Backing Up ClickHouse Metadata

Scenario

To ensure ClickHouse metadata security or before a major operation (such as upgrade or migration), you need to back up ClickHouse metadata. The backup data can be used to recover the system if an exception occurs or the operation has not achieved the expected result, minimizing the adverse impacts on services.

You can create a backup task on FusionInsight Manager to back up ClickHouse metadata. Both automatic and manual backup tasks are supported.

This function is supported only by MRS 3.1.0 or later.

Prerequisites

• To back up data to a remote HDFS, the following conditions must be met:
  • A standby cluster for backing up data has been created. The authentication mode must be the same as that of the active cluster.
  • If the active cluster is deployed in security mode and the active and standby clusters are not managed by the same FusionInsight Manager, mutual trust has been configured. For details, see Configuring Mutual Trust Between MRS Clusters. If the active cluster is deployed in normal mode, no mutual trust is required.
  • Time is consistent between the active and standby clusters and the NTP services on the active and standby clusters use the same time source.
  • In active/standby mode, ensure that the value of HADOOP_RPC_PROTECTION of ClickHouse is the same as that of hadoop.rpc.protection of HDFS.

• The backup type, period, policy, and other specifications have been planned based on the service requirements and you have checked whether Data storage path/LocalBackup/ has sufficient space on the active and standby management nodes.

Backing Up ClickHouse Metadata

1. On FusionInsight Manager, choose O&M > Backup and Restoration > Backup Management.
2. Click Create.
3. Set Name to the name of the backup task.
4. Select the cluster to be operated from Backup Object.
5. Set Mode to the type of the backup task. Periodic indicates that the backup task is periodically executed. Manual indicates that the backup task is manually executed.
   To create a periodic backup task, set the following parameters:

   • Started: indicates the time when the task is started for the first time.
   • Period: indicates the task execution interval. The options include Hours and Days.
   • Backup Policy: Only Full backup every time is supported.

6. In Configuration, select ClickHouse under Metadata and other data.
7. Set Path Type of ClickHouse to a backup directory type.
   The following backup directory types are supported:

   • LocalDir: indicates that the backup files are stored on the local disk of the active management node and the standby management node automatically synchronizes the backup files.

     The default storage directory is Data storage path/LocalBackup/, for example, /srv/BigData/LocalBackup.

     If you select this option, you need to set the maximum number of replicas to specify the number of backup file sets that can be retained in the backup directory.

   • RemoteHDFS: indicates that the backup files are stored in the HDFS directory of the standby cluster.

     This option is available for MRS 3.1.0 and 3.1.2 clusters only after you configure the environment by referring to Configuring the Environment When the ClickHouse Backup Task's Path is RemoteHDFS.

     You also need to configure the following parameters for MRS 3.2.0 or later clusters:

     • Destination NameService Name: indicates the NameService name of the standby cluster, for example, hacluster. You can obtain it from the NameService Management page of HDFS of the standby cluster.

     • IP Mode: indicates the mode of the target IP address. The system automatically selects the IP address mode based on the cluster network type, for example, IPv4 or IPv6.
     • Destination Active NameNode IP Address: indicates the service plane IP address of the active NameNode in the standby cluster.
     • Destination Standby NameNode IP Address: indicates the service plane IP address of the standby NameNode in the standby cluster.
     • Destination NameNode RPC Port: indicates the value of dfs.namenode.rpc.port in the HDFS basic configuration of the destination cluster.
     • Target Path: indicates the HDFS directory for storing standby cluster backup data. The storage path cannot be an HDFS hidden directory, such as a snapshot or recycle bin directory, or a default system directory, such as /hbase or /user/hbase/backup.
     You also need to configure the following parameters for MRS 3.1.0 or 3.1.2 clusters:

     • Destination NameService Name: indicates the NameService name of the standby cluster, for example, hacluster. You can obtain it from the NameService Management page of HDFS of the standby cluster.

     • IP Mode: indicates the mode of the target IP address. The system automatically selects the IP address mode based on the cluster network type, for example, IPv4 or IPv6.
     • Target NameNode IP Address: indicates the IP address of the NameNode service plane in the standby cluster. It can be of an active or standby node.
     • Target Path: indicates the HDFS directory for storing standby cluster backup data. The storage path cannot be an HDFS hidden directory, such as a snapshot or recycle bin directory, or a default system directory, such as /hbase or /user/hbase/backup.
     • Maximum Number of Backup Copies: indicates the number of backup file sets that can be retained in the backup directory.

8. Click OK.
9. In the Operation column of the created task in the backup task list, click More and select Back Up Now to execute the backup task.

   After the backup task is executed, the system automatically creates a subdirectory for each backup task in the backup directory. The format of the subdirectory name is Backup task name_Task creation time, and the subdirectory is used to save data source backup files. The format of the backup file name is Data source_Task execution time.tar.gz.

Configuring the Environment When the ClickHouse Backup Task's Path is RemoteHDFS

This topic is available for MRS 3.1.0 and 3.1.2 only.

1. Log in to FusionInsight Manager of the standby cluster.
2. Choose Cluster > Services > HDFS. Click More and select Download Client. Set Select Client Type to Configuration Files Only, select x86_64 for x86 or aarch64 for Arm based on the type of the node, and click OK.
3. After the client file package is generated, download the client to the local PC as prompted and decompress the package.

   For example, if the client file package is FusionInsight_Cluster_1_HDFS_Client.tar, decompress it to obtain FusionInsight_Cluster_1_HDFS_ClientConfig_ConfigFiles.tar. Then, decompress this file to the D:\FusionInsight_Cluster_1_HDFS_ClientConfig_ConfigFiles directory on the local PC. The directory name cannot contain spaces.

4. Go to the FusionInsight_Cluster_1_HDFS_ClientConfig_ConfigFiles\ client directory and obtain the hosts file.
5. Go to FusionInsight_Cluster_1_HDFS_ClientConfig_ConfigFiles\HDFS\config to obtain the core-site.xml and hdfs-site.xml files.
6. Log in to FusionInsight Manager of the source cluster.
7. Choose Cluster > Services > ClickHouse, choose Configurations > All Configurations, and select backup under ClickHouse(Service).

   For remote_connect_core_config_file, click Upload File and select the core-site.xml file prepared in 5.

   For remote_connect_hdfs_config_file, click Upload File and select the hdfs-site.xml file prepared in 5.

   Figure 1 Configuring ClickHouse data backup parameters
   

8. Click Save, confirm the information, and click OK to save the configuration. After saving the configurations, click Finish.
9. Choose Cluster > Services > ClickHouse, click Instances, and view the instance IP address of ClickHouseServer.
10. Log in to the host nodes of the ClickHouseServer instances as user root and check whether the /etc/hosts file contains the host information in 4. If not, add the host information in 4 to the /etc/hosts file.