in particular to a synthetic incremental data backup method, system and computer-readable storage medium using full backup and incremental backup for composite backup.

With the advancement of data storage technology, the capacity of data storage devices such as hard disks continues to increase, and sometimes the storage space of the data storage device is divided into multiple data volumes for easy use and management, such as in Microsoft Windows (Windows) operating system can divide the storage space of a hard drive into multiple data volumes such as C slot, D slot and E slot, wherein each data volume includes multiple blocks (blocks) for storing data .

In order to avoid data damage caused by factors such as human error, virus damage, or hardware failure, users usually back up the data in the data volume on a regular basis. Currently commonly used data backup methods include full backup, incremental backup, and differential backup.

A full backup means that each backup sends all the used blocks in the data volume to the server that provides data backup services. When it is necessary to restore the data in the data volume, it can be obtained from the server Previously backed up data can be restored, but if it is necessary to store previous full backup data due to version control and other requirements, a large amount of storage space is required.

On the other hand, incremental backup only makes a full backup in the first backup, and in each subsequent backup, only the newly added and modified blocks after the previous backup are sent to the server without sending All used blocks. In this way, the storage space required for incremental backup is significantly smaller than that of full backup. However, incremental backup must store the data of previous backups, so that the backup history can be traced back to rebuild the data when the data needs to be restored. Therefore, if there is any backup in the backup history If the data is damaged, the data cannot be reconstructed, causing troubles during backup.

On the other hand, the differential backup only performs a full backup in the first backup, and in each subsequent backup, the newly added and modified blocks after the first full backup are sent to the server. Therefore, only the data of the first full backup and the data of the latest differential backup are needed to restore the data in the data volume, but the advantages and disadvantages of differential backup are between full backup and incremental backup.

In order to solve the above-mentioned problems, the present invention provides a method for synthesizing incremental data backup, which exists in a synthetic incremental data backup system composed of a data device and a backup device, including: the data device according to the Mth backup and the Nth backup The current data of the data device is incrementally backed up to generate the incremental backup data and incremental block change records of the Nth backup; the backup device is based on the synthetic block change records and the The incremental block change record of the Nth backup generates the synthetic block change record of the Nth backup; the backup device is based on the synthetic backup data of the Mth backup, the incremental backup of the Nth backup data, the synthetic block change record of the M-th backup, and the incremental block change record of the N-th backup, to generate the synthetic backup data of the N-th backup; And the synthetic incremental data backup system stores the synthetic backup data of the Nth backup and the synthetic block change record in the backup device.

The present invention also provides a computer-readable storage medium, which is used in a backup device and stores instructions to execute the above method for synthesizing incremental data backup.

The present invention also provides a synthetic incremental data backup system, including: a data device for performing incremental backups based on the current data of the data device in the M-time backup and the N-time backup, so as to generate the incremental data of the N-time backup Quantitative backup data and incremental block change records; and a backup device for storing the synthetic backup data and synthetic block change records of the Nth backup, wherein the synthetic block change records of the Nth backup are created by The backup device is generated according to the synthetic block change record of the M-time backup and the incremental block change record of the N-time backup, and the synthetic backup data of the N-time backup is generated by the backup device according to The synthetic backup data of the M-th backup, the incremental backup data of the N-th backup, the synthetic block change records of the M-th backup, and the incremental block change records of the N-th backup, producer.

The synthetic incremental data backup method and system provided by the present invention require less storage space than full backup, do not need to go back to the entire backup history to rebuild data like incremental backup, and are more efficient than differential backup.

10: Synthetic incremental data backup system

11: Data device

12: Backup device

30: Data volume

31: snapshot

32:Volume Bitmap

33: Block data

34: hash function

35: hash value table

B ₀ ~B ₆ : block

C-DATA _N : current data

F-DATA: complete backup data

I-BCR _N : incremental block change record

I-DATA _N : Incremental backup data

S-BCR _M , S-BCR _N : synthetic block change record

S-DATA _M , S-DATA _N : synthetic backup data

FIG. 1 is a block diagram of a synthetic incremental data backup system according to an embodiment of the present invention.

FIG. 2 is a schematic flowchart of a method for backing up synthetic incremental data according to an embodiment of the present invention.

FIG. 3 is a schematic flow chart of generating block hash values in the method for synthesizing incremental data backup in FIG. 2 .

FIG. 4 is a schematic diagram of an example of synthetic backup in the method for synthesizing incremental data backup in FIG. 2 .

FIG. 5 is a schematic diagram of deduplication of data in the synthetic incremental data backup method of FIG. 2 .

FIG. 6 and FIG. 7 are schematic diagrams of synthetic backup failures in the method for synthesizing incremental data backup in FIG. 2 .

8 to 10 are schematic diagrams of restoring data in the synthetic incremental data backup method of FIG. 2 .

FIG. 11 is a schematic diagram of an example of restoring data in the synthetic incremental data backup method of FIG. 2 .

The implementation of the present invention will be described below through specific specific examples. Those with ordinary knowledge in the technical field can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

1 is a block diagram of a synthetic incremental data backup system 10 according to an embodiment of the present invention. The synthetic incremental data backup system 10 includes a data device 11 and a backup device 12, wherein the data device 11 and the backup device 12 can be connected via a cable. Or connect to each other wirelessly to transmit data to each other.

In one embodiment, the data device 11 can be a smart phone, a computer, a server, or any other type of electronic device with data processing functions, and the backup device 12 can be a smart phone, a computer, a server, a network Additional storage device (network attached storage, NAS), or any other kind of electronic device with data storage function.

In one embodiment, the data device 11 includes at least one data storage device, and the at least one data storage device includes at least one data volume, such as a data volume of Microsoft's Windows operating system, the data volume includes a plurality of blocks, and the backup The device 12 can provide data backup and restoration services for the data volume.

FIG. 2 is a schematic flow chart of a method for synthesizing incremental data backup according to an embodiment of the present invention. The method for synthesizing incremental data backup can be composed of the data device 11 and the backup device 12 of the synthetic incremental data backup system 10 shown in FIG. 1 Cooperative execution.

First, during the first backup, the data device 11 fully backs up the current data in the data volume. The current data is a collection of all used blocks in the data volume. The full backup is to combine all the used blocks in the data volume into a complete backup data, and then send the complete backup data to the backup device 12. The backup device 12 receives the full backup data from the data device 11 to store the full backup data in the backup device 12 .

Then, during the second backup, the data device 11 performs incremental backup on the current data in the data volume to generate the incremental backup data I-DATA ₂ and the incremental block change record I-BCR for the second backup _2. Send the incremental backup data I-DATA ₂ and the incremental block change record I-BCR ₂ of the second backup to the backup device 12.

The incremental block change record I-BCR ₂ of the second backup is compared with the hash value of each block in the current data of the first backup and the hash value of each block in the current data of the second backup. Generated (details will be described later), and the incremental block change record I-BCR ₂ of the second backup includes changes such as addition, modification, and deletion of blocks in the data volume from the first backup to the second backup Record.

The incremental backup data I-DATA ₂ of the second backup includes all new blocks and all modified blocks in the incremental block change record I-BCR ₂ of the second backup, in other words, I-DATA ₂ includes All new blocks and all modified blocks from the first backup to the second backup.

The backup device 12 receives the incremental backup data I-DATA ₂ and the incremental block change record I-BCR ₂ of the second backup from the data device 11, so that the incremental backup data I-DATA ₂ of the second backup and the incremental The block change record I-BCR ₂ is directly used as the synthetic backup data S-DATA ₂ of the second backup and the synthetic block change record S-BCR ₂ , and then the synthetic backup data S-DATA ₂ of the second backup is combined with The composite block change record S-BCR ₂ is stored in the backup device 12 .

FIG. 3 is a schematic flow chart of generating block hash values in the method for synthesizing incremental data backup in FIG. 2 . During each backup, the data device 11 can generate the hash value of each block of the current data in the data volume 30 according to this process.

First, a snapshot 31 of the data volume 30 is generated. The snapshot 31 can also be called a shadow copy.

Next, a volume bitmap 32 of the data volume 30 is read from the snapshot 31 . Each block of the data volume 30 corresponds to a bit in the volume bitmap 32, and the bit indicates whether the corresponding block is used or unused.

Next, read the data 33 of all used blocks in the data volume 30 according to the volume bitmap 32 . In an embodiment as shown in FIG. 3 , the volume bitmap 32 indicates that the blocks B ₀ , B ₂ and B ₅ have been used, so the data 33 of the blocks B ₀ , B ₂ and B ₅ are read and unused. The block does not need to be read.

Next, use a preset hash function (hash function, such as SHA-256) 34 to calculate the hash value (hash value) of the data 33 of each used block in the data volume 30 to generate a hash value table (hash directory) 35 . The hash value table 35 includes the serial number of each block in the current data and the hash value of the data. For example, as shown in FIG. 3 , the hash value of the data in block B ₀ is c6c5876 (hexadecimal), and so on.

The data device 11 generates and stores a hash value table of the current data during each backup. During each backup, the data device 11 compares the hash value table of this backup with the previous backup, and can know which blocks in the data volume 30 have been added, modified or deleted between the two backups, so as to Generate the incremental block change records for this backup.

Then, please refer to FIG. 2 and FIG. 4 together. During the third backup and each subsequent backup (hereinafter referred to as the Nth backup, N is an integer greater than or equal to three), the data device 11 Increment the current data of M backups (M is a positive integer less than N, if the latest backup before the Nth backup has no data damage, then M is equal to N-1) and the current data of the Nth backup Backup to generate incremental backup data I-DATA _N and incremental block change records I-BCR _N for the Nth backup, and then change the incremental backup data I-DATA _N and incremental blocks for the Nth backup The record I- _BCRN is sent to the backup device 12 .

The incremental block change record I-BCR _N of the Nth backup is compared with the hash value of each block in the current data of the Mth backup and the hash value of each block in the current data of the Nth backup. Generated, and the incremental block change record I-BCR _N of the Nth backup includes change records such as addition, modification, and deletion of blocks in the data volume 30 from the Mth backup to the Nth backup.

The incremental backup data I-DATA _N of the Nth backup includes all newly added blocks and all modified blocks in the incremental block change record I-BCR _N of the Nth backup.

Next, the backup device 12 receives the incremental backup data I-DATA _N and the incremental block change record I- _BCRN of the Nth backup from the data device 11, and performs synthetic backup. The synthetic backup is based on the synthetic block change record S-BCR _M of the M backup and the incremental block change record I-BCR _N of the N backup to generate the synthetic block change record S-BCR _N of the N backup , and according to the synthetic backup data S-DATA _M of the Mth backup, the incremental backup data I-DATA _N of the Nth backup, the synthetic block change record S- _BCRM of the Mth backup, and the Nth backup Incremental block change record I- _BCRN to generate the synthetic backup data S-DATA _N of the Nth backup, and then store S-DATA _N and S- _BCRN in the backup device 12 . The present invention does not limit the _relative order of generating S-DATA _N and S-BCR _N. In different embodiments, the backup device 12 may first generate S-DATA _N and then generate S-BCRN, or generate S-BCR _N first and then generate S-DATA _N.

The composite block change record S-BCR _M of the Mth backup includes the blocks in the data volume 30 of the data device 11 from the previous full backup (for example, the first backup in this embodiment) to the Mth backup Addition, modification, deletion and other change records. In an embodiment as shown in FIG. 4 , the S- _BCRM records that blocks B ₀ and B ₁ are added, and blocks B ₂ and B ₃ are modified during the period from the previous full backup to the M-th backup.

The incremental block change record I-BCR _N of the Nth backup includes change records such as addition, modification, and deletion of blocks in the data volume 30 from the Mth backup to the Nth backup. In one embodiment as shown in Figure 4, the I-BCR _N record is from the Mth backup to the Nth backup period, block _B4 is added, block _B0 is modified, and block _B2 is delete.

The synthetic block change record S-BCR _N of the Nth backup is obtained by merging the incremental block change record I-BCR _N of the Nth backup into the synthetic block change record S-BCR _M of the Mth backup Block change record, therefore, the synthetic block change record S-BCR _N of the Nth backup includes change records such as addition, modification, and deletion of blocks in the data volume 30 from the previous full backup to the Nth backup. In an embodiment as shown in FIG. 4 , the S-BCR _N records that blocks B ₀ , B ₁ and B ₄ are added, block B ₃ is modified, and Block B ₂ is deleted.

The synthetic backup data S-DATA _N of the Nth _backup includes all new blocks and all modified blocks in the synthetic block change record S-BCR _N of the Nth backup. All new blocks and all modified blocks between the full backup and the Nth backup. In one embodiment shown in Figure 4, S-DATA _N includes newly added blocks B ₀ , B ₁ , B ₄ and modified blocks B ₃ recorded by S-BCR _N , wherein, blocks B ₁ and B ₃ is from S-DATA _M , and blocks B ₀ and B ₄ are from I-DATA _N .

As can be seen from Figure 4, the generation rules of S-DATA _N , in detail, for each block recorded as new or modified in S-BCR _N , if I-DATA _N includes this block, then from I-DATA N DATA _N copies the block to S-DATA _N , otherwise copies the block from S-DATA _M to S-DATA _N . In addition, for the blocks recorded as deleted in S- _BCRN , these blocks are not copied to S-DATA _N .

After each backup, the backup device 12 can deduplicate the complete backup data and the composite backup data stored in the backup device 12 during previous backups to save storage space. In an embodiment as shown in FIG. 5 , the synthetic backup data S-DATA _N generated by the backup device 12 during the N-time backup includes blocks B ₀ -B ₃ . Before the N+1th backup, the block B ₀ is deleted, so the synthetic backup data S-DATA _N+1 generated by the backup device 12 during the N+1th backup only includes blocks B ₁ -B ₃ . Before the N+2th backup, the block _B1 is deleted, so the synthetic backup data S-DATA _N+2 generated by the backup device 12 during the N+2th backup only includes the blocks _B2 and _B3 . In order to store the synthetic backup data of these three backups, the storage device 12 needs to store one block B ₀ , two blocks B ₁ , three blocks B ₂ and three blocks B ₃ , and a total of 9 blocks are required. storage space.

After the data is deduplicated, only one copy of each block B ₀ -B ₃ needs to be stored. For example, the backup device 12 only stores the blocks B ₀ ~ B ₃ of S-DATA _N , and the blocks B 1 ~ B 3 of S-DATA _N+1 can be respectively used to point to the blocks _{B 1 ~ B 3 of} S-DATA _N The index of the block B ₂ and B ₃ of S-DATA _N+2 can also be replaced by the index pointing to the block B ₂ and B ₃ of S-DATA _N respectively, so that a total of only 4 blocks are needed The storage space can greatly reduce the storage space requirement of the backup device 12 .

In addition, if the hash value table of a certain backup stored in the data device 11 is accidentally damaged and the next backup cannot be performed, or the complete backup data or synthetic backup data of the backup stored in the backup device 12 is caused by accidental damage. If the next backup cannot be performed and the current data of the data device 11 cannot be restored, the backup can be called a failure. On the contrary, if the above-mentioned data damage does not occur, the backup can be called successful. For unexpected events of backup failure, there are the following two optional handling methods.

The first processing method is to perform a full backup at the next backup of the failed backup. For example, as shown in Figure 6, the N+1th backup fails. Carry out a complete backup, as shown in Figure 2 for the first backup, the subsequent N+3th and N+4th backups are respectively like the second and third backups shown in Figure 2, and so on.

The second processing method is that when the current backup fails, the complete backup data or synthetic backup data of the previous backup is not used for synthetic backup, but the complete backup data or synthetic backup data of the last successful backup is used for synthetic backup. For example, as shown in Figure 7, the N+1th backup failed. Therefore, during the N+2th backup, the synthetic backup of the N+1th backup is not used for synthetic backup, but the synthetic backup of the Nth backup The data is backed up synthetically. To give another example, in the example in Figure 4, if no data damage occurs in the N-1th backup, then the M-th backup in Figure 4 is the N-1th backup, otherwise, the M-th backup is the Nth The last successful backup before the last backup, that is, the latest backup without data corruption.

Next, please refer to FIG. 8 to FIG. 10 , which are schematic diagrams of restoring data in the method for synthesizing incremental data backup in FIG. 2 .

When it is necessary to restore the current data of the data device 11 backed up for the first time, as shown in FIG. Current material in Volume 30.

When it is necessary to restore the current data of the data device 11 backed up for the second time, as shown in FIG. , restore the current data backed up for the second time, and then send the current data backed up for the second time to the data device 11 for the data device 11 to restore the current data in its data volume 30 .

When it is necessary to restore the current data of the data device 11 backed up for the third time, as shown in FIG. , restore the current data backed up for the third time, and then send the current data backed up for the third time to the data device 11 for the data device 11 to restore the current data in its data volume 30 .

In view of the importance of the complete backup data, in one embodiment, the backup device 12 can copy the complete backup data into at least two copies and store them in the backup device 12 during the first backup. When it is necessary to restore the current data of the data device 11 in a subsequent backup, the backup device 12 first checks whether the complete backup data is damaged, and then restores the current data of the backup according to one of the undamaged complete backup data .

Please refer to FIG. 11 , which is a schematic diagram of an example of restoring data in the synthetic incremental data backup method in FIG. 2 , and the example in FIG. 11 corresponds to the example in FIG. 4 . As shown in Figure 11, when it is necessary to restore the current data C-DATA _N of the data device 11 backed up for the Nth time (N is an integer greater than or equal to three), the backup device 12 is based on the complete backup data F-DATA N of the first backup. DATA, and the synthetic backup data S-DATA _N of the Nth backup and the synthetic block change record S-BCR _N to restore the current data C- DATA _N of the Nth backup, and then restore the current data C of the Nth backup - DATA _N is sent to the data device 11 for the data device 11 to restore the current data in its data volume 30 .

It can be seen from Figure 11 that the generation rules of C-DATA _N , in detail, is to copy the block recorded as new or modified in S-BCR _N from S-DATA _N to C-DATA _N , and will exist in Blocks in F-DATA that do not exist in S-DATA _N and are not recorded as deleted in S-BCR _N are copied from F-DATA to C-DATA _N . That is, for the blocks recorded as deleted in S- _BCRN , these blocks are not copied to C-DATA _N . In the embodiment shown in Figure 11, blocks B ₀ , B ₁ , B ₃ and B ₄ in C-DATA _N are from S-DATA _N , and blocks B ₅ and B ₆ in C-DATA _N are from F-DATA.

The present invention is not limited to the above-mentioned synthetic incremental data backup system and method. In one embodiment, the present invention also provides a computer-readable storage medium, such as a memory, a floppy disk, a hard disk or an optical disk. The computer-readable storage medium can be used in the backup device 12 and stores instructions to make the backup device 12 execute the above method for synthesizing incremental data backup.

In summary, the synthetic incremental data backup method, system, and computer-readable storage medium of the present invention only need to store the newly added or modified blocks after the first full backup, and therefore Requires less storage space than traditional full backups.

In addition, when the synthetic incremental data backup method, system and computer-readable storage medium of the present invention restore the current data of a certain backup, only the complete backup data of the first backup and the synthetic backup data of the backup are needed, that is The current data of the backup can be reconstructed without going back to the entire backup history to reconstruct the current data, so it has higher efficiency and fault tolerance than traditional incremental backup.

Furthermore, the synthetic incremental data backup method, system, and computer-readable storage medium of the present invention only need to take out the difference data from the last full backup or incremental backup, and do not need to take out the difference data from the previous full backup. Take out, so the amount of data taken out will be much smaller than the differential backup, the present invention is different In differential backup, incremental backup is performed based on the data difference between the first full backup and this backup, so the synthetic incremental data backup method of the present invention is more efficient than traditional differential backup.

In addition, the synthetic incremental data backup method, system and computer-readable storage medium of the present invention adopt block-level data backup and restoration, so its performance is better than traditional file-level data backup and restoration.

Furthermore, the synthetic incremental data backup method, system and computer-readable storage medium of the present invention can achieve application-consistent backup through the Volume Shadow Copy Service of the Windows operating system. In other words, the synthetic incremental data backup method, system and computer-readable storage medium of the present invention can freeze the disk operation of the application program during backup, and then perform data backup to ensure that the application program can continue to execute normally after the data is restored , thus outperforming traditional crash-consistent backups.

The above-mentioned embodiments are only illustrative to illustrate the principles and effects of the present invention, and are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the rights of the present invention should be listed in the scope of the patent application described later.

10: Synthetic incremental data backup system

11: Data device

12: Backup device

Claims (11)

A synthetic incremental data backup method, realized by a synthetic incremental data backup system composed of a data device and a backup device, comprising: the current data of the data device backed up by the data device according to the Mth time and the Nth time Incremental backup is performed on the current data of the data device to be backed up to generate incremental backup data and incremental block change records of the Nth backup, wherein, N is an integer greater than or equal to three, and M is a positive number less than N Integer, and the Mth backup is the latest backup without data damage before the Nth backup; the backup device changes the record according to the synthetic block of the Mth backup and the incremental area of the Nth backup A block change record generates a synthetic block change record of the Nth backup, wherein the synthetic block change record of the Mth backup includes blocks in a data volume of the data device from the previous full backup to the The change record of the M backup, the incremental block change record of the N backup includes the change record of the block in the data volume from the M backup to the N backup, and the N backup The synthetic block change record of the backup includes the change record of the blocks in the data volume from the previous full backup to the Nth backup; the incremental backup data of the second backup, the synthetic block change record of the M-th backup, and the incremental block change record of the N-th backup to generate the synthetic backup data of the N-th backup; and The synthetic incremental data backup system stores the synthetic backup data and the synthetic block change record of the Nth backup in the backup device. The method for synthesizing incremental data backup as described in claim 1, wherein, the incremental block change record of the Nth backup is compared with the hash value of each block in the current data of the Mth backup and the The hash value of each block in the current data of the Nth backup is generated, and the Nth backup The incremental backup data includes all newly added blocks and all modified blocks in the incremental block change record of the Nth backup. The method for synthesizing incremental data backup as described in Claim 1 further includes: the backup device receives the full backup data of the previous full backup from the data device, so as to store the full backup data in the backup device, wherein, The full backup data includes all used blocks in the data volume of the data device of the previous full backup. The method for synthesizing incremental data backup as described in claim item 3 further includes: receiving the incremental backup data and incremental block change records of the next backup of the previous full backup by the backup device from the data device, so as to The incremental backup data and the incremental block change record of the next backup are directly used as the synthetic backup data and the synthetic block change record of the next backup, and then stored in the backup device. The synthetic incremental data backup method as described in claim 3 further includes: the backup device deduplicates the full backup data and the synthetic backup data stored in the backup device during previous backups. The synthetic incremental data backup method as described in Claim 3 further includes: the backup device restores the N-th backup data according to the complete backup data, the synthetic backup data of the N-th backup, and the synthetic block change record the current data of the Nth backup; and the current data of the Nth backup is sent to the data device by the backup device. The synthetic incremental data backup method as described in Claim 3 further includes: copying the complete backup data into at least two copies of data by the backup device, so as to store the at least two copies of data in the backup device; Restoring the current data of the Nth backup by the backup device according to the undamaged one of the at least two copies of data; and sending the current data of the Nth backup to the data device by the backup device. A computer-readable storage medium stores instructions, and the instructions are read by the data device and the backup device to execute the synthetic incremental data backup method described in any one of claims 1 to 7. A synthetic incremental data backup system, comprising: a data device, used to perform incremental backup according to the current data of the data device backed up for the Mth time and the current data of the data device for the Nth time backup, to generate the Nth time Incremental backup data and incremental block change records of the backup, where N is an integer greater than or equal to three, M is a positive integer less than N, and the Mth backup is the last time there is no data before the Nth backup a damaged backup; and a backup device used to store the synthetic backup data and synthetic block change records of the Nth backup, wherein the synthetic block change records of the Nth backup are generated by the backup device according to the Mth generated from the synthetic block change record of the second backup and the incremental block change record of the N-th backup, the synthetic block change record of the M-th backup includes blocks in a data volume of the data device Change records from the last full backup to the M-th backup, the incremental block change records of the N-th backup include blocks in the data volume from the M-th backup to the N-th backup Change record, the synthetic block change record of the Nth backup includes the change record of the block in the data volume from the previous full backup to the Nth backup, and the synthetic backup data of the Nth backup It is based on the synthetic backup data of the M-th backup, the incremental backup data of the N-th backup, the synthetic block change record of the M-th backup, and the incremental backup of the N-th backup by the backup device. Generated by volume block change records. Synthetic incremental data backup system as described in claim 9, wherein, the incremental block change record of the Nth backup is compared with the hash value of each block in the current data of the Mth backup and the Generated by the hash value of each block in the current data of the Nth backup, and the incremental backup data of the Nth backup includes all newly added areas in the incremental block change record of the Nth backup block and all modified blocks. The composite incremental data backup system as described in Claim 9, wherein, after the backup device receives the full backup data of the previous full backup from the data device, the full backup data is stored in the backup device, wherein the full The backup data includes all used blocks in the data volume of the data device of the last full backup.

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