WO2017113059A1 - Discrepant data backup method, storage system and discrepant data backup device - Google Patents

Abstract

A discrepant data backup method, storage system and discrepant data backup device, wherein the discrepant data backup method comprises: modifying a bit map according to a log record within a backup cycle; acquiring, on completion of the backup cycle, discrepant data according to the modified discrepant data bit map, and backing up the discrepant data. The present invention enables the rapid location of discrepant data as well as efficient data backup.

Description

Differential data backup method, storage system and differential data backup device Technical field

Embodiments of the present invention relate to the field of storage technologies, and in particular, to a differential data backup method, a storage system, and a difference bitmap backup device.

Background technique

Data is a key asset of modern enterprises. Providing fast and convenient protection of data is a basic task in daily work. Data backup is a guarantee of data protection. In order to reduce backup time, reducing the amount of data backed up is a good choice. An incremental backup is a solution that backs up only the data that has changed since the last backup, and does not back up the data that has already been backed up. Normally, the changed data block can be obtained by comparing the fingerprint of the data block. The fingerprint of a data block refers to the hash value of the data block. When the backup software first backs up, it calculates the hash value of each data block and saves it. At the next backup, the hash value of the read data block is calculated, and the hash value is compared with the hash value of the saved data block at the corresponding position. If they are the same, then this data block has no changes and no backup is required. If it is different, it means that this data block has changed since the last backup and needs to be backed up. In this way, it is possible to find out the changed data blocks. However, each backup must read each data block, and compare them in sequence, even if there is no change, the data block needs to be read, which increases the computational burden of the backup software, making the backup efficiency low.

Summary of the invention

The embodiment of the invention provides a differential data backup method, a storage system and a difference data backup device, which can modify the bitmap according to the log information in a backup period, thereby quickly finding the difference data in a backup period and improving the backup efficiency.

The first aspect of the embodiment provides a differential data backup method. The method is applied to a storage system including a processor, a memory, a production volume, and a target volume. Wherein, the production volume includes a plurality of data blocks having the same size, and each data block is allocated a continuous logical address. A bitmap is stored in the memory, the bitmap includes a plurality of bytes, each byte includes 8 bits, and each bit in the bitmap corresponds to one of the production volumes. The processor acquires a log record within a backup period, the log record including a start address of a data block to be written to the production volume and a length of the data block. Then, the processor determines, according to the start address and the length, and a logical address corresponding to each byte, a target byte corresponding to the data block in the bitmap. Determining, according to the start address and the length, and the size of the data block, the number of bits to be modified in the bitmap, n<0<=8, and according to the start address, the data The size of the block and the number of bits 8 included in each byte determine the start bit p in the bit to be modified, 0 = < p < 8. By the n, the p, and the formula

The processor calculates a target value, and reads a source value saved in the target byte, performs a bit or operation on the target value and the source value, and writes a value obtained after performing the bit or operation The target byte is entered to modify the bitmap. Upon determining that the backup period arrives, the processor obtains difference data according to the modified bitmap, and backs up the difference data to the target volume.

The first aspect of the present embodiment provides a specific manner of modifying a bitmap, which can modify a bitmap according to log information in a backup period, thereby quickly finding the difference data in a backup period and backing it up to the target volume. Improve backup efficiency.

In conjunction with the first aspect, in a first implementation of the first aspect, the log record is generated by combining at least two write data requests, the logical addresses of the data blocks included in the at least two write data requests being consecutive or repeated. If the bitmap is modified according to two write data requests respectively, the bitmap needs to be modified at least twice, but it is merged into one log record, and the merged log record can be operated only once for the bitmap. , which improves the efficiency of modifying bitmaps.

In conjunction with the first aspect, in a second implementation of the first aspect, the log record is generated by combining at least one write data request and at least one delete data request, the write data request includes a logical address of the data block, and The logical address portion of the data block included in the delete data request is repeated. The effect achieved by the second embodiment is similar to that of the first embodiment, if the writing is separately described The data request and the delete data request modify the bitmap, then the bitmap needs to be modified at least twice, but after merging it into one log record, the modification of the partial bitmap can be offset, and only The bitmap operation is performed once, which improves the efficiency of modifying the bitmap.

In combination with any of the above embodiments, in a second implementation of the first aspect, the processor clears each bit of the bitmap after backing up the difference data into the target volume . Thus, the bitmap can continue to record modified data blocks in the next backup cycle.

The second aspect of the embodiment provides another differential data backup method. The method is applied to a storage system including a processor, a memory, a production volume, and a target volume. Wherein, the production volume includes a plurality of data blocks having the same size, and each data block is allocated a continuous logical address. A bitmap is stored in the memory, the bitmap includes a plurality of bytes, each byte includes 8 bits, and each bit in the bitmap corresponds to one of the production volumes. The processor acquires a log record within a backup period, the log record including a start address of a data block to be written to the production volume and a length of the data block. Then, the processor determines, according to the start address and the length, and a logical address corresponding to each byte, a target byte corresponding to the data block in the bitmap. Determining, according to the start address and the length, and the size of the data block, the number of bits to be modified in the bitmap, n<0<=8, and according to the start address, the data The size of the block and the number of bits 8 included in each byte determine the start bit p in the bit to be modified, 0 = < p < 8. The processor uses the n as the abscissa, and the p is the ordinate to search for a target value in a preset two-dimensional mapping table, and each value a _np in the two-dimensional mapping table is determined by a formula

Calculated. The processor continues to read the source value stored in the target byte, performs a bit or operation on the target value and the source value, and writes the value obtained after performing the bit or operation to the target word Section to modify the bitmap. Upon determining that the backup period arrives, the processor obtains difference data according to the modified bitmap, and backs up the difference data to the target volume.

The difference data provided by the second aspect is compared with the differential data backup method provided by the first aspect. The method uses a look-up table to obtain the target value. And each value in the two-dimensional mapping table is calculated by the formula provided by the first aspect, and is pre-stored in the storage system in the form of a table. Then, when the processor needs to obtain the target value, the n can be directly used as the abscissa, and the p is the ordinate in the preset two-dimensional mapping table. Thereby, the amount of calculation of the processor is reduced. Compared with the first aspect, the differential data backup method provided by the second aspect is more efficient in modifying the bitmap.

Various embodiments of the second aspect provided by the embodiments of the present invention are similar to the embodiments of the first aspect.

A third aspect of the embodiments of the present invention provides a storage system for performing the differential data backup method provided by the first aspect.

A fourth aspect of the embodiments of the present invention provides another storage system for performing the differential data backup method provided by the second aspect.

A fifth aspect of the embodiments of the present invention provides a differential data backup apparatus for performing the differential data backup method provided by the first aspect.

A sixth aspect of the embodiments of the present invention provides a differential data backup apparatus, configured to perform the differential data backup method provided by the second aspect.

The storage system or the differential data backup apparatus provided in the third to sixth aspects of the embodiments of the present invention can modify the bitmap according to the log information in one backup period, thereby quickly finding the difference data in one backup period and backing it up to the target volume. Improved backup efficiency.

The embodiment of the invention further provides a computer program product, comprising a computer readable storage medium storing program code, the program code comprising instructions executable by the storage system of the third aspect, and for performing the first aspect At least one method.

The embodiment of the invention further provides a computer program product, comprising a computer readable storage medium storing program code, the program code comprising instructions executable by the storage system of the fourth aspect, and for performing the second aspect At least one method.

The above computer program product provided by the embodiment of the present invention can all be based on a backup week During the period, the log information is modified to quickly find the difference data in a backup period and back it up to the target volume, which improves the backup efficiency.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the prior art or the embodiments will be briefly described below. Obviously, the drawings in the following description are only some implementations of the present invention. For example, other drawings may be obtained from those of ordinary skill in the art in light of the inventive work.

FIG. 1 is a schematic diagram of an application scenario according to an embodiment of the present invention;

2 is another application scenario diagram provided by an embodiment of the present invention;

3 is a structural diagram of a storage system according to an embodiment of the present invention;

4A is a schematic diagram of a bitmap provided by an embodiment of the present invention;

4B is a schematic diagram of another bitmap provided by an embodiment of the present invention;

4C is a schematic diagram of still another bitmap provided by an embodiment of the present invention;

FIG. 5 is a schematic flowchart of a differential data backup method according to an embodiment of the present invention;

FIG. 6 is a structural diagram of a differential data backup apparatus according to an embodiment of the present invention.

detailed description

The embodiment of the invention provides a differential data backup method and a storage system, which can quickly modify the bitmap to find the difference data in a backup period.

The application scenario of the embodiment of the present invention is introduced below.

As shown in FIG. 1, FIG. 1 depicts a composition diagram of a storage system 10 according to an embodiment of the present invention. The storage system 10 shown in FIG. 1 includes one or more hosts 40 and a storage device 20. The host can be a computing device, such as a terminal device such as a server or a desktop computer. The storage device 20 may be a storage device based on data block data, such as a Storage Area Networking (SAN) device, or a storage device including a file system, such as a Network Attached Storage (NAS) device. This embodiment does not limit the type of the storage device. A network file can be passed between the host 40 and the storage device 20, and between the storage devices 20 The system (Network File System, NFS)/Common Internet File System (CIFS) protocol or Fibre Channel (FC) protocol communicates.

The storage device 20 includes at least one controller 21 and a plurality of disks 22. Controller 21 can include any computing device such as a server, desktop computer, or the like. Inside the controller, an operating system and other applications are installed. The controller 21 can send an input/output (I/O) request to the disk 22. For example, a write data request is sent to the disk 22 such that the disk 22 writes the data to be written carried in the write data request into its storage medium.

The disk 22 can be a plurality of types of disks, such as Solid State Drive (SSD) or Serial Attached SCSI (SAS) or Fibre Channel (FC) hard disk drives (Hard Disk Drive, HDD). ), where SCSI (Small Computer System Interface) is the abbreviation of the minicomputer system interface or Serial Advanced Technology Attachment (SATA) or Near Line (NL) Serial Attached SCSI (Serial Attached SCSI) , SAS) HDD, not limited here. A logical unit (LU) is a logical storage space distributed over one or more disks 22, such as production volume 23 and target volume 24 shown in FIG. The host 40 can send a write data request to the storage system 10, the write data request carrying data to be written to the storage system 10, the data can be block data or a file. The controller 21 receives the data and then writes it into the logical unit of the storage device 20. In practical applications, in order to ensure data reliability, data needs to be backed up. For example, the data in the production volume 23 is backed up to the target volume 24. When the data in the production volume 23 is damaged, the data stored in the target volume 24 can be used for recovery.

The embodiment of the present invention is also applicable to another application scenario, as shown in FIG. 2 . 2 depicts a composition diagram of another storage system 10 that includes one or more hosts 40, a storage device 20, and a storage device 30. The storage device 30 is similar to the storage device 20 and includes at least one controller 31 and a plurality of disks 32. The structure and function of the controller 31 are similar to those of the controller 21 of FIG. 1. The structure and function of the magnetic disk 32 are similar to those of the magnetic disk 22 of FIG. 1, and will not be described herein. The difference from the application scenario described in FIG. 1 is that the backup in FIG. 1 refers to a storage device. Backup, while the backup in Figure 2 refers to a backup between two storage devices. For example, storage device 20 needs to back up data on its production volume to target volume 33 of storage device 30.

Regardless of the application scenario shown in FIG. 1 or the application scenario shown in FIG. 2, the controller 21 may use data when backing up data in one LU (referred to as a production volume) to another LU (referred to as a target volume). The method of full backup can also adopt the method of incremental backup.

A full backup is a full backup of all the data on the production volume. An incremental backup is data that has been modified since the last full or incremental backup, whichever is later. Because it is limited to backing up modified data (also known as differential data), this backup is very fast and saves storage space. So how to get the difference data becomes a problem that must be solved. In this embodiment, the difference data is obtained by recording a bitmap. This part will be described in detail in the following pages.

The composition of the controller 21 will be described below. As shown in FIG. 3, FIG. 3 depicts a composition diagram of the controller 21 provided by the embodiment of the present invention.

The controller 21 includes at least an interface 211, a processor 212, and a memory 213.

The interface 211 is configured to communicate with the host 40 or the disk 22 or the storage device 30.

The processor 212 may be a central processing unit CPU, or an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The processor 212 can be used to process input/output (I/O) requests to the disk 22, back up data in the production volume to the target volume, and the like. Thereby, the controller 21 can implement functions such as IO operation, data backup, and the like. In the embodiment of the present invention, the processor 212 is configured to execute the program 214, and specifically, the related steps in the following method embodiments may be performed.

The memory 213 is configured to store the program 214. The memory 213 may include a cache memory, may also include a high speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory. It can be understood that the memory 213 can be a random memory (RAM), a magnetic disk, a hard disk, a solid state disk (SSD), or a non-volatile memory. A non-transitory machine readable medium of code. The memory 213 can also be used to cache data received from the host 40 or data read from the disk 22.

Program 214 can include an operating system, a file system, and other software modules.

In the embodiment of the present invention, the bitmap may be generated or modified directly according to the IO request, because the IO request also carries the starting address of the data block and the length of the data block. When modifying a bitmap in this way, each time an IO request is received, the bitmap needs to be processed for that IO request. Even if in some cases multiple IO requests are operations on the same data block, only the last IO request is actually useful information for modifying the bitmap, but it must also be based on the information recorded by other IO requests. Modifications can cause unnecessary overhead in the generation of bitmaps.

In this embodiment, when the bitmap is generated or modified according to the log record, the log record may be sorted in advance. For example, if multiple log records are write operations for the same data block, these log records can be merged, and the corresponding portion of the data block in the bitmap is modified according to the merged result. Alternatively, if multiple log records are write operations for consecutive data blocks of several addresses, the log records may also be merged, and the multiple data blocks may be modified in a bitmap according to the combined result. part.

In this embodiment, the storage space in the disk 22 can be logically divided into a plurality of data blocks, each of which corresponds to a continuous logical address. The size of each data block is 512 bytes to 64 KB, or larger. This embodiment is described by taking the size of each data block as 16 KB as an example, but does not impose any limitation on the size of the data block. Each data block can be sequentially numbered starting from 0. For example, the logical address of the data block of number 0 is 0KB-15KB; the logical address of the data block of number 1 is 16KB-31KB; the logical address of the data block of number 2 is 32KB. -47KB, and so on. The correspondence between the number of each data block and the logical address can be stored in the memory 213 (as shown in Table 1). It should be noted that the sequential numbering of each data block is only an example of the embodiment. In some cases, only the range of the logical address of each data block needs to be recorded, and it is not required for each data block. Perform sequential numbering.

Numbering	0	1	2	3	4	......
Logical address	0KB-15KB	16KB-31KB	32KB-47KB	48KB-63KB	64KB-79KB	......

Table 1

The bitmap generated by this embodiment will be described below. The bitmap may be stored in the memory 213. In order to prevent data loss when the memory 213 is powered off, a copy may be saved in the disk 22 as a backup.

4A is a schematic diagram of a bitmap of an embodiment of the present invention. As shown in FIG. 4A, the bitmap includes a plurality of bytes. Generally, the controller 21 internally numbers the multiple bytes, for example, byte 0, byte 1, byte 2, ... analogy. Among them, each byte contains 8 bits, such as 0, 1, 2, 3, 4, 5, 6, 7. Among them, the 0th bit is the lowest bit and the 7th bit is the highest bit. In addition, each bit in the bitmap corresponds to one data block. As shown in FIG. 4A, the 0th bit of byte 0 corresponds to the first data block (logical address is 0KB-15KB); the first bit of byte 0 corresponds to the second data block (logical address is 16KB-31KB); byte 0 The second bit corresponds to the third data block (logical address is 32KB-47KB)... The 0th bit of byte1 corresponds to the ninth data block (logical address is 128KB-143KB)... In addition, it can be understood that byte0 corresponds to The logical address of multiple data blocks is 0KB-127KB; the logical address of multiple data blocks corresponding to byte1 is 128KB-255KB... and so on.

In this embodiment, each bit in the bitmap may have two types of marks, one is a mark "1", which means that the data block corresponding to the bit is modified in a certain period of time; the other is the mark "0". Represents that the data block corresponding to the bit has not been modified during this period of time. The bitmap, and the correspondence between each bit in the bitmap and the logical address of the data block, the correspondence between each byte in the bitmap and the logical address of the plurality of data blocks may be stored in the memory 213 in.

Since the bitmap is for data backup, the bitmap reflects the data block that changes during a backup cycle. For example, in the application scenario shown in FIG. 1 or FIG. 2, the production volume periodically backs up the changed data block to the target volume. At the initial moment (for example, time T0), the production volume backs up the data it stores to the target volume and creates a bitmap. When the bitmap is just created, all the bits it contains are set to the flag "0". Suppose T1 is the moment when the next backup task is triggered. The bitmap reflects which data blocks have been modified between T0 and T1 on the production volume. For example, at the time T1, the first bit of byte0 and the 0th bit of byte1 in the bitmap are set to the flag "1", then the data block corresponding to the first bit of byte0 (the logical address is 16 KB) A data block of -31 KB, and a data block corresponding to the 0th bit of byte1 (a data block having a logical address of 128 KB - 143 KB) is modified between time T0 and time T1. That is to say, a data block with a logical address of 16 KB - 31 KB and a data block with a logical address of 128 KB - 143 KB are the difference data to be backed up to the target volume this time. After the data block with the logical address of 16KB-31KB and the data block with the logical address of 128KB-143KB are sent to the target volume, the backup period corresponding to the time T0-T1 is completed, and all the bits of the bitmap are reset. Mark "0". At the time of T2, another backup task is triggered, then the bitmap at this time reflects which data blocks of the production volume are modified between T1 and T2. This again acquires the differential data backup to the target volume and loops accordingly.

In this embodiment, the update of the bitmap for a backup period is done by the information in the log record. The following describes how to modify the bitmap according to the information in the log record in conjunction with FIG. 5.

5 is a flowchart of the method of the present embodiment, which can be applied to the storage device 20 shown in FIG. 1 or applied to the storage device 20 and the storage device 30 shown in FIG. 2, and the execution body thereof is the processing in FIG. 212. Includes the following steps:

Step 601: Obtain a log record in a backup period. The log record includes a starting address of a data block to be written to the production volume and a length of the data block.

The production volume refers to the LU located in the storage device 20, as shown in FIG. 1 or 2.

Taking FIG. 4A as an example, at time T0, when the bitmap is just created, all its bits are set to the flag “0”. Before the time T1, each log record from time T0 to time T1 is read, and the bitmap is modified according to each log record.

For example, the first log record information is: a data block of length 30 KB is written to the start address of 17 KB (where the start address refers to the start address in the production volume) In the storage space. In this embodiment, it is required to determine which bits in the bitmap need to be set to 1 according to the information recorded by the log.

Optionally, the log record may be generated by combining at least two write data requests, and the at least two write data requests include data blocks consecutively. For example, the two write data requests are: writing a data block having a length of 15 KB into a storage space having a starting address of 17 KB; and writing a data block having a length of 15 KB into a storage space having a starting address of 32 KB. . It can be known from the start address and length of the two write requests that their logical addresses are contiguous and thus can be merged into the first log record.

Alternatively, the log record may be generated by a combination of at least two write data requests, the at least two write data requests comprising data blocks that are repeated or partially repeated. For example, two write data requests write a data block of length 30 KB into the storage space with a starting address of 17 KB, except that the contents of the data block are different. Then, the second write data request can be used to overwrite the first write data request, that is, the content recorded by the merged log record is consistent with the content of the second write data request.

In addition, the log record can also be generated by combining at least one write data request and at least one delete data request. For example, the write data request is to write a data block having a length of 15 KB into a storage space having a starting address of 17 KB. The delete data request is to delete a data block whose start address is 17 KB and whose length is 15 KB. Then, the log record generated after the merge is that the data block whose starting address is 17 KB and whose length is 15 KB is not modified. Accordingly, the bitmap does not need to be modified. In addition, in some cases, the logical address of the data block contained in the write data request is repeated with the logical address portion of the data block contained in the delete data request. For example, the write data request is to write a data block having a length of 15 KB into a storage space having a starting address of 17 KB. The delete data request is to delete a data block whose start address is 19 KB and whose length is 13 KB. Then, the log record generated after the merge is to write a data block of length 2 KB into the storage space with a starting address of 17 KB.

Step 602: According to the starting address and the length, and logically corresponding to each byte The address determines the corresponding target byte of the data block in the bitmap.

Specifically, from the start address of 17 KB and the length of 30 KB, it can be seen that the data block to be modified this time corresponds to byte0 of the bitmap shown in FIG. 4A. Therefore, some locations in byte0 need to be marked "1".

Step 603: Determine the number n of bits in the bitmap to be modified according to the start address and the length, and the size of the data block.

Specifically, from the start address of 17 KB and the size of each data block of 16 KB, the number of the first data block to be modified this time is 17/16=1 (the integer part of the quotient). It can be seen from the start address of 17 KB and the length of 30 KB that the end address is 17 KB+30 KB=47 KB, and the last address and the size of each of the data blocks are 16 KB. The number of the last data block to be modified this time is 47/16=2 (the integer part of the quotient). From the data block numbered 1 to the data block numbered 2, there is a total of (2-1+1) = 2 data blocks that need to be modified. Since each bit in the bitmap corresponds to one data block, two bits in byte0 need to be set to the flag "1". In the present embodiment, the number of bits to be set to the mark "1" is indicated by the letter n, where 0 < n <= 8.

Step 604: Determine, according to the starting address, the size of the data block and the number 8 of bits included in each byte to determine a starting bit p in the bit to be modified.

Specifically, the starting address is 17 KB, the size of the data block corresponding to each bit is 16 KB, and the number of bits included in each byte is 8. The starting bit of the byte 0 that needs to be set to the flag "1" is 1 bit. The specific calculation formula is: (17/16) mod8=1. In the present embodiment, the number of the start bit to be set to the mark "1" is indicated by the letter p, where 0 = <p < 8.

Step 605: by the n, the p, and the formula

Calculate the target value. Where n denotes the number of bits that need to be set to the flag "1"; p denotes the number of the start bit that needs to be set to the flag "1". In this embodiment, "n" obtained in step 2 and "p" obtained in step 3 can be used as input values of the following calculation formula to obtain an output value. According to the above example, n=2, P=1, you can get value=6.

Alternatively, a two-dimensional mapping table is set in the memory 213 in advance, as shown in Table 2. The letter n is the abscissa, which represents the number of bits that need to be set to the mark "1"; the letter p is the ordinate, which represents the number of the start bit that needs to be set to the mark "1". The value of each item in the table is determined by the above formula

Calculated. It should be noted that after the value of each item is obtained by the above formula, it is converted into a hexadecimal value and written in Table 2.

Table 2

According to the above example, n=2, p=1, so the value=0x06 can be known by looking up the table.

Step 606: Read the source value saved in the target byte.

The source value refers to the value originally saved in the target byte before the target byte is modified. As can be seen from FIG. 4A, the source value in byte0 is 00000000B.

Step 607: Perform a bit or operation on the target value and the source value, and write the value obtained after performing the bit or operation to the target byte.

The bit or operation refers to performing an OR operation on each bit in the byte. Specifically, after the binary data (00000110B) corresponding to the value (6 or 0x06) obtained in the above step is bit-operated with the source value 00000000B, 00000110B is obtained. Write it to the corresponding byte (ie byte0). In this embodiment, the 0th bit is a low bit, and the following is a high bit. So after writing 00000110B to byte0, the effect is shown in Figure 4B.

Through the above steps, the modification of the bitmap according to the first log record is completed. If there is only the first log record between T0 and T1, then when the backup period arrives at time T1, step 608 may be directly performed: obtaining difference data according to the modified bitmap.

Specifically, when the backup period arrives, it can be seen from the difference bitmap that the first bit and the second bit of the byte 0 change. The logical address of the data block corresponding to the second bit of Byte0 is 16 KB - 31 KB, and the logical address of the data block corresponding to the second bit of byte 0 is 32 KB - 47 KB. Therefore, data (also called difference data) can be obtained from the disk based on the logical addresses of the two data blocks.

Step 609: Back up the difference data to the target volume.

The target volume refers to an LU located at the storage device 20 or the storage device 30, as shown in FIG. 1 or 2.

According to the method described in this embodiment, the difference data is obtained by recording the difference bitmap. When the backup period arrives, only the changed data block needs to be obtained according to the difference bitmap, which reduces the calculation burden and improves the backup efficiency.

In the above embodiment, if there are other log records between the times T0 and T1, after performing step 607, the second log record is read before step 608, for example, the information of the second log record is: the length Write a 60 KB data block with a starting address of 20 KB. According to the above five steps, it can be known that some positions in byte0 need to be marked "1", and the value = 62 is calculated by calculation. The binary data corresponding to 62 is 00111110B. The binary data 00111110B and the original binary data 00000110B in byte0 are bit ORed to obtain 00111110B, and byte0 is written. The effect after writing is as shown in Fig. 4C.

According to the above example, the modification of the bitmap may be completed according to each log record from time T0 to time T1. At time T1, when the backup task is triggered, a data block (ie, difference data) that changes between T0 and T1 is obtained according to the bitmap, and is backed up to the target volume.

In addition, after the backup is completed in this embodiment, all the bits of the bitmap are cleared to mark the data block that has changed in the next backup period.

The embodiment of the invention further provides a difference data backup device 700, where the device 700 is located In a storage system, the storage system includes a memory, a production volume, and a target volume; wherein the production volume includes a plurality of data blocks having the same size, each data block is allocated a continuous logical address; the memory is saved There is a bitmap; the bitmap includes a plurality of bytes, each byte includes 8 bits, and each bit in the bitmap corresponds to one of the production volumes; the apparatus 700 includes:

The log processing module 701 is configured to obtain a log record in a backup period, where the log record includes a start address of a data block to be written into the production volume and a length of the data block.

a bitmap generation module 702, configured to determine, according to the start address and the length, and a logical address corresponding to each byte, a target byte corresponding to the data block in the bitmap; The address and the length, and the size of the data block determine the number of bits to be modified in the bitmap n, 0 < n <= 8; according to the start address, the size of the data block and each word The number 8 of bits included in the section determines the start bit p of the bit to be modified, 0=<p<8; by the n, the p, and the formula

Calculating a target value; reading a source value stored in the target byte; performing a bit or operation on the target value and the source value, and writing a value obtained by performing the bit or operation to the target word Section to modify the bitmap.

The backup module 703 is configured to: when the backup period arrives, obtain difference data according to the modified bitmap; and back up the difference data to the target volume.

The log record may be generated by combining at least two write data requests, the logical addresses of the data blocks included in the at least two write data requests being consecutive or repeated.

The log record may also be generated by combining at least one write data request and at least one delete data request, the logical address of the data block included in the write data request being duplicated with the logical address portion of the data block included in the delete data request .

In addition, the bitmap generation module 702 is further configured to clear each bit of the bitmap after the difference data is backed up into the target volume.

According to the apparatus described in this embodiment, the difference data is obtained by recording the difference bitmap. When the backup period arrives, only the changed data block needs to be obtained according to the difference bitmap, which reduces the calculation burden and improves the backup efficiency.

A person skilled in the art can understand that the foregoing storage medium includes: a USB flash drive, a mobile hard disk, a magnetic disk, an optical disk, a random access memory (RAM), a solid state disk (SSD), or a nonvolatile. A non-transitory machine readable medium that can store program code, such as a non-volatile memory.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not limited thereto.

Claims (12)

1. A differential data backup method, characterized in that the method is applied to a storage system, the storage system comprising a processor, a memory, a production volume and a target volume; wherein the production volume comprises a plurality of data having the same size a block, each data block is allocated a contiguous logical address; the memory holds a bitmap; the bitmap includes a plurality of bytes, each byte includes 8 bits, and each of the bitmaps One bit corresponds to one of the production volumes; the method is performed by the processor, including:

   Obtaining a log record in a backup period, where the log record includes a start address of a data block to be written into the production volume and a length of the data block;

   Determining, according to the start address and the length, and a logical address corresponding to each byte, a corresponding target byte of the data block in the bitmap;

   Determining, according to the starting address and the length, and the size of the data block, the number of bits to be modified in the bitmap n, 0 < n <= 8;

   Determining, according to the starting address, the size of the data block and the number of bits included in each byte, a starting bit p in the bit to be modified, 0=<p<8;

   By the n, the p, and the formula

   

   Calculate the target value;

   Reading the source value saved in the target byte;

   Performing a bit or operation on the target value and the source value, and writing a value obtained after performing the bit or operation to the target byte to modify the bitmap;

   Determining that the backup period arrives, obtaining difference data according to the modified bitmap;

   The difference data is backed up to the target volume.
2. The method of claim 1, wherein the log record is generated by combining at least two write data requests, the logical addresses of the data blocks included in the at least two write data requests being consecutive or repeated.
3. The method according to claim 1, wherein said log record is generated by combining at least one write data request and at least one delete data request, said write data requesting a logical address of said included data block, and said deleting data The logical address portion of the data block contained in the request is repeated.
4. The method of any of claims 1-3, wherein after backing up the difference data into the target volume, the method further comprises clearing each bit of the bitmap.
5. A storage system including a processor, a memory, a production volume, and a target volume, wherein

   The production volume includes a plurality of data blocks having the same size, each data block being allocated a continuous logical address;

   a bitmap is stored in the memory; the bitmap includes a plurality of bytes, each byte includes 8 bits, and each bit in the bitmap corresponds to one data block in the production volume;

   The processor is configured to acquire a log record in a backup period, where the log record includes a start address of a data block to be written into the production volume and a length of the data block;

   Determining, according to the start address and the length, and a logical address corresponding to each byte, a corresponding target byte of the data block in the bitmap;

   Determining, according to the starting address and the length, and the size of the data block, the number of bits to be modified in the bitmap n, 0 < n <= 8;

   Determining, according to the starting address, the size of the data block and the number of bits included in each byte, a starting bit p in the bit to be modified, 0=<p<8;

   By the n, the p, and the formula

   

   Calculate the target value;

   Reading the source value saved in the target byte;

   Performing a bit or operation on the target value and the source value, and writing a value obtained after performing the bit or operation to the target byte to modify the bitmap;

   Determining that the backup period arrives, obtaining difference data according to the modified bitmap;

   The difference data is backed up to the target volume.
6. The storage system according to claim 5, wherein the log record is generated by combining at least two write data requests, and the logical addresses of the data blocks included in the at least two write data requests are consecutive or repeated.
7. The storage system according to claim 5, wherein said log record is generated by combining at least one write data request and at least one delete data request, said write data request includes a logical address of said data block, and said deleting The logical address portion of the data block contained in the data request is partially duplicated.
8. The storage system according to any one of claims 5-7, wherein the processor is further configured to clear each bit of the bitmap after backing up the difference data into the target volume zero.
9. A differential data backup device, wherein the device is located in a storage system, the storage system comprising a memory, a production volume, and a target volume; wherein the production volume includes a plurality of data blocks having the same size, each The data block is allocated a contiguous logical address; the memory holds a bitmap; the bitmap includes a plurality of bytes, each byte includes 8 bits, and each bit in the bitmap corresponds to Describe a data block in a production volume; the device includes:

   a log processing module, configured to acquire a log record in a backup period, where the log record includes a start address of a data block to be written into the production volume and a length of the data block;

   a bitmap generating module, configured to determine, according to the starting address and the length, and a logical address corresponding to each byte, a corresponding target byte of the data block in the bitmap; according to the starting address And the length, and the size of the data block, determining the number of bits to be modified in the bitmap n, 0 < n <= 8; according to the starting address, the size of the data block and each byte The number 8 of bits included determines the start bit p of the bit to be modified, 0=<p<8; by the n, the p, and the formula

   

   Calculating a target value; reading a source value stored in the target byte; performing a bit or operation on the target value and the source value, and writing a value obtained by performing the bit or operation to the target word Section to modify the bitmap;

   And a backup module, configured to: when the backup period arrives, obtain difference data according to the modified bitmap; and back up the difference data to the target volume.
10. The apparatus of claim 9, wherein the log record is generated by combining at least two write data requests, the logical addresses of the data blocks included in the at least two write data requests being consecutive or repeated.
11. The apparatus according to claim 9, wherein said log record is generated by combining at least one write data request and at least one delete data request, said write data requesting a logical address of said included data block, and said deleting data The logical address portion of the data block contained in the request is repeated.
12. The apparatus according to any one of claims 9-11, wherein the bitmap generating module is further configured to: after backing the difference data into the target volume, each of the bitmaps The bit is cleared.

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