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FusionInsight HD 6.5.0 Administrator Guide 02

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Recovering NameNode Data

Recovering NameNode Data

Scenario

NameNode data needs to be recovered in the following scenarios: HDFS metadata is modified or deleted unexpectedly and needs to be restored. After an administrator performs critical data adjustment in NameNode, an exception occurs or the operation has not achieved the expected result. All modules are faulty and become unavailable. Data is migrated to a new cluster.

System administrators can create a recovery task in FusionInsight Manager to recover NameNode data. 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 NameNode data that is generated after the data backup and before the data recovery will be lost.

Impact on the System

  • After the data is recovered, the data produced between the backup time and restoration time is lost.
  • After the data is recovered, the NameNode needs to be restarted and is unavailable during the restart.
  • After data is restored, metadata and service data may not be matched, HDFS enters the security mode, and the HDFS service cannot be started. For details, see HDFS Block Loss in Troubleshooting.

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-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.
  • The time of the active cluster and standby cluster must be the same, and the NTP service in the active and standby clusters must use the same time source.
  • You have logged in to FusionInsight Manager. For details, see Logging In to the Management System.
  • On FusionInsight Manager, all the NameNode role instances whose data is to be recovered are stopped. Other HDFS role instances must keep running. After data is recovered, the NameNode role instances need to be restarted. The NameNode role instances cannot be accessed during the restart.
  • The NameNode backup files are stored Data path/LocalBackup/ on the active management node.

Procedure

  1. Choose Cluster > Service > HDFS > Instance > NameNode to check whether the NameNode instances of the data to be restored are stopped. If the NameNode instances are not stopped, stop them.
  2. On FusionInsight Manager, choose O&M > Backup and Restoration > Backup Management.
  3. 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.

  4. On FusionInsight Manager, choose O&M > Backup and Restoration > Restoration Management.
  5. Click Create.
  6. Set Task Name to the name of the recovery task.
  7. Select NameNode.
  8. Set Path Type of NameNode to a backup directory type.

    The settings vary according to backup directory types:

    • 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 the following parameters:
      • Source Path: indicates the full path of the local disk 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.
      • Target NameService Name: indicates the target NameService that corresponds to the selected backup directory. The default value of this parameter is hacluster.
    • RemoteHDFS(DistCp): 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:
      • Target 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. The name must be the same as the name of the queue that is running properly in the cluster.
      • Target NameService Name: indicates the target NameService that corresponds to the selected backup directory. The default value of this parameter is hacluster.
    • NFS: indicates that backup files are stored in the NAS over the NFS protocol. If you select NFS, set the following parameters:
      • 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.
      • Target NameService Name: indicates the target NameService that corresponds to the selected backup directory. The default value of this parameter is hacluster.
    • CIFS: indicates that backup files are stored in the NAS over the CIFS protocol. If you select CIFS, set the following parameters:
      • 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.
      • Target NameService Name: indicates the target NameService that corresponds to the selected backup directory. The default value of this parameter is hacluster.

  9. Click OK to save the settings.
  10. 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.

  11. On FusionInsight Manager, choose Cluster > Service > HDFS > More > Restart.

    In the displayed window, enter the password of the current administrator and click OK. After the system displays "Operation succeeded", click Finish. The service is successfully started.

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Updated: 2019-05-17

Document ID: EDOC1100074522

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