Recovering Yarn Data

Scenario

MRS cluster administrators can create a recovery task in FusionInsight Manager to recover Yarn metadata. Only manual recovery tasks are supported.

• Data recovery can be performed only when the system version is consistent with that of data backup.
• To recover data when the service is running properly, you are advised to manually back up the latest management data before recovering data. Otherwise, the data that is generated after the data backup and before the data recovery will be lost.
• It is recommended that a data restoration task restore the metadata of only one component to prevent the data restoration of other components from being affected by stopping a service or instance. If data of multiple components is restored at the same time, data restoration may fail.

Impact on the System

• Resource pool information is also stored in DBService. Therefore, when restoring Yarn data, you need to manually trigger the restoration of the DBService data backed up at the corresponding time. If only Yarn data is restored, the Yarn data stored in ZooKeeper is inconsistent with that stored in DBService. As a result, the Yarn resource pool is abnormal. Exercise caution when performing this operation and ensure that the Yarn data to be restored is consistent with the DBService data.
• Before recovering metadata, you need to stop the Yarn service, during which the Yarn upper-layer applications are unavailable.
• After the metadata is recovered, the data produced between the backup time and restoration time is lost.
• After the metadata is recovered, the Yarn upper-layer applications need to be started.

Prerequisites

• If the active cluster employs the security mode, cross-cluster trust relationship has been configured for the active and standby clusters. For details, see Configuring Cross-Manager Cluster Mutual Trust Relationships. If the active cluster employs the normal mode, no cross-cluster trust relationship is required.
• Cross-cluster replication has been configured for the active and standby clusters. For details, see Enabling Cross-Cluster Replication.
• Check the directory for saving the Yarn backup file.
• Stop the Yarn upper-layer applications.
• You have logged in to FusionInsight Manager. For details, see Logging In to FusionInsight Manager.

Procedure

1. On FusionInsight Manager, choose O&M > Backup and Restoration > Backup Management.
2. In the Operation column of a specified task in the task list, click More > View History to view historical backup task execution records.

   In the displayed window, locate a specified success record and click View in the Backup Path column to view the backup path information of the task and find the following information:

   • Backup Object specifies the data source of the backup data.
   • Backup Path specifies the full path where the backup files are saved.

     Select the correct item, and manually copy the full path of backup files in Backup Path.

3. On FusionInsight Manager, choose O&M > Backup and Restoration > Restoration Management.
4. Click Create.
5. Set Task Name to the name of the recovery task.
6. Select the cluster to be operated from Recovery Object.
7. In Restoration Configuration, select Yarn and DBService under Metadata and other data.
   

   Resource pool information is also stored in DBService. Therefore, when restoring Yarn data, you need to manually trigger the restoration of the DBService data backed up at the corresponding time. If only Yarn data is restored, the Yarn data stored in ZooKeeper is inconsistent with that stored in DBService. As a result, the Yarn resource pool is abnormal. Exercise caution when performing this operation and ensure that the Yarn data to be restored is consistent with the DBService data.

8. Set Path Type of DBService to a backup directory type. For details, see Recovering DBService Data
9. Set Path Type of Yarn 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. If you select this value, you need to set Source Path to select the backup file, for example, version_data source_task execution time.tar.gz.
   • RemoteHDFS: indicates that the backup files are stored in the HDFS directory of the standby cluster. If you select this value, you need to set the following parameters:
     • Source NameService Name: indicates the NameService name of the backup data cluster. You can set it to the NameService name (haclusterX, haclusterX1, haclusterX2, haclusterX3, or haclusterX4) of the built-in remote cluster of the cluster, or the NameService name of a configured remote cluster.
     • IP Mode: 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.
     • Source NameNode IP Address: indicates the NameNode service plane IP address of the standby cluster, supporting the active node or standby node.
     • Source Path: indicates the full path of the HDFS directory for storing standby cluster backup data. For example, backup path/backup task name_data source_task creation time/version_data source_task execution time.tar.gz.
     • Queue Name: indicates the name of the YARN queue used for backup task execution.
   • NFS: indicates that backup files are stored in the NAS over the NFS protocol.
     If you select NFS, set the following parameters:

     • IP Mode: 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.

     • Server IP address: indicates the NAS server IP address.
     • Source Path: indicates the complete path of the backup file on the NAS server. For example, backup path/backup task name_data source_task creation time/version_data source_task execution time.tar.gz.
   • CIFS: indicates that backup files are stored in the NAS over the CIFS protocol.
     If you select CIFS, set the following parameters:

     • IP Mode: 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.

     • Server IP address: indicates the NAS server IP address.
     • Port: indicates the port ID used by the CIFS protocol to connect to the NAS server. The default value is 445.
     • Username: Indicates the user name that is configured when setting the CIFS protocol.
     • Password: indicates the password that is configured when setting the CIFS protocol.
     • Source Path: indicates the complete path of the backup file on the NAS server. For example, backup path/backup task name_data source_task creation time/version_data source_task execution time.tar.gz.
   • SFTP: Indicates that backup files are stored in the server using SFTP.
     If you select SFTP, set the following parameters:

     • IP Mode: 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.

     • Server IP address: Enter the IP address of the server where the backup data is stored.
     • Port: Enter the port number used by the SFTP protocol to connect to the backup server. The default value is 22.
     • Username: Enter the username for connecting to the server using SFTP.
     • Password: Enter the password for connecting to the server using SFTP.
     • Source Path: Enter the full path of the backup file on the backup server. For example, backup path/backup task name_data source_task creation time/version_data source_task execution time.tar.gz.
   • OBS: indicates that the backup files are stored in the OBS directory.
     If you select this value, you need to set the following parameters:

     • Source Path: indicates the full path for storing backup data in OBS. For example, backup path/backup task name_data source_task creation time/version_data source_task execution time.tar.gz.
       

       MRS 3.1.0 and later versions support saving backup files to OBS.

10. Click OK to save the settings.
11. In the recovery task list, locate a created task and click Start in the Operation column to execute the recovery task.
    • After the recovery is successful, the progress bar is in green.
    • After the recovery is successful, the recovery task cannot be executed again.
    • If the recovery task fails during the first execution, rectify the fault and click Retry to execute the task again.