WO2016127658A1

WO2016127658A1 - Snapshot processing method and apparatus

Info

Publication number: WO2016127658A1
Application number: PCT/CN2015/092327
Authority: WO
Inventors: 牛克强
Original assignee: 中兴通讯股份有限公司
Priority date: 2015-02-12
Filing date: 2015-10-20
Publication date: 2016-08-18
Also published as: CN105988723A

Abstract

The present invention relates to the technical field of disk arrays. Disclosed are a snapshot processing method and apparatus. The method comprises the following steps: creating snapshot volumes comprising a resource volume, a modification record bitmap, a modification address mapping table and a snapshot mapping table; and during a process of writing a source volume, writing corresponding data in the source volume into the resource volume by using the modification record bitmap, the modification address mapping table and the snapshot mapping table in the snapshot volumes, wherein the modification record bitmap is used for recording modification condition of data blocks in the source volume after the snapshot volumes are established, the modification address mapping table is used for recording an address of a modified region in the source volume and an address in which old data in the region is stored in the resource volume, and the snapshot mapping table is used for recording an address of the source volume and an address in which each data block of the snapshot is stored at the time point, and is used for recording data generated when the snapshot volumes are written. The present invention reduces the influence of a snapshot flow on write IO of a host machine, and improves the efficiency of system and resource volume recovery in snapshot processing.

Description

Snapshot processing method and device

Technical field

The present invention relates to a disk array technology, and in particular, to a snapshot processing method and apparatus.

Background technique

In the snapshot system, the logical volume to be read and written is called the source volume. The auxiliary logical volume that is added to the snapshot is called the resource volume. Differential replication is a convenient and quick way to create snapshots. Differential replication includes two methods. (Copy-on-Write) and Redirect-on-Write. The pre-write copy method is to copy the overwritten data in the source volume to the resource volume and then write the data to the source volume each time a write operation is received; the redirect write method is to directly input the data each time a write operation is received. Write to the resource volume. In the snapshot system, the unit of processing data is stripe-sized data, called a chunk of data chunk.

When reading snapshot data in a snapshot created using the pre-write copy method, if the data block is not modified, it is read directly from the source volume, otherwise it is read from the snapshot volume; in a snapshot created using redirected writes When the source data is read, it is read directly from the source volume if the data has not been modified, otherwise it is read from the snapshot volume. Each time a block of data is read, it is necessary to judge whether the block is modified once, which affects the performance of reading the snapshot volume data. When using these two methods to create a snapshot, the write data operation is similar to the method of reading the data in the snapshot volume. The following describes the pre-write copy method as an example.

Create a snapshot and generate a snapshot. As shown in Figure 1, the process of creating a snapshot and generating a snapshot is as follows:

At time T0, the active volume V1, the resource volume R1, creates a snapshot S0, and generates an address mapping table F0 of S0, which is empty at time T0.

At time T1, the write IO updates A0 on the LBA (Logical Block Address) address corresponding to the source volume chunk 0 to A1. The system first checks that all existing address mapping tables do not have the LBA address for the source volume. Map entry, find that F0 does not, so copy A0 to resource volume R1 before writing, and then update the mapping item (0,0) in F0, meaning that the data of chunk 0 at the time of source volume T0 is currently saved in the chunk 0 position of the resource volume. . Finally, A1 is normally written to the source volume chunk 0.

At time T2, snapshot S2 is created, and an empty address mapping table F2 is created.

At time T3, there is a write IO to update A1 on the source volume chunk 0 address to A3. The system first checks all existing ones. There is no mapping entry for the source volume chunk 0 address in the address mapping table. It is found that F2 is not, so copy A1 to resource volume R1 before writing and a new entry (0, 1) in F2, meaning chunk at source T2 time. The data of 0 is currently stored in the chunk 1 location of the resource volume. Finally, write A3 to the source volume.

At time T4, there is a write IO to update D0 on the source volume chunk 3 address to D4. The system first checks that there are no mapping entries for the source volume chunk 3 address in all existing address mapping tables, and finds that neither F0 nor F2 is written, so write The D0 is copied to the resource volume R1 before, and then the mapping entries (3, 2) are simultaneously updated in F0 and F2, and D4 is written to the source volume.

At time T5, there is a write IO to update D4 on the source volume chunk 3 address to D5. The system first checks that there are no mapping entries for the source volume chunk 3 address in all existing address mapping tables, and finds that both F0 and F2 have, so no Make a pre-write copy and write D5 directly to the source volume.

In summary, the traditional practice when the host writes IO, to determine whether a pre-write copy is required, you need to first check all existing address mapping tables. This requires reading the metadata of all snapshots, which is equivalent to adding IO to the host. Read delay. When the newly written IO is not mapped in all the snapshots, all the snapshot mapping tables need to be modified. First, all the snapshot mapping tables are read and then all the mapping tables are written, and an additional delay is added to the host IO.

The action flow for deleting a snapshot.

Delete the snapshot S0. After receiving the request, the system first scans the F0 address mapping table corresponding to the S0 snapshot, and scans the mapping table of all other snapshots to find out that only the F0 exists and the other snapshot mapping table does not exist in the resource volume. The bitmap is marked as free, and after all entries of F0 are scanned and processed, the entire F0 is deleted.

In the existing method, when you delete a snapshot, you need to scan the deleted snapshot and all other snapshot mapping tables to find out the block of the deleted snapshot exclusive resource volume. That is, only the deleted snapshot maps the resource volume, and all other snapshots do not occupy the snapshot. Block, the block that meets this condition can be recycled. This process needs to read the mapping table of all snapshots, which increases the delay of the deletion process and resource volume recovery.

The existing method deletes a snapshot and traverses the snapshot bitmap. For a bit of 1, the resource volume bitmap of the block is set to 0 (indicating that the block resource is recycled). All existing snapshot bitmaps must be traversed. If other snapshot bitmaps are valid, they cannot be reclaimed. All read bitmap mapping read requests will be generated, which will affect system performance and occupy cache space.

There are several methods in the above method that seriously affect the snapshot efficiency and system performance. First, when the host writes IO, it determines whether a pre-write copy is needed. It is necessary to first check all existing address mapping tables. This requires reading the metadata of all snapshots, which is equivalent to Writing a IO to the host adds a read latency. The second is to delete the mapping table of the deleted snapshot and all other snapshots when deleting the snapshot, which increases the delay of the deletion process and resource volume recovery. The third is when the host is newly written. When there is no entry in the mapping table in all snapshots, the IO needs to modify the mapping table of all snapshots. First, read all the snapshot mapping tables and update them before writing them, adding additional delay to the host IO.

Summary of the invention

The embodiment of the invention provides a snapshot processing method and device to solve at least the problems in the related art that seriously affect the snapshot efficiency and system performance.

According to an aspect of an embodiment of the present invention, a snapshot processing method is provided, including the following steps:

Create a snapshot volume that contains a resource volume, a modified record bitmap, a modified address map, and a snapshot map;

During the writing of the source volume, the corresponding data in the source volume is written into the resource volume by using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume;

The modified record bitmap is used to record the modification of each data block in the source volume after the snapshot volume is established; the modified address mapping table is used to record the address of the modified area in the source volume and the old data of the area is The address stored in the resource volume; the snapshot mapping table is used to record the source volume address and the address of each data block of the point-in-time snapshot, and record the data generated when the snapshot volume is written.

Preferably, the method further comprises:

During the read snapshot, the corresponding data is read from the resource volume and the source volume using the snapshot mapping table and the modified record bitmap in the snapshot volume.

Preferably, the method further comprises:

During the deletion of the snapshot, the modified address mapping table is deleted by using the snapshot mapping table in the snapshot volume.

Preferably, the step of writing the corresponding data in the source volume to the resource volume by using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume includes:

And according to the record of the modified record bitmap, the data to be overwritten in the source volume has been modified, the new data is written into the area corresponding to the data volume to be overwritten by the source volume, and the area address and the area address are recorded in the modified address mapping table. The old data of the area is saved in a mapping relationship of addresses in the resource volume, and the mapping relationship between the area address and the old data of the area is stored in the resource volume and the global index of the resource volume data modification is recorded in the snapshot mapping table. ;

When there is a mapping entry of the data block address to be overwritten in the source volume in the modified address mapping table, according to the modified recording bitmap, the record in the data volume to be overwritten in the source volume is not modified, and the data in the to-be-covered data block is The old data is copied to the corresponding location of the resource volume, and the to-be-covered data block is recorded as having been modified in the modified record bitmap.

Preferably, the step of using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume to write corresponding data in the source volume to the resource volume further includes:

When there is no mapping entry of the data block address to be overwritten in the source volume in the modified address mapping table, according to the modified recording bitmap, the record of the to-be-covered data block in the source volume is not modified, and the data block to be overwritten is The old data is copied to the corresponding location of the resource volume, and the record of the data block to be overwritten in the modified record bitmap is replaced with the record of the old data copied to the corresponding position of the resource volume.

Preferably, the step of reading the corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified recording bitmap in the snapshot volume comprises:

Determining, according to the snapshot mapping table, that the address of the read data in the source volume and the old data of the source volume are saved in an address in the resource volume;

The corresponding data is read from the resource volume and the source volume according to the determined address in the source volume and the source volume old data is saved in the resource volume address.

Preferably, the step of reading the corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified recording bitmap in the snapshot volume further includes:

Determining whether the read data has been pre-write copy according to the mark of the modified record bitmap;

When it is determined that the read data has been pre-write copy, the corresponding data is read from the resource volume;

When it is determined that the read data has not been subjected to a pre-write copy, the corresponding data is read from the source volume.

Preferably, the step of deleting the modified address mapping table by using the snapshot mapping table in the snapshot volume includes:

Deleting the mapping relationship between the source volume and the resource volume by using the mapping relationship between the source volume address and the source volume old data recorded in the snapshot mapping table in the resource volume;

The snapshot volume is deleted according to the mapping relationship between the deleted source volume and the resource volume, and the resource space of the deleted snapshot volume is reclaimed.

Preferably, the step of using the source volume address and the source volume old data recorded in the snapshot mapping table to be saved in an address in the resource volume, and deleting the mapping relationship between the source volume and the resource volume includes:

Determining whether it is necessary to traverse the other modified address mapping table by using the global index modified by the resource volume data recorded in the snapshot mapping table;

When it is determined that the other modified address mapping table needs to be traversed, by scanning an entry existing in the other modified address mapping table, an entry different from the entry in the snapshot mapping table is marked in the resource volume, and the The source volume address and the source volume old data recorded in the snapshot mapping table are saved in the mapping relationship of the addresses in the resource volume, and the mapping relationship between the source volume and the resource volume is deleted;

When it is determined that it is not necessary to traverse the other modified address mapping table, the source volume address and the source volume old data recorded in the snapshot mapping table are saved in a mapping relationship of addresses in the resource volume, and the source volume and the resource volume are deleted. Mapping relationship.

According to another aspect of the embodiments of the present invention, a snapshot processing apparatus is provided, including:

Create a snapshot volume module, set to create a snapshot volume that contains the resource volume, modify the record bitmap, modify the address mapping table, and the snapshot mapping table;

Writing a snapshot module, configured to write a corresponding data in the source volume to the resource volume by using a modified record bitmap, a modified address mapping table, and a snapshot mapping table in the snapshot volume during a write snapshot;

Compared with the prior art, the beneficial effects of the present invention are:

The invention improves the system of snapshot processing, reduces the impact of the snapshot process on the host write IO, and improves the efficiency of resource volume recovery.

DRAWINGS

FIG. 1 is a schematic diagram of creating a snapshot and generating a snapshot provided by the prior art;

2 is a flowchart of a snapshot processing method according to an embodiment of the present invention;

3 is a schematic diagram of a snapshot processing apparatus according to an embodiment of the present invention;

4 is a schematic diagram of a composition of a snapshot time point snapshot data block according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a logical structure of a snapshot volume according to an embodiment of the present invention; FIG.

FIG. 6 is a flowchart of a write snapshot provided by an embodiment of the present invention;

FIG. 7 is a first schematic diagram of a write snapshot provided by an embodiment of the present invention; FIG.

FIG. 8 is a second schematic diagram of a write snapshot provided by an embodiment of the present invention; FIG.

FIG. 9 is a flowchart of a read snapshot provided by an embodiment of the present invention;

FIG. 10 is a flowchart of deleting a snapshot provided by an embodiment of the present invention;

FIG. 11 is a schematic diagram of deleting a snapshot provided by an embodiment of the present invention.

detailed description

The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

FIG. 2 is a flowchart of a snapshot processing method according to an embodiment of the present invention. As shown in FIG. 2, the method includes the following steps:

Step S201: Create a snapshot volume that includes a resource volume, a modified record bitmap, a modified address mapping table, and a snapshot mapping table.

Step S202: During the writing of the source volume, using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume, the corresponding data in the source volume is written into the resource volume;

The present invention also includes reading corresponding data from the resource volume and the source volume by using a snapshot mapping table and a modified recording bitmap in the snapshot volume during a read snapshot.

The present invention also includes deleting the modified address mapping table by using a snapshot mapping table in the snapshot volume during deletion of the snapshot.

Specifically, the step of writing the corresponding data in the source volume to the resource volume by using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume includes: The bitmap is related to the record of the data volume to be overwritten in the source volume, and the new data is written in the area corresponding to the data volume to be overwritten by the source volume, and the area address and the old area are recorded in the modified address mapping table. Data is stored in a mapping relationship of addresses in the resource volume, and the mapping relationship between the area address and the old data of the area in the resource volume and the global index of the resource volume data modification are recorded in the snapshot mapping table; When the mapping entry of the data block address to be overwritten in the source volume exists in the modified address mapping table, according to the modified recording bitmap, the old data in the data block to be overwritten is recorded on the unmodified data block in the source volume. Copying to the corresponding location of the resource volume, and recording the to-be-covered data block as having been modified in the modified record bitmap. When the mapping entry of the data block address to be overwritten in the source volume does not exist in the modified address mapping table, according to the modified record bitmap, the source volume is to be overwritten. Stamping the unmodified record of the data block, copying the old data in the data block to be overwritten into the corresponding position of the resource volume, and replacing the record in the modified record bitmap with the record of the old data copied to the corresponding position of the resource volume The record of the data block to be overwritten.

Specifically, the step of reading corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified recording bitmap in the snapshot volume includes: determining, according to the snapshot mapping table, that the read is performed. The data in the source volume and the source volume old data are saved in the resource volume address; according to the determined address in the source volume and the source volume old data is saved in the resource volume address from the resource volume The corresponding data is read from the source volume. Determining whether the read data has been pre-write copy according to the mark of the modified record bitmap; when determining that the read data has been pre-write copy, reading corresponding data from the resource volume; If the read data has not been pre-write copied, the corresponding data is read from the source volume.

Specifically, the step of deleting the modified address mapping table by using the snapshot mapping table in the snapshot volume includes: using the source volume address and the source volume old data recorded in the snapshot mapping table to be saved The mapping relationship between the source volume and the resource volume is deleted. The snapshot volume is deleted according to the mapping relationship between the deleted source volume and the resource volume, and the resource space of the deleted snapshot volume is reclaimed. The step of deleting the mapping relationship between the source volume and the resource volume by using the source volume address and the source volume old data recorded in the snapshot mapping table is as follows: The global index of the resource volume data modification recorded in the snapshot mapping table is determined whether it is necessary to traverse the other modified address mapping table; when it is determined that the other modified address mapping table needs to be traversed, by scanning other modified address mappings An entry existing in the table, marking an entry in the resource volume different from the entry in the snapshot mapping table, and using the source volume address and the source volume old data recorded in the snapshot mapping table to be saved in the resource volume The mapping relationship between the source volume and the resource volume is deleted; when it is determined that the other modified address mapping table does not need to be traversed, the source volume address and the source volume old data recorded in the snapshot mapping table are used The mapping between addresses in the resource volume is saved, and the mapping relationship between the source volume and the resource volume is deleted.

FIG. 3 is a schematic diagram of a snapshot processing apparatus according to an embodiment of the present invention. As shown in FIG. 3, the method includes: creating a snapshot volume module 301 and a write snapshot module 302. The snapshot volume module 301 is configured to create a snapshot volume that includes a resource volume, a modified record bitmap, a modified address mapping table, and a snapshot mapping table. The write snapshot module 302 is configured to use the snapshot during the write snapshot. The modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume, and the corresponding data in the source volume is written into the resource volume; wherein the modified record bitmap is used to record the snapshot volume Modifying the modification of each data block in the source volume; the modified address mapping table is used Recording the address of the modified area in the source volume and the address in the resource volume where the old data of the area is saved; the snapshot mapping table is used to record the source volume address and the address of each data block of the time point snapshot, and the record write The data that is produced when the snapshot is taken.

The present invention also includes a read snapshot module configured to read the corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified record bitmap in the snapshot volume during the read snapshot; deleting the snapshot module, setting the During the deletion of the snapshot, the modified address mapping table is deleted by using the snapshot mapping table in the snapshot volume.

Further, the write snapshot module 302 includes: a first write snapshot unit, configured to write new data to the source volume to be overwritten according to the modified record bitmap with respect to the record that the data block to be overwritten in the source volume has been modified. Recording, in the corresponding area, the mapping relationship between the area address and the old data of the area in the resource volume in the modified address mapping table, and recording the area address and the area in the snapshot mapping table The old data is saved in the mapping relationship of the addresses in the resource volume and the global index of the resource volume data modification; the second write snapshot unit is set to be when there is a mapping entry of the data block address to be overwritten in the source volume in the modified address mapping table. And copying, according to the modified record bitmap, the old data in the data block to be overwritten into the corresponding position of the resource volume, and in the modified record bitmap, The coverage data block record is reported as having been modified. a third write snapshot unit, configured to: when the map entry of the data block address to be overwritten in the source volume does not exist in the modified address mapping table, according to the modified record bitmap, the record of the data block to be overwritten in the source volume is not modified, Copying the old data in the data block to be overwritten into a corresponding position of the resource volume, and replacing the record of the data block to be covered in the modified record bitmap with the record in which the old data is copied to the corresponding position of the resource volume.

FIG. 4 is a schematic diagram showing the composition of a snapshot time point snapshot data block according to an embodiment of the present invention. As shown in FIG. 4, each data block content in the snapshot is the first modified data or metadata after the snapshot creation time point. When the host reads the data (S, 1), (S, 2), (S, 3), (S, 4) of the snapshot volume, it will query the snapshot mapping table and find that the data block (S, 2) has been written. Pre-copy, the data is saved in the location of the resource volume (R, 1), other data blocks are not pre-write, and the data is saved in the source volume. Therefore, it becomes a read request for the data blocks (B, 1), (R, 1), (B, 3), (B, 4).

FIG. 5 is a schematic diagram showing the logical structure of a snapshot volume according to an embodiment of the present invention. As shown in FIG. 5, the snapshot volume logical structure includes a data area 51, a modified record bitmap 52, a modified address mapping table 53, and a snapshot mapping table 54. Specifically, the data area 51 is used to store old data of the modified area in the snapshot. The modified record bitmap 52 is used to record whether each data block in the source volume is modified after the snapshot is started at the moment. Initialize to 0, if the data is modified, the new data can be written directly to the source volume; if the data has not been modified, the old data needs to be copied to The resource volume is written to the source volume and the bitmap corresponding to the data block is modified. The modified address mapping table 53 is configured to save an address of the modified area in the source volume and an address in which the old data of the area is saved in the resource volume. The snapshot mapping table 54 is configured to save the source volume address and the address where each data block of the time point snapshot is stored. When the snapshot is read, the snapshot content can be directly obtained by reading the data block according to the snapshot data block storage address.

After the snapshot is created, the user reads and writes data, which is affected by the snapshot. The user reads and writes data, including writing data to the source volume, reading the old data of the source volume, and reading the snapshot data. When reading the source volume, it can be directly and not affected by the snapshot. Writing data to the source volume and reading the snapshot are affected by the snapshot.

The present invention provides a snapshot processing method and apparatus, including a source volume and a snapshot volume, specifically, the following steps performed by a source volume and a snapshot volume:

Step 1: Create a snapshot and create a snapshot for a source volume.

Step 2: Write a snapshot and write data to the source volume during the snapshot process.

Step 3: Read the snapshot and read the snapshot data from the snapshot volume after the snapshot is established.

Step 4: Delete the snapshot, reclaim the storage resources occupied by the snapshot, and maintain the source volume as the normal data state.

The snapshot volume includes a data area, a modified record bitmap, and an address mapping table and a snapshot mapping table. The data area is used to store the old data of the modified area in the snapshot; the modified record bitmap is used to record whether each data block in the source volume is modified after the snapshot is started at the moment; and the modified address mapping table is used to save the source volume. The address of the modified area and the old data of the area are saved in the address of the resource volume; the snapshot mapping table is used to save the source volume address and the address of each data block of the time point snapshot. And record the data generated when the snapshot volume is written.

The following describes the process of creating a snapshot, writing a snapshot, reading a snapshot, and deleting a snapshot:

The establishing a snapshot includes the following steps:

Step 1: Assign a new resource volume to the snapshot, allocate the data area, modify the record bitmap, and modify the address mapping table.

Step 2: Initialize the modified record bitmap, and mark all the bits in the bitmap as 0;

Step 3: Initialize the modified address mapping table to create an empty table.

FIG. 6 is a flowchart of a write snapshot provided by an embodiment of the present invention. As shown in FIG. 6, the method includes the following steps:

Step 61: The received IO is divided into data blocks;

The received data of the write IO is divided into manageable blocks, that is, the data is divided according to the smallest unit processed.

Step 62: Determine whether the part of the data is modified;

Take a data block to be processed, check the value of the data block marked in the modified record bitmap, determine whether the source volume data block is to be pre-write, if the source volume data has been modified, proceed to step 66; if the source volume data If it has not been modified, it proceeds to step 63. That is, viewing the data block in the source volume in the modified record bitmap will overwrite the modification flag of the data block, determining whether the source volume data has been modified, and if the data block is modified, proceeding to step 66; if the data block is not If it is modified, the process proceeds to step 63.

Step 63: Copy old data in the source volume to the resource volume.

Copy the old data on the source volume to be overwritten to the resource volume.

Step 64: Modify an address mapping table.

An address mapping table is created for the copied old data, including the address of the old data block in the source volume and the address of the old data block in the resource volume. That is, the relationship between the source volume block address and the resource volume block is established in the modified address mapping table.

Step 65: Update the modified record bitmap;

The source volume data block has been modified in the modified record bitmap. That is, in the modified record bitmap, the modification of the corresponding data block is marked as 1.

Step 66: Write new data to the source volume.

In step 63, when the host writes IO, it is determined whether a pre-write copy is needed. By modifying the record bitmap, the present invention can directly determine whether the source volume has been pre-write copy at various times, as shown in FIG. 7, modifying the record bit. The horizontal view shows the time point of each moment of the source volume, and the vertical direction represents the source volume minimum processing unit.

Specifically, in step 63, when the newly written IO of the host is not mapped in all the snapshots, the present invention solves the problem by modifying the record bitmap and the location of the resource volume. In the following scenario, the host writes C1 at time T4. By modifying the record bitmap, it is found that there is no mapping for C1 for all snapshots, indicating that C1 needs to be pre-write, and all mappings need to be modified for C1 mapping table (modify the mapping table of all times T0, T1, T2, T3, T4) As shown in FIG. 8, the present invention firstly uses the pre-write copy mechanism to copy the source volume data into the resource volume. It is not necessary to modify the mapping entries in all the snapshot mapping tables, and only needs to change the storage location of the source volume data to the resource volume. R0 in the middle, and the record of the data block to be overwritten in the modified record bitmap is replaced with the record in which the old data is copied to the corresponding position of the resource volume.

FIG. 9 is a flowchart of a read snapshot provided by an embodiment of the present invention. As shown in FIG. 9, the method includes the following steps:

Step 91: Receive a read request sent by the host.

Step 92: Read a snapshot mapping table at a time point of the read snapshot;

First, the data in the snapshot mapping table is checked to determine the storage location of the data in the snapshot volume. If there is data in the snapshot volume, the data of the snapshot volume is directly returned to the host; if there is no data in the snapshot volume, step S93 is performed. That is, the storage location of the data in the snapshot volume is determined from the snapshot mapping table. If the data has a storage location in the snapshot volume, the data of the snapshot volume is directly returned to the host. If the data does not have a storage location in the snapshot volume, Then step S93 is performed.

Step 93: Check the modified record bitmap to determine the location of the data in the resource space and the source volume. If the value of the modified record bitmap is 0, it indicates that no pre-write copy has been made, and the corresponding data is read from the source volume; The record bitmap value is 1, and the corresponding data is read from the resource volume. The resource volume block number is modified when the snapshot is written, as described in the previous procedure.

FIG. 10 is a flowchart of deleting a snapshot provided by an embodiment of the present invention. As shown in FIG. 10, when a user does not need a snapshot, the created snapshot may be deleted, and the following steps are included:

Step 101: Delete a logical relationship between the source volume and the resource volume.

Step 102: Delete a snapshot volume.

Step 103: Reclaim resource space.

The invention redesigns the structure of the snapshot mapping table, and increases the global index index of the snapshot creation and resource volume block data modification. For example, when S0 is created, the index is 0, and the index of the chunk 0 modified by S0 is 1. The list is as follows: Table 1: Relationship between snapshot creation and resource volume block data modification and index.

Table 1: Relationship between snapshot creation and resource volume block data modification and index

索引 index		事件event
00	创建快照S0 Create snapshot S0
11	将源卷chunk 0修改为A1Modify the source volume chunk 0 to A1
22	将源卷chunk 7修改为E2Modify the source volume chunk 7 to E2
33	创建快照S1 Create snapshot S1
44	将源卷chunk 2修改为B2Modify source volume chunk 2 to B2
55	创建快照S2 Create snapshot S2
66	将源卷chunk 0修改为A2Modify the source volume chunk 0 to A2

Optimize the mapping table of the snapshot and add the index entries. As shown in Figure 11, according to the original method, when S1 is deleted, when the two mappings of S1 are deleted, it is necessary to scan in S1 but not in all other snapshot mapping tables. Existing entries, for example, look for chunk 0, chunk 2 entries in the S0 and S2 mapping tables. The invention passes Index entries are added to the snapshot mapping table. You can compare the size of the index when deleting. For example, delete S1 and compare the index value. The index value 6 for the entry chunk 0 is greater than the creation index 5 of S2. Therefore, you need to traverse S0 and S2 for chunk 0. However, for the chunk 2 entry, since the index value 4 is larger than the index value 0 of S0 and smaller than the creation index value 5 of S2, it means that S2 does not share the data of the resource volume chunk 1, so the source volume chunk 2 entry only checks S0, does not check. S2, which saves the request to read the S2 mapping entry, and saves system resources, including CPU, cache, and scheduling, when the mapping entry cannot be fully memory.

In summary, the present invention has the following technical effects:

The invention reduces the impact of the snapshot process on the host write IO, and improves the efficiency of the snapshot processing system and the resource volume recovery.

The serial numbers of the embodiments of the present invention are merely for the description, and do not represent the advantages and disadvantages of the embodiments.

In the above-mentioned embodiments of the present invention, the descriptions of the various embodiments are different, and the parts that are not detailed in a certain embodiment can be referred to the related descriptions of other embodiments.

In the several embodiments provided by the present application, it should be understood that the disclosed technical contents may be implemented in other manners. The device embodiments described above are only schematic. For example, the division of the unit may be a logical function division. In actual implementation, there may be another division manner, for example, multiple units or components may be combined or may be Integrate into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, unit or module, and may be electrical or otherwise.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a standalone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, or all or part of the technical solution, may be embodied in the form of a software product stored in a storage medium. Including several instructions to make A computer device (which may be a personal computer, server or network device, etc.) may be used to perform all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: a U disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic disk, or an optical disk, and the like. .

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Industrial applicability

As described above, the snapshot processing method and apparatus provided by the embodiments of the present invention have the following beneficial effects: reducing the impact of the snapshot process on the host write IO, and improving the efficiency of the snapshot processing system and resource volume recovery.

Claims

A snapshot processing method includes the following steps:

Create a snapshot volume that contains a resource volume, a modified record bitmap, a modified address map, and a snapshot map;

During the writing of the source volume, the corresponding data in the source volume is written into the resource volume by using the modified record bitmap, the modified address mapping table, and the snapshot mapping table in the snapshot volume;

The modified record bitmap is used to record the modification of each data block in the source volume after the snapshot volume is established; the modified address mapping table is used to record the address of the modified area in the source volume and the old data of the area is The address stored in the resource volume; the snapshot mapping table is used to record the source volume address and the address of each data block of the point-in-time snapshot, and record the data generated when the snapshot volume is written.
The method of claim 1 further comprising:

During the read snapshot, the corresponding data is read from the resource volume and the source volume using the snapshot mapping table and the modified record bitmap in the snapshot volume.
The method of claim 1 or 2, further comprising:

During the deletion of the snapshot, the modified address mapping table is deleted by using the snapshot mapping table in the snapshot volume.
The method according to claim 1, wherein said utilizing said modified record bitmap, said modified address mapping table and said snapshot mapping table in said snapshot volume, said corresponding data in said source volume is written into said resource volume The steps include:

And according to the record of the modified record bitmap, the data to be overwritten in the source volume has been modified, the new data is written into the area corresponding to the data volume to be overwritten by the source volume, and the area address and the area address are recorded in the modified address mapping table. The old data of the area is saved in a mapping relationship of addresses in the resource volume, and the mapping relationship between the area address and the old data of the area is stored in the resource volume and the global index of the resource volume data modification is recorded in the snapshot mapping table. ;

When there is a mapping entry of the data block address to be overwritten in the source volume in the modified address mapping table, according to the modified recording bitmap, the record in the data volume to be overwritten in the source volume is not modified, and the data in the to-be-covered data block is The old data is copied to the corresponding location of the resource volume, and the to-be-covered data block is recorded as having been modified in the modified record bitmap.
The method according to claim 4, wherein said utilizing said modified record bitmap, said modified address mapping table and said snapshot mapping table in said snapshot volume, said corresponding data in said source volume is written into said resource volume The steps also include:

When the mapping entry of the data block address to be overwritten in the source volume does not exist in the modified address mapping table, according to the repair Changing the record bitmap with respect to the record in the source volume that the data block to be overwritten is not modified, copying the old data in the data block to be overwritten into the corresponding location of the resource volume, and copying the old data to the corresponding position of the resource volume Recording a record replacing the block of data to be covered in the modified record bitmap.
The method of claim 2, wherein the step of reading the corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified recording bitmap in the snapshot volume comprises:

Determining, according to the snapshot mapping table, that the address of the read data in the source volume and the old data of the source volume are saved in an address in the resource volume;

The corresponding data is read from the resource volume and the source volume according to the determined address in the source volume and the source volume old data is saved in the resource volume address.
The method of claim 6, wherein the step of reading the corresponding data from the resource volume and the source volume by using the snapshot mapping table and the modified recording bitmap in the snapshot volume further comprises:

Determining whether the read data has been pre-write copy according to the mark of the modified record bitmap;

When it is determined that the read data has been pre-write copy, the corresponding data is read from the resource volume;

When it is determined that the read data has not been subjected to a pre-write copy, the corresponding data is read from the source volume.
The method of claim 3, wherein the step of deleting the modified address mapping table by using the snapshot mapping table in the snapshot volume comprises:

Deleting the mapping relationship between the source volume and the resource volume by using the mapping relationship between the source volume address and the source volume old data recorded in the snapshot mapping table in the resource volume;

The snapshot volume is deleted according to the mapping relationship between the deleted source volume and the resource volume, and the resource space of the deleted snapshot volume is reclaimed.
The method according to claim 8, wherein said utilizing said source volume address and source volume old data recorded in said snapshot mapping table are stored in a mapping relationship of addresses in a resource volume, and deleting source volume and resource volume The steps of the mapping relationship include:

Determining whether it is necessary to traverse the other modified address mapping table by using the global index modified by the resource volume data recorded in the snapshot mapping table;

When it is determined that the other modified address mapping table needs to be traversed, by scanning an entry existing in the other modified address mapping table, an entry different from the entry in the snapshot mapping table is marked in the resource volume, and the The source volume address and the source volume old data recorded in the snapshot mapping table are saved in the mapping relationship of the addresses in the resource volume, and the mapping relationship between the source volume and the resource volume is deleted;

When it is determined that it is not necessary to traverse the other modified address mapping table, the source volume address and the source volume old data recorded in the snapshot mapping table are saved in a mapping relationship of addresses in the resource volume, and the source volume and the resource volume are deleted. Mapping relationship.
A snapshot processing device includes:

Create a snapshot volume module, set to create a snapshot volume that contains the resource volume, modify the record bitmap, modify the address mapping table, and the snapshot mapping table;

Writing a source volume module, configured to write corresponding data in the source volume to the resource volume by using a modified record bitmap, a modified address mapping table, and a snapshot mapping table in the snapshot volume during writing of the source volume;

The modified record bitmap is used to record the modification of each data block in the source volume after the snapshot volume is established; the modified address mapping table is used to record the address of the modified area in the source volume and the old data of the area is The address stored in the resource volume; the snapshot mapping table is used to record the source volume address and the address of each data block of the point-in-time snapshot, and record the data generated when the snapshot volume is written.