WO2016029744A1

WO2016029744A1 - Metadata recovery method and relevant device

Info

Publication number: WO2016029744A1
Application number: PCT/CN2015/083226
Authority: WO
Inventors: 刘洋; 张克星
Original assignee: 华为技术有限公司
Priority date: 2014-08-27
Filing date: 2015-07-02
Publication date: 2016-03-03
Also published as: CN104202387B; CN104202387A

Abstract

Disclosed are a metadata recovery method and a relevant device. The method can comprise: receiving a write operation request for a target file, wherein the target file is saved in multiple data nodes; acquiring metadata of the target file from a namenode, the metadata of the target file containing information about the multiple data nodes; generating metadata recovery information according to the metadata of the target file; and sending the metadata recovery information to at least one data node of the multiple data nodes, the metadata recovery information being used for being saved by the at least one data node, and being sent to the namenode for recovering the metadata when abnormality occurs to the namenode. The embodiments of the present invention can recover metadata when abnormality occurs to an NN.

Description

Metadata recovery method and related device

Technical field

The present invention relates to the field of communications, and in particular, to a metadata recovery method and related apparatus.

Background technique

Hadoop is a widely distributed distributed system architecture in the communication field. It contains a very important storage component in Hadoop, namely Hadoop Distributed File System (HDFS). The HDFS includes a metadata node (NameNode, NN for short) and a data node (DataNode, DN for short). The NN is mainly used to provide a metadata service for the file. In the service, the NN generates metadata of the file in the memory, and the metadata. Can represent the data structure of the file, and DN is mainly used to store the actual data of the file. In an actual application, when an NN is abnormal, the NN will have a problem of metadata loss, causing the NN to fail.

Among them, the above problems are mainly solved by the following technologies:

A timing thread is opened inside the NN, which periodically writes the metadata in the NN memory to the local disk or the remote storage device to form a specific file. When the NN is abnormal, the NN loads the specific file during the restart process to recover the metadata of the previous period to achieve the memory state of the NN recovery to this period.

However, in the above technical solution, since the metadata in the NN is periodically stored, for example, the metadata is stored every ten minutes, so that when the time when the NN is abnormal has not reached the storage time point of ten minutes, then the NN Metadata in the event of an exception is not stored, so this part of the metadata cannot be recovered. It can be seen that the metadata of the NN anomaly cannot be recovered in the above technical solution.

Summary of the invention

The invention provides a metadata recovery method and related device, which can recover metadata when an NN is abnormal.

In a first aspect, the present invention provides a metadata recovery method, including:

Receiving a write operation request to the target file, wherein the target file is saved on multiple DNs;

Obtaining metadata of the target file from the NN, the metadata of the target file containing information of the plurality of DNs;

Generating metadata recovery information according to metadata of the target file;

Transmitting the metadata recovery information to at least one of the plurality of DNs for saving by the at least one DN and transmitting to the NN after an exception occurs in the NN The recovery of the metadata is performed.

In a first possible implementation manner of the first aspect, the target file is divided into multiple data blocks, where the multiple data blocks are saved on the multiple DNs;

Then, the acquiring the metadata of the target file from the NN, and generating the metadata recovery information according to the metadata of the target file includes:

Obtaining metadata of the plurality of data blocks from the NN, the metadata of each data block includes information of each data block and information of a DN where each of the data blocks is located;

Generating metadata recovery information for each of the data blocks based on the metadata of each of the data blocks.

With reference to the first possible implementation of the first aspect, in a second possible implementation, the acquiring, by the NN, the metadata of the multiple data blocks includes:

Receiving metadata of each of the data blocks sent by the NN in sequence; or receiving metadata of all data blocks that the NN requests to be sent at one time according to a write operation of the target file.

With reference to the first possible implementation manner of the first aspect or the second possible implementation manner, in a third possible implementation manner, the received metadata includes at least metadata of the first data block and the second data block Metadata, where:

The generated metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The generated metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

In a third aspect, the present invention provides a metadata recovery method, including:

Receiving metadata recovery information of the target file sent by the client, and saving the metadata recovery information, wherein the metadata recovery information is obtained by the client from the NN when receiving a write operation request for the target file Metadata of the target file, and metadata recovery information generated according to the metadata.

After the NN has an abnormality, the metadata recovery information is sent to the NN, and the metadata recovery information is used by the NN to perform recovery of the metadata.

In a first possible implementation manner of the second aspect, the target file is divided into multiple data blocks, and the metadata recovery information of the target file sent by the receiving client includes:

And receiving metadata recovery information of the data block of the target file sent by the client, where the metadata recovery information of the data block is metadata recovery information generated by the client according to the metadata of the data block.

With reference to the first possible implementation of the second aspect, in a second possible implementation manner of the second aspect, the receiving the metadata recovery information of the data block of the target file that is sent by the client includes:

Receiving metadata recovery information of the plurality of data blocks of the target file sent by the client endpoint in sequence; or receiving metadata recovery information of the plurality of data blocks of the target file sent by the client at one time.

In conjunction with the first possible implementation of the second aspect or the second possible implementation, in a third possible implementation of the second aspect, the received metadata recovery information is at least The metadata recovery information of the first data block and the metadata recovery information of the second data block, wherein:

The metadata recovery information of the first data block includes:

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

Receiving a write operation request to the target file sent by the client, where the target file is saved on multiple DNs;

Generating metadata of the target file, and transmitting the metadata to the client, wherein the metadata includes information of the plurality of DNs;

Receiving, by the local end, metadata recovery information sent by at least one of the plurality of DNs, and recovering the metadata according to the metadata recovery information, wherein the metadata recovery information is The metadata recovery information generated by the client according to the metadata and sent by the client to the at least one DN for saving.

In a first possible implementation manner of the third aspect, the target file is divided into multiple data blocks, where the multiple data blocks are saved on the multiple DNs;

And generating the metadata of the target file, and sending the metadata to the client includes:

Generating metadata of the plurality of data blocks, and transmitting metadata of the plurality of data blocks to the client, where metadata of each data block includes information of each data block and where each of the data blocks is located Information of the DN;

Receiving the metadata recovery information sent by the at least one of the plurality of DNs, and recovering the metadata according to the metadata recovery information, including:

Receiving metadata recovery information of the plurality of data blocks transmitted by at least one of the plurality of DNs, and recovering metadata of the target file according to metadata recovery information of the plurality of data blocks.

In conjunction with the first possible implementation of the third aspect, in a second possible implementation manner of the third aspect, the sending, by the client, the metadata of the multiple data blocks includes:

Transmitting metadata of the plurality of data blocks to the client in turn; or sending metadata of all data blocks to the client at a time according to a write operation request of the target file.

With reference to the first possible implementation manner of the third aspect, or the second possible implementation manner, in a third possible implementation manner of the third aspect, the multiple data blocks include at least a first data block and a second Data block, where:

The metadata recovery information of the first data block includes:

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

In a fourth aspect, the present invention provides a client, including: a receiving unit, an obtaining unit, a generating unit, and a sending unit, where:

The receiving unit is configured to receive a write operation request for the target file, where the target file is saved on multiple DNs;

The acquiring unit is configured to acquire metadata of the target file from an NN, where metadata of the target file includes information of the multiple DNs;

The generating unit is configured to generate metadata recovery information according to metadata of the target file;

The sending unit is configured to send the metadata recovery information to at least one of the plurality of DNs, where the metadata recovery information is used to be saved by the at least one DN, and The NN is sent to the NN for recovery of the metadata after an abnormality occurs.

In a first possible implementation manner of the fourth aspect, the target file is divided into multiple data blocks, where the multiple data blocks are saved on the multiple DNs;

Then, the obtaining unit is configured to acquire metadata of the plurality of data blocks from the NN, and the metadata of each data block includes information of each data block and information of a DN where each of the data blocks is located;

The generating unit is configured to generate metadata recovery information of each of the data blocks according to the metadata of each of the data blocks.

With reference to the first possible implementation manner of the fourth aspect, in a second possible implementation manner of the fourth aspect, the acquiring unit is configured to sequentially receive metadata of each data block that is sent by the NN; Alternatively, the obtaining unit is configured to receive metadata of all data blocks that are sent by the NN according to a write operation of the target file.

With reference to the first possible implementation manner of the fourth aspect, or the second possible implementation manner, in a third possible implementation manner of the fourth aspect, the received metadata includes at least metadata of the first data block And the metadata of the second data block, where:

The generated metadata recovery information of the first data block includes:

The generated metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

In a fifth aspect, the present invention provides a DN, including: a receiving unit and a sending unit, where:

The receiving unit is configured to receive metadata recovery information of the target file sent by the client, and save the metadata recovery information, where the metadata recovery information is that the client receives a write operation on the target file. When requested, the metadata of the target file obtained from the NN is based on Metadata recovery information generated by the metadata.

The sending unit is configured to send the metadata recovery information to the NN after an abnormality occurs in the NN, where the metadata recovery information is used by the NN to perform recovery of the metadata.

In a first possible implementation manner of the fifth aspect, the target file is divided into multiple data blocks, and the receiving unit is configured to receive metadata recovery of the data block of the target file that is sent by the client Information, the metadata recovery information of the data block is metadata recovery information generated by the client according to metadata of the data block.

With reference to the first possible implementation manner of the fifth aspect, in a second possible implementation manner of the fifth aspect, the receiving unit is configured to receive, in sequence, multiple data blocks of the target file that are sent by the client endpoint The metadata recovery information is used; or the receiving unit is configured to receive metadata recovery information of the plurality of data blocks of the target file that are sent by the client at one time.

With reference to the first possible implementation manner of the fifth aspect, or the second possible implementation manner, in a third possible implementation manner, the received metadata recovery information includes at least metadata recovery information of the first data block. And metadata recovery information for the second data block, wherein:

The metadata recovery information of the first data block includes:

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

In a sixth aspect, the present invention provides an NN, including: a receiving unit, a generating unit, and a restoring unit, where:

The receiving unit is configured to receive a write operation request for the target file sent by the client, where the target file is saved on multiple DNs;

The generating unit is configured to generate metadata of the target file, and send the data to the client The metadata, wherein the metadata includes information of the plurality of DNs;

The recovery unit is configured to receive metadata recovery information sent by at least one of the plurality of DNs when an abnormality occurs on the local end, and recover the metadata according to the metadata recovery information, where The metadata recovery information is metadata recovery information generated by the client according to the metadata, and sent by the client to the at least one DN for saving.

In a first possible implementation manner of the sixth aspect, the target file is divided into multiple data blocks, where the multiple data blocks are saved on the multiple DNs;

The generating unit is configured to generate metadata of the plurality of data blocks, and send metadata of the plurality of data blocks to the client, where metadata of each data block includes information and information of each data block Information about the DN where each data block is located;

The recovery unit is configured to receive metadata recovery information of the plurality of data blocks sent by at least one of the plurality of DNs when an abnormality occurs on the local end, and recover the metadata according to the plurality of data blocks. The information recovers the metadata of the target file.

With reference to the first possible implementation manner of the sixth aspect, in a second possible implementation, the generating unit is configured to generate metadata of the multiple data blocks, and send the Metadata of a plurality of data blocks; or the generating unit is configured to generate metadata of the plurality of data blocks, and send metadata of all data blocks to the client at a time according to a write operation request of the target file .

With reference to the first possible implementation or the second possible implementation of the sixth aspect, in a third possible implementation, the multiple data blocks include at least a first data block and a second data block, where :

The metadata recovery information of the first data block includes:

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.

In the above technical solution, receiving a write operation request for the target file, acquiring metadata of the target file from the NN, generating metadata recovery information according to the metadata of the target file, and then performing at least one of the plurality of DNs A DN sends the metadata recovery information. Thus the metadata recovery information can be used for saving by the at least one DN and sent to the NN for recovery of the metadata after an exception occurs in the NN. Thereby, the metadata when the NN is abnormal can be restored.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

1 is a schematic diagram of an optional metadata provided by an embodiment of the present invention;

2 is a schematic flowchart of a metadata recovery method according to an embodiment of the present invention;

3 is a schematic flowchart of another metadata recovery method according to an embodiment of the present invention;

4 is a schematic diagram of an optional data information provided by an embodiment of the present invention;

FIG. 5 is a schematic flowchart diagram of another metadata recovery method according to an embodiment of the present invention;

FIG. 6 is a schematic flowchart diagram of another metadata recovery method according to an embodiment of the present invention;

FIG. 7 is a schematic flowchart diagram of another metadata recovery method according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a client according to an embodiment of the present disclosure;

9 is a schematic structural diagram of a DN according to an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a NN according to an embodiment of the present disclosure;

FIG. 11 is a schematic structural diagram of another metadata recovery device according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of a DN device according to an embodiment of the present disclosure;

FIG. 13 is a schematic structural diagram of an NN device according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

In the embodiment of the present invention, the metadata may be data for indicating a file data structure, where the metadata of the file may specifically represent version information of the HDFS system where the file is located and attribute information of the file, for example, metadata of the file. The version information of the included HDFS system may include one or more of the following:

The version information of the HDFS system (for example, imgVersion), the namespace identifier (for example, namespaceID), the number of files of the HDFS system (for example, numFiles), and the time stamp of the HDFS system (for example, genStamp);

The attribute information of the file included in the metadata of the file may include one or more of the following:

The path of the file (for example: Path), the number of copies of the file (for example: replicas), the access time of the file (for example: atime), the size of each data block of the file (for example: blockSize), and the number of blocks of the data block of the file ( For example: numBlock), limit information for the space occupied by the file (for example: nsQuota and dsQuota) and user permission information (for example: username, group, and perm).

In addition, when the file includes a plurality of data blocks, the metadata of the file may further include metadata of each data block, where the metadata of the data block includes attribute information of the file to which the data block belongs and attribute information of the data block; The attribute information of the data block may include one or more of the following:

The data block identifier (for example: BlockId), the amount of data stored in the data block (for example: numBytes), and the time stamp of the data block (for example: genStamp). In addition, the attribute information of the file has been described above, and the description is not repeated here.

For example, the metadata of the file can be as shown in FIG. 1, and the metadata of the file can include the one in FIG. Three lines of data, where the first line represents the version information of the HDFS system, the second line represents the attribute information of the file, and the third line represents the metadata of the data block. That is, the metadata of the file may include version information of the HDFS system, attribute information of the file, and metadata of the data block.

In addition, the scenario to which the embodiment of the present invention is applied may be a single device, that is, the client including the HDFS, the at least one NN, and the at least one DN; or the scenario applied by the embodiment of the present invention may be a device cluster, that is, a client of the HDFS. At least one NN and at least one DN are deployed on multiple devices. The device may be a network side device, for example, a base station, a server, a controller, etc., and the device may also be a user side device, such as a computer, a tablet computer, a mobile phone, an e-reader, a remote controller, a notebook computer, and a car. A smart device with network capabilities such as devices, network TVs, and wearable devices.

Referring to FIG. 2, FIG. 2 is a schematic flowchart of a metadata recovery method according to an embodiment of the present invention. As shown in FIG. 2, the method includes the following steps:

201. Receive a write operation request for the target file, where the target file is saved on multiple DNs.

The foregoing target file is saved on multiple DNs, and may be in response to the foregoing write operation request, and the target file is saved on multiple DNs, wherein the time of the save process is not limited, for example, after step 204, or in step Before 204.

202. Obtain metadata of the target file from an NN, where metadata of the target file includes information of the multiple DNs.

Optionally, when receiving the foregoing write operation request, the local end may apply to the NN for multiple DNs for saving the target file, so that the NN may allocate the NN for the target file, and generate metadata of the target file. And return the metadata of the target file to the above end. Further, the information of the plurality of DNs may be path information in which the DN stores the target file, for example, the path of the file in the attribute information of the file introduced above.

203. Generate metadata recovery information according to metadata of the target file.

Optionally, the metadata recovery information may include metadata of the target file, for example, including attribute information of the target file. The attribute information may include one or more of the following:

Version information of the HDFS system, file name, space limit information occupied by the file, user authority information, each data block size of the file, and the number of blocks of the data block of the file.

The file name may also carry path information of the file.

204. Send the metadata recovery information to at least one of the plurality of DNs, where the metadata recovery information is used to be saved by the at least one DN, and is sent to the The NN performs the recovery of the metadata.

Optionally, the foregoing method can be applied to a client of the HDFS, that is, the client can implement the foregoing method.

Referring to FIG. 3, FIG. 3 is a schematic flowchart of another metadata recovery method according to an embodiment of the present invention. As shown in FIG. 3, the method includes the following steps:

301. Receive a write operation request for a target file, where the target file is divided into a plurality of data blocks, and the plurality of data blocks are saved on the plurality of DNs.

Optionally, the data write operation on the target file may be performed in units of data blocks, that is, an object file may be divided into multiple data blocks, wherein the size of each data block is Can be the same. For example: each data block can be 64 megabytes (MB) or 128 MB. In addition, the size of the foregoing data block may be the storage space size of the data block, but in actual applications, the data amount of the file stored in each data block of one file may be different, for example, one file contains 150 MB of data, and each The size of the data block is 64MB, then the first data block of the file can store 64MB of data of the file, and the second data block can store 64MB of data of the file, and the third data block can store the data. 22MB of data for the file.

302. Obtain metadata of the plurality of data blocks from the NN, and metadata of each data block includes information of each data block and information of a DN where each of the data blocks is located.

Optionally, when receiving the foregoing write operation request, the local end may apply to the NN for multiple data blocks for saving the target file, and save multiple DNs of the data block. Thus, the NN can allocate a data block for the object file, and the DN of the data block, and generate metadata for each data block, and return the metadata of each data block to the above end. In addition, the information of the foregoing data block may be attribute information of the data block, for example, a data block identifier and a time stamp of the data block. The information of the plurality of DNs may be path information of each DN save data block, for example, the path of the file in the attribute information of the file described above.

303. Generate metadata recovery information of each data block according to the metadata of each data block.

Optionally, the metadata recovery information of the data block may include metadata of the data block, for example, including attribute information of the target file.

304. Send the metadata recovery information to at least one of the plurality of DNs, where the metadata recovery information is used to be saved by the at least one DN, and is sent to the NN after an abnormality occurs in the NN. The NN performs recovery of the metadata of the target file.

Since the above metadata recovery information is saved by one or more DNs, it is possible to prevent the metadata recovery information from being lost after an abnormality occurs in a single DN.

Optionally, the obtaining the metadata of the multiple data blocks from the NN may include:

The metadata of each of the data blocks sent by the NN is sequentially received.

For example, the local end may apply for a data block to the NN each time, so that the NN allocates a data block to the target file, and generates metadata of the data block, and returns the metadata of the data block to the local end. When the data block is written, and the target file has not been written, the local end requests another data block from the NN, and the NN allocates another data block for the target file, and generates metadata of the data block. And return the metadata of the data block to the above end. When the above data block is written, and the target file has not been written, continue to apply for the data block to the NN until the target file is written. Therefore, step 303 may be that the local end acquires the metadata recovery information of the data block for each time, and then generates the metadata recovery information of the data block to the at least one DN.

Receiving, by the NN, metadata of all data blocks that are sent at one time according to a write operation of the target file.

For example, the local end may apply for multiple data blocks to the NN at one time, so that the NN allocates multiple data blocks for the target file, and generates metadata of the data blocks, and returns the metadata of the data blocks to the local end. . Thus, step 303 may be to generate metadata recovery information of a plurality of data blocks at a time, and step 304 further transmits metadata recovery information of the plurality of data blocks to the at least one DN.

Optionally, the received metadata includes at least metadata of the first data block and metadata of the second data block, that is, the target file is at least divided into the first data block and the second data block.

The metadata recovery information of the generated first data block may include:

Attribute information of the object file and location information of the first data block in the object file.

The attribute information of the target file may include:

The version information of the HDFS system, the file name, the number of copies of the file, the size of each block of the file, the limit information of the space occupied by the file, and the user authority information.

The location information of the first data block in the target file may be a data block number of the target file of the first data block. For example, the first data block may be a data block with a sequence number of 1 of the target file, where The data block with the sequence number 1 may be one of the earliest data blocks in the target file; the location information of the first data block in the target file may include:

Data block number and file end block information.

The metadata recovery information of the generated second data block may include:

Location information of the second data block in the target file.

The location information of the second data block in the target file may include:

Data block number and file end block information.

In addition, the metadata recovery information of the second data block may further include version information and a file name of the HDFS system, so that it can be clearly known that the metadata recovery information of the second data block is a data block for recovering which file, and the The version information of the file's HDFS system.

For example, as shown in FIG. 4a, the metadata recovery information of the first data block may include:

The version information of the HDFS system, the file name, the number of copies of the file, the size of each data block of the file, the restriction information of the space occupied by the file, the user authority information, the data block number, and the file end block information.

As shown in FIG. 4b, the metadata recovery information of the first data block may include:

Version information, file name, data block number, and file end block information of the HDFS system.

The file end data block information may be represented by whether the current data block is an end block. For example, the file end data block information in the metadata recovery information of the first data block may be represented by a false (false); When the target file includes only two data blocks, then the file end data block information in the metadata recovery information of the first data block may be a true (true) table. When the target file includes three or more data blocks, the metadata recovery information of the first data block and the file end data block information in the metadata recovery information of the second data block may be false ( False) indicates that in this embodiment, only the file end block information corresponding to the last data block of the target file is represented by true (true), and the rest are represented by false (false), so that the data block can be ended according to the file. The information can determine the number of data blocks included in the target file.

In addition, since the metadata of each data block in a file may include the attribute information of the file, and the attribute information of the file is the same, for example, the restriction information of the space occupied by the file, the user authority information, the size information and the copy of the data block. The number of information is the same, so that only the information needs to be written in the metadata recovery information of one of the data blocks, thereby saving the storage space of other DNs.

In addition, the foregoing describes only a plurality of optional implementation manners of the metadata recovery information of the first data block and the second data block, which is not limited in this embodiment, for example, metadata recovery of the first data block. Information can also include:

Version information of the HDFS system, file name, number of copies of the file, access time of the file, number of blocks of the data block of the file, limit information of the space occupied by the file, user permission information, data block identifier, size of the data block, and data block Timestamp.

Optionally, before obtaining the metadata of the data block sent by the NN, the method may be an application request for sending a data block to the NN, and after receiving the request, the NN may allocate a data block for the target file, and store the data. The DN of the data block. In addition, before step 301, the method may further include the following steps:

Create a target file and generate summary information about the target file. For example: generate information such as the file name of the file.

In the above technical solution, receiving a write operation request for the target file, acquiring metadata of the plurality of data blocks from the NN, and generating metadata recovery information of each of the data blocks according to the metadata of each of the data blocks, Thereby the metadata recovery information can be sent to at least one of the plurality of DNs. Such metadata recovery information can be used to be saved by the at least one DN and sent to the NN for recovery of the metadata after an exception occurs in the NN. Therefore, when the NN is abnormal, the metadata generated by the NN when an abnormality occurs can be restored in time.

Referring to FIG. 5, FIG. 5 is a schematic flowchart of another metadata recovery method according to an embodiment of the present invention. As shown in FIG. 5, the method includes the following steps:

501. Receive metadata recovery information of the target file sent by the client, and save the metadata recovery information, where the metadata recovery information is that the client receives the write operation request for the target file from the NN. Obtaining metadata of the target file, and recovering information according to the metadata generated by the metadata.

The target file of the target file is saved on multiple DNs, and the metadata includes information of the plurality of DNs.

Optionally, step 501 may be to store the metadata recovery information locally, or store the metadata recovery information on the third aspect storage device.

502. After the NN is abnormal, send the metadata recovery information to the NN, where the metadata recovery information is used by the NN to perform recovery of the metadata.

Optionally, the method can be applied to the DN of the HDFS.

In the above technical solution, the metadata recovery information of the target file sent by the client is received, and the metadata recovery information is saved; after the NN is abnormal, the metadata recovery information is sent to the NN, and the metadata recovery is performed. Information is used by the NN to perform recovery of the metadata. Thereby, it is possible to restore the metadata when the NN is abnormal.

Referring to FIG. 6, FIG. 6 is a schematic flowchart of another metadata recovery method according to an embodiment of the present invention. As shown in FIG. 6, the method includes the following steps:

601. Receive metadata recovery information of a data block of the target file sent by the client, and save the metadata recovery information, where the metadata recovery information is that the client receives the target file. When the operation request is written, the client recovers the metadata according to the metadata generated by the metadata of the data block.

The object file is divided into a plurality of data blocks, and the metadata of each of the data blocks includes information of each data block and information of a DN of each of the data blocks.

Optionally, the metadata recovery information received in step 601 may be metadata recovery information of one or more data blocks. For example, the target file is divided into a plurality of data blocks, wherein the DN performing the method may be metadata recovery information for storing one or more of the data blocks.

Optionally, step 601 is to save the foregoing metadata recovery information in a specific file, for example, in a file named: blk_blockId_genstamp.blockmeta, where the name of the file may include an identifier of the data block, and the The file name may also include a time stamp of the data block. For example, the DN may receive the identifier of the data sent by the client and the time stamp of the data block while receiving the metadata recovery information of the data block. In addition, the file may also save the data of the target file written by the client in the above data block to another specific file, for example, in a file named: blk_blockId. When the client also writes a Cyclic Redundancy Check (CRC) of the above data block, the method may also save the CRC for storing the metadata in the specific file of the metadata recovery information, that is, the metadata. The recovery information and CRC are stored in the same specific file. Of course, the method can also store the CRC in a specific file dedicated to storing the CRC. In addition, the two specific files may be set before receiving the data information, for example, when the write request sent by the client is received, the two specific files are generated. Since step 601 stores the above data information in the form of a file, this It can implement data warehouse workers (for example: Hive) or Spark functions. Spark is an open source cluster computing system based on memory computing, which aims to make data analysis faster.

In addition, the metadata recovery information may also be saved in a predefined data format, for example, in a HBase data format, where HBase is a distributed, column-oriented open source database.

Optionally, when the metadata recovery information is obtained, the metadata recovery information may also be saved in the memory, so that the metadata recovery information may be sent more quickly. The metadata recovery information of the memory can be directly uploaded to the NN. In addition, after the DN of the method is restarted, the locally stored metadata recovery information may be scanned, and the metadata recovery information is uploaded to the NN.

602. After the NN is abnormal, send the metadata recovery information to the NN, where the metadata recovery information is used by the NN to perform metadata recovery of the target file.

For example, when the DN is restarted, the DN receives a notification message sent by the NN, and the notification message is used to request to send the data information, so that the message notification message can be returned to return the metadata recovery information.

Optionally, the receiving, by the receiving, the metadata recovery information of the data block of the target file sent by the client includes:

Optionally, the received metadata recovery information may include at least metadata recovery information of the first data block and metadata recovery information of the second data block, where:

The metadata recovery information of the first data block may include:

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

In addition, in this embodiment, after the generated metadata is abnormal, the metadata recovery information of all the data blocks of the target file may be sent to the NN. For example, when the DN receives the notification message of the NN abnormal restart, the DN scans the metadata recovery information of all the data blocks in the local or the memory in response to the notification message, and uploads the metadata recovery information of all the data blocks to the NN.

Optionally, the foregoing method may be applied to the DN of the HDFS, that is, the DN may implement the foregoing method.

In the above technical solution, the metadata recovery information of the data block of the target file sent by the client is received, and the metadata recovery information is saved, and after the abnormality occurs in the NN, the element is sent to the NN. Data recovery information, the metadata recovery information is used by the NN to perform recovery of the metadata. Thereby, the metadata generated by the NN when an abnormality occurs can be restored in time.

Referring to FIG. 7, FIG. 7 is a schematic flowchart of another metadata recovery method according to an embodiment of the present invention. As shown in FIG. 7, the method includes the following steps:

701. Receive a write operation request to the target file sent by the client, where the target file is saved on multiple DNs.

702. Generate metadata of the target file, and send the metadata to the client, where the metadata includes information of the multiple DNs.

Optionally, in step 702, after receiving the foregoing write operation request, the multiple DNs are allocated to the target file, and the metadata of the target file is generated.

703. Receive metadata recovery information sent by at least one of the multiple DNs when an abnormality occurs on the local end, and recover the metadata according to the metadata recovery information, where the metadata recovery information is Generated by the client according to the metadata, sent by the client to The at least one DN performs the saved metadata recovery information.

In this way, when the local end, that is, the NN is abnormal, the metadata recovery information sent by the at least one DN can be received, so that the metadata of the target file can be recovered.

Optionally, the foregoing target file may be divided into multiple data blocks, where the multiple data blocks are saved on the multiple DNs;

Then, generating the metadata of the target file and sending the metadata to the client may include:

Generating metadata of the plurality of data blocks, and transmitting metadata of the plurality of data blocks to the client, where metadata of each data block includes information of each data block and where each of the data blocks is located DN information.

The receiving the metadata recovery information sent by the at least one of the plurality of DNs, and recovering the metadata according to the metadata recovery information, may include:

This makes it possible to recover the metadata of the target file based on the metadata recovery information of the plurality of data blocks.

Optionally, sending the metadata of the multiple data blocks to the client includes:

Optionally, the foregoing multiple data blocks may include at least a first data block and a second data block, where:

The metadata recovery information of the first data block may include:

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

It should be noted that, for the definition of the metadata and the metadata recovery information in this embodiment, reference may be made to the embodiment shown in FIG. 2 or FIG. 3, which is not repeatedly described herein.

Optionally, the above method can be applied to the NN in the HDFS.

In the above technical solution, the receiving client sends a write operation request to the target file, generates metadata of the target file, and sends the metadata to the client; Metadata recovery information transmitted by at least one of the plurality of DNs, and recovering the metadata according to the metadata recovery information. Thereby, the metadata when the NN is abnormal can be restored.

The following is a device embodiment of the present invention. The device embodiment of the present invention is used to perform the method implemented in Embodiments 1 to 5 of the method of the present invention. For the convenience of description, only parts related to the embodiment of the present invention are shown, and the specific technical details are not disclosed. Please refer to Embodiment 1, Example 2, Embodiment 3, Embodiment 4 and Embodiment 5 of the present invention.

Referring to FIG. 8, FIG. 8 is a schematic structural diagram of a client according to an embodiment of the present invention. As shown in FIG. 8, the method includes: a receiving unit 81, an obtaining unit 82, a generating unit 83, and a sending unit 84, where:

The receiving unit 81 is configured to receive a write operation request for the target file, where the target file is saved on multiple DNs.

The obtaining unit 82 is configured to acquire metadata of the target file from an NN, where metadata of the target file includes information of the plurality of DNs.

The generating unit 83 is configured to generate a metadata recovery signal according to the metadata of the target file. interest.

The sending unit 84 is configured to send the metadata recovery information to at least one of the plurality of DNs, where the metadata recovery information is used to be saved by the at least one DN, and appears in the NN The exception is sent to the NN for recovery of the metadata.

In another embodiment, the target file is divided into a plurality of data blocks, and the plurality of data blocks are saved on the plurality of DNs;

Then, the obtaining unit 82 may be configured to acquire metadata of the plurality of data blocks from the NN, where metadata of each data block includes information of each data block and information of a DN where each of the data blocks is located;

The generating unit 83 may be configured to generate metadata recovery information of each of the data blocks according to the metadata of each of the data blocks.

In this embodiment, metadata recovery information for generating each data block may be implemented such that the NN restores the metadata of the target file according to the metadata recovery information of the plurality of data blocks.

Optionally, the obtaining unit 82 may be configured to sequentially receive metadata of each of the data blocks sent by the NN; or the acquiring unit 82 may be configured to receive the NN according to the target file. The metadata of all data blocks that are requested to be sent at one time.

Optionally, the received metadata may include at least metadata of the first data block and metadata of the second data block, where:

The generated metadata recovery information of the first data block may include:

The generated metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

Optionally, the client may be an HDFS client.

Referring to FIG. 9, FIG. 9 is a schematic structural diagram of a DN according to an embodiment of the present invention. As shown in FIG. 9, the method includes: a receiving unit 91 and a sending unit 92, where:

The receiving unit 91 is configured to receive metadata recovery information of the target file sent by the client, and save the metadata recovery information, where the metadata recovery information is that the client receives a write operation request for the target file. At the time, the metadata of the object file acquired from the NN, and the metadata recovery information generated from the metadata.

The sending unit 92 is configured to send the metadata recovery information to the NN after the NN is abnormal, and the metadata recovery information is used by the NN to perform recovery of the metadata.

In another embodiment, the target file is divided into a plurality of data blocks, and the receiving unit 91 may be configured to receive metadata recovery information of the data block of the target file sent by the client, where the data The metadata recovery information of the block is metadata recovery information generated by the client according to the metadata of the data block.

Optionally, the receiving unit 91 may be configured to sequentially receive metadata recovery information of multiple data blocks of the target file sent by the client endpoint; or the receiving unit 91 may be configured to receive the client for one time. Metadata recovery information of a plurality of data blocks of the target file transmitted.

The metadata recovery information of the first data block may include:

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

Optionally, the node can be the DN of the HDFS.

Referring to FIG. 10, FIG. 10 is a schematic structural diagram of a NN according to an embodiment of the present invention. As shown in FIG. 10, the method includes: a receiving unit 101, a generating unit 102, and a restoring unit 103, where:

The receiving unit 101 is configured to receive a write operation request for the target file sent by the client, where the target file is saved on multiple DNs.

The generating unit 102 is configured to generate metadata of the target file, and send the metadata to the client, where the metadata includes information of the multiple DNs.

The recovery unit 103 is configured to receive metadata recovery information sent by at least one of the plurality of DNs when an abnormality occurs on the local end, and recover the metadata according to the metadata recovery information, where The metadata recovery information is generated by the client according to the metadata, and is sent by the client to the at least one DN for saving metadata recovery information.

The generating unit 102 may be configured to generate metadata of the plurality of data blocks, and send metadata of the plurality of data blocks to the client, where metadata of each data block includes each data block Information and information about the DN of each of the data blocks;

The recovery unit 103 may be configured to receive metadata recovery information of the plurality of data blocks sent by at least one of the plurality of DNs when an abnormality occurs on the local end, and according to the elements of the multiple data blocks. The data recovery information restores the metadata of the target file.

Optionally, the generating unit 102 may be configured to generate metadata of the multiple data blocks, and sequentially send metadata of the multiple data blocks to the client; or, the generating unit 102 may be configured to generate Metadata of the plurality of data blocks, and transmitting metadata of all data blocks to the client at a time according to a write operation request of the target file.

The metadata recovery information of the first data block may include:

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

Optionally, the foregoing node may be an NN in the HDFS.

Referring to FIG. 11, FIG. 11 is a schematic structural diagram of another metadata recovery device according to an embodiment of the present invention, including at least one processor 1102 (for example, a CPU), at least one network interface 1105 or other communication interface, a memory 1106, and At least one communication bus 1103 for implementing this Connection communication between these devices. The processor 1102 is configured to execute executable modules, such as computer programs, stored in the memory 1106. The memory 1106 may include a high speed random access memory (RAM), and may also include a non-volatile memory such as at least one disk memory. The communication connection between the system gateway and at least one other network element is implemented by at least one network interface 1105 (which may be wired or wireless), and may use an Internet, a wide area network, a local network, a metropolitan area network, or the like.

In some embodiments, the memory 1106 stores a program 11061 that can be executed by the processor 1102. This program includes:

In another embodiment, the object file may be divided into a plurality of data blocks, the plurality of data blocks may be saved on the plurality of DNs; and the processor 1102 performs the acquisition of the target file from the NN. The metadata, the program for generating the metadata recovery information according to the metadata of the target file, may include:

Optionally, the metadata executed by the processor 1102 is used to acquire the metadata of the multiple data blocks from the NN. The program can include:

Location information of the second data block in the target file.

Optionally, the device may be a device to which the client of the HDFS belongs.

In the above technical solution, receiving a write operation request for the target file; acquiring metadata of the target file from the NN; generating metadata recovery information according to the metadata of the target file; and at least one DN of the plurality of DNs Sending the metadata recovery information. Thus, the metadata recovery information can be used to be saved by the at least one DN, and after the NN has an abnormality, it is sent to the NN to recover the metadata, so that the metadata when the NN is abnormal can be restored.

Referring to FIG. 12, FIG. 12 is a schematic structural diagram of a DN device according to an embodiment of the present invention, including at least one processor 1202 (for example, a CPU), at least one network interface 1205 or other communication interface, a memory 1206, and at least one communication. Bus 1203 is used to implement connection communication between these devices. The processor 1202 is configured to execute executable modules, such as computer programs, stored in the memory 1206. The memory 1206 may include a high speed random access memory (RAM), and may also include a non-volatile memory such as at least one disk memory. Through at least one network interface 1205 (can be wired or not Line) realizes the communication connection between the system gateway and at least one other network element, and can use the Internet, a wide area network, a local network, a metropolitan area network, and the like.

In some embodiments, the memory 1206 stores a program 12061 that can be executed by the processor 1202. The program includes:

In another embodiment, the target file is divided into a plurality of data blocks, and the program executed by the processor 1202 to receive the metadata recovery information of the target file sent by the client may include:

Optionally, the program that is executed by the processor 1202 to receive the metadata recovery information of the data block of the target file that is sent by the client may include:

The metadata recovery information of the first data block may include:

Attribute information of the target file and a location of the first data block in the target file information;

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

Optionally, the device of the local node may be the device to which the DN of the HDFS belongs.

Referring to FIG. 13, FIG. 13 is a schematic structural diagram of an NN device according to an embodiment of the present invention, including at least one processor 1302 (eg, a CPU), at least one network interface 1305 or other communication interface, a memory 1306, and at least one communication. A bus 1303 is used to implement connection communication between these devices. The processor 1302 is configured to execute executable modules, such as computer programs, stored in the memory 1306. The memory 1306 may include a high speed random access memory (RAM) and may also include a non-volatile memory such as at least one disk memory. The communication connection between the system gateway and at least one other network element is implemented by at least one network interface 1305 (which may be wired or wireless), and may use an Internet, a wide area network, a local network, a metropolitan area network, or the like.

In some embodiments, the memory 1306 stores a program 13061 that can be executed by the processor 1302. This program includes:

In another embodiment, the object file is divided into a plurality of data blocks, the plurality of data blocks are saved on the plurality of DNs; the processor 1302 performs metadata generation of the object file, and Sending the metadata to the client may include:

The program executed by the processor 1302, which receives the metadata recovery information sent by the at least one of the plurality of DNs, and recovers the metadata according to the metadata recovery information, may include:

Optionally, the program executed by the processor 1302 to send the metadata of the multiple data blocks to the client may include:

The metadata recovery information of the first data block may include:

The metadata recovery information of the second data block may include:

Location information of the second data block in the target file.

Optionally, the foregoing node device may be a device to which the NN in the HDFS belongs.

In the above technical solution, the receiving client sends a write operation request to the target file; generating metadata of the target file, and sending the metadata to the client; and when the local end is abnormal, receiving the multiple Metadata recovery information transmitted by at least one of the DNs, and the metadata is restored according to the metadata recovery information. Thereby, the metadata when the NN is abnormal can be restored.

One of ordinary skill in the art can understand that all or part of the process of implementing the foregoing embodiments can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and thus equivalent changes made in the claims of the present invention are still within the scope of the present invention.

Claims

A metadata recovery method, comprising:

Receiving a write operation request to the target file, wherein the target file is saved on a plurality of data nodes;

Obtaining metadata of the target file from a metadata node, where metadata of the target file includes information of the plurality of data nodes;

Generating metadata recovery information according to metadata of the target file;

Transmitting the metadata recovery information to at least one of the plurality of data nodes, the metadata recovery information being used for being saved by the at least one data node, and being Sending to the metadata node for recovery of the metadata.
The method of claim 1, wherein the object file is divided into a plurality of data blocks, the plurality of data blocks being stored on the plurality of data nodes;

Then, the acquiring the metadata of the target file from the metadata node, and generating the metadata recovery information according to the metadata of the target file includes:

Obtaining metadata of the plurality of data blocks from the metadata node, the metadata of each data block includes information of each data block and information of a data node where each of the data blocks is located;

Generating metadata recovery information for each of the data blocks based on the metadata of each of the data blocks.
The method of claim 2, wherein the obtaining metadata of the plurality of data blocks from the metadata node comprises:

Receiving metadata of each of the data blocks sent by the metadata node in sequence; or receiving metadata of all data blocks that are sent by the metadata node in one time according to a write operation of the target file.
The method according to claim 2 or 3, wherein the received metadata includes at least metadata of the first data block and metadata of the second data block, wherein:

The generated metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The generated metadata recovery information of the second data block includes:

Location information of the second data block in the target file.
A metadata recovery method, comprising:

Receiving metadata recovery information of the target file sent by the client, and saving the metadata recovery information, wherein the metadata recovery information is from the metadata node when the client receives a write operation request for the target file Obtaining metadata of the target file, and recovering information according to the metadata generated by the metadata.

After the metadata node is abnormal, the metadata recovery information is sent to the metadata node, and the metadata recovery information is used by the metadata node to perform recovery of the metadata.
The method of claim 5, wherein the target file is divided into a plurality of data blocks, and the metadata recovery information of the target file sent by the receiving client comprises:

And receiving metadata recovery information of the data block of the target file sent by the client, where the metadata recovery information of the data block is metadata recovery information generated by the client according to the metadata of the data block.
The method of claim 6, wherein the receiving the metadata recovery information of the data block of the target file sent by the client comprises:

Receiving metadata recovery information of the plurality of data blocks of the target file sent by the client endpoint in sequence; or receiving metadata recovery information of the plurality of data blocks of the target file sent by the client at one time.
The method according to claim 6 or 7, wherein the received metadata recovery information comprises at least metadata recovery information of the first data block and metadata recovery information of the second data block, wherein:

The metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.
A metadata recovery method, comprising:

Receiving a write operation request to the target file sent by the client, where the target file is saved on multiple data nodes;

Generating metadata of the object file and transmitting the metadata to the client, wherein the metadata includes information of the plurality of data nodes;

Receiving metadata recovery information sent by at least one of the plurality of data nodes when an abnormality occurs at the local end, and recovering the metadata according to the metadata recovery information, wherein the metadata recovery information is The metadata recovery information generated by the client according to the metadata and sent by the client to the at least one data node for saving.
The method of claim 9, wherein the object file is divided into a plurality of data blocks, the plurality of data blocks being stored on the plurality of data nodes;

And generating the metadata of the target file, and sending the metadata to the client includes:

Generating metadata of the plurality of data blocks, and transmitting metadata of the plurality of data blocks to the client, where metadata of each data block includes information of each data block and where each of the data blocks is located Information of the data node;

Receiving the metadata recovery information sent by the at least one of the plurality of data nodes, and recovering the metadata according to the metadata recovery information, including:

Receiving metadata recovery information of the plurality of data blocks sent by at least one of the plurality of data nodes, and recovering metadata of the target file according to metadata recovery information of the plurality of data blocks.
The method of claim 10 wherein said sending to said client The metadata of the plurality of data blocks includes:

Transmitting metadata of the plurality of data blocks to the client in turn; or sending metadata of all data blocks to the client at a time according to a write operation request of the target file.
The method according to claim 10 or 11, wherein said plurality of data blocks comprises at least a first data block and a second data block, wherein:

The metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.
A client, comprising: a receiving unit, an obtaining unit, a generating unit, and a sending unit, wherein:

The receiving unit is configured to receive a write operation request for the target file, where the target file is saved on multiple data nodes;

The acquiring unit is configured to acquire metadata of the target file from a metadata node, where metadata of the target file includes information of the plurality of data nodes;

The generating unit is configured to generate metadata recovery information according to metadata of the target file;

The sending unit is configured to send the metadata recovery information to at least one of the plurality of data nodes, where the metadata recovery information is used to be saved by the at least one data node, and in the After the metadata node has an abnormality, it is sent to the metadata node for recovery of the metadata.
The client according to claim 13, wherein the object file is divided into a plurality of data blocks, and the plurality of data blocks are saved on the plurality of data nodes;

Then, the obtaining unit is configured to acquire metadata of the plurality of data blocks from the metadata node, where metadata of each data block includes information of each data block and a data node where each of the data blocks is located Information;

The generating unit is configured to generate metadata recovery information of each of the data blocks according to the metadata of each of the data blocks.
The client according to claim 14, wherein the obtaining unit is configured to sequentially receive metadata of each of the data blocks sent by the metadata node; or the acquiring unit is configured to receive the The metadata node requests metadata of all data blocks that are sent at one time according to a write operation of the target file.
The client according to claim 14 or 15, wherein the received metadata includes at least metadata of the first data block and metadata of the second data block, wherein:

The generated metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The generated metadata recovery information of the second data block includes:

Location information of the second data block in the target file.
A data node, comprising: a receiving unit and a sending unit, wherein:

The receiving unit is configured to receive metadata recovery information of the target file sent by the client, and save the metadata recovery information, where the metadata recovery information is that the client receives a write operation on the target file. At the time of request, the metadata of the object file acquired from the metadata node, and the metadata recovery information generated according to the metadata.

The sending unit is configured to send the metadata recovery information to the metadata node after an abnormality occurs in the metadata node, where the metadata recovery information is used by the metadata node to perform recovery of the metadata .
The data node according to claim 17, wherein the object file is divided into a plurality of data blocks, and the receiving unit is configured to receive metadata recovery of the data block of the target file sent by the client. Information, the metadata recovery information of the data block is metadata recovery information generated by the client according to metadata of the data block.
A data node according to claim 18, wherein said receiving unit is for Receiving, in sequence, metadata recovery information of the plurality of data blocks of the target file sent by the client endpoint; or, the receiving unit is configured to receive, by the client, a plurality of data blocks of the target file that are sent by the client at one time Metadata recovery information.
The data node according to claim 17 or 18, wherein said received metadata recovery information comprises at least metadata recovery information of said first data block and metadata recovery information of said second data block, wherein:

The metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.
A metadata node, comprising: a receiving unit, a generating unit, and a restoring unit, wherein:

The receiving unit is configured to receive a write operation request for the target file sent by the client, where the target file is saved on multiple data nodes;

The generating unit is configured to generate metadata of the target file, and send the metadata to the client, where the metadata includes information of the multiple data nodes;

The recovery unit is configured to receive metadata recovery information sent by at least one of the plurality of data nodes when an abnormality occurs on the local end, and recover the metadata according to the metadata recovery information, where The metadata recovery information is metadata recovery information that is generated by the client according to the metadata and sent by the client to the at least one data node for saving.
The metadata node according to claim 21, wherein said object file is divided into a plurality of data blocks, said plurality of data blocks being stored on said plurality of data nodes;

The generating unit is configured to generate metadata of the plurality of data blocks, and send metadata of the plurality of data blocks to the client, where metadata of each data block includes information of each data block And information of the data node where each of the data blocks is located;

The recovery unit is configured to receive metadata recovery information of the plurality of data blocks sent by at least one of the plurality of data nodes when an abnormality occurs on the local end, and according to the elements of the multiple data blocks The data recovery information restores the metadata of the target file.
The metadata node according to claim 21, wherein the generating unit is configured to generate metadata of the plurality of data blocks, and sequentially send metadata of the plurality of data blocks to the client; Alternatively, the generating unit is configured to generate metadata of the plurality of data blocks, and send metadata of all data blocks to the client at one time according to a write operation request of the target file.
The metadata node according to claim 10 or 11, wherein said plurality of data blocks comprises at least a first data block and a second data block, wherein:

The metadata recovery information of the first data block includes:

Attribute information of the target file and location information of the first data block in the target file;

The metadata recovery information of the second data block includes:

Location information of the second data block in the target file.