Help Center/ MapReduce Service/ User Guide/ MRS Cluster O&M/ MRS Cluster Data Backup and Restoration/ Restoring MRS Cluster Component Data/ Restoring CDL Service Data
Updated on 2024-09-23 GMT+08:00
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Restoring CDL Service Data

Scenario

CDL data needs to be restored in the following scenarios: Data is modified or deleted unexpectedly and needs to be restored. After an administrator performs major operations (such as upgrade and data adjustment) on CDL, an exception occurs or the expected result is not achieved. All modules are faulty and become unavailable. Data is migrated to a new cluster.

CDL metadata is stored in DBService and Kafka. A system administrator can create DBService and Kafka restoration tasks on FusionInsight Manager to restore CDL data. Only manual restoration tasks are supported.

  • Data restoration can be performed only when the system version is consistent with that during data backup.
  • To restore the data when services are normal, manually back up the latest management data first and then restore the data. Otherwise, the DBService and Kafka data that is generated after the data backup and before the data restoration will be lost.
  • By default, MRS clusters use DBService to store metadata of Hive, Hue, Loader, Spark, CDL, and Oozie. Restoring DBService data will restore the metadata of all these components.

Impact on the System

  • After the data is restored, the data generated after the data backup and before the data restoration is lost.
  • After the data is restored, the configurations of the components that depend on DBService may expire and these components need to be restarted.
  • After the metadata is restored, the offset information stored on ZooKeeper by Kafka consumers is rolled back, resulting in repeated consumption.

Prerequisites

  • To restore data from a remote HDFS, the following conditions must be met:
    • A standby cluster for restoring data has been created, and data in this cluster has been backed up. For details, see Backing Up CDL Service Data. 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.
    • Cross-cluster replication has been configured for the active and standby clusters. For details, see Enabling MRS Inter-Cluster Replication.
    • Time is consistent between the active and standby clusters and the NTP services on the active and standby clusters use the same time source.
  • The status of the active and standby DBService instances is normal. If the status is abnormal, data restoration cannot be performed.
  • The Kafka service has been stopped. After the restoration is complete, start the Kafka service.

Restoring CDL Service Data

  1. On FusionInsight Manager, choose O&M > Backup and Restoration > Backup Management.
  2. In the row where the specified backup task is located, choose More > View History in the Operation column to display the historical execution records of the backup task.

    In the window that is displayed, select a success record and click View in the Backup Path column to view its backup path information and find the following information:

    • Backup Object: indicates the backup data source.
    • Backup Path: indicates the full path where backup files are stored.

      Select the correct path, 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 restoration task.
  6. Select the cluster to be operated from Recovery Object.
  7. In the Restoration Configuration area, select DBService and Kafka.
  8. Set Path Type of DBService to a backup directory type. For details about how to configure the parameters, see 8.
  9. Set Path Type of Kafka to a backup directory type. For details about how to configure the parameters, see 8.
  10. Click OK.
  11. In the restoration task list, locate the row where the created task is located, and click Start in the Operation column.

    • After the restoration is successful, the progress bar is in green.
    • After the restoration is successful, the restoration task cannot be executed again.
    • If the restoration task fails during the first execution, rectify the fault and click Retry to execute the task again.