Help Center > > User Guide> Managing an Existing Cluster> Component Management> Managing Services

Managing Services

Updated at: Oct 21, 2021 GMT+08:00

You can perform the following operations on MRS:

  • Add or delete services. Only MRS 3.1.2 and later versions support adding and deleting services.
  • Start the service in the Stopped, Stop Failed, or Failed to Start state to use the service.
  • Stop the services or stop abnormal services.
  • Restart abnormal services or configure expired services to restore or enable the services.

Prerequisites

  • You have synchronized IAM users (on the Dashboard page, click Synchronize on the right side of IAM User Sync to synchronize IAM users).
    Figure 1 Synchronizing IAM users
  • When adding a service, ensure that the role instances of the underlying services on which the service depends are running properly. Otherwise, the service may fail to be added or fail to be started after being added.

Impact on the System

  • When a service is being added or deleted, the cluster is no longer in the Running state. In this case, new jobs cannot be submitted on the Jobs page of the cluster.
  • The stateful component cannot be added to the task node group.

Adding a Service

  1. On the cluster details page, Choose Components and click Add Service.
  2. In the service list, select the services to be added and click Next.

    • When you add a service, the underlying services on which the service depends are automatically selected. You can add multiple services at the same time.
    • You can add a service only on a node in normal state.
    • For a cluster where the Hadoop service is not installed, you need to synchronize IAM users after adding the Hadoop service. For details, see Synchronizing IAM Users to MRS.
    • For a cluster where the Hadoop service is installed, you need to manually restore tenant data on the tenant side after deleting the Hadoop service and adding it again. For details, see Restoring Tenant Data.
    • For a cluster where Hadoop is installed, if you want to add a component after it is deleted from Hadoop, you must delete other Hadoop components and add Hadoop again. Hadoop contains the MapReduce, Yarn, and HDFS components.
    • A single component of the Hadoop service cannot be added to the cluster. Only the Hadoop service can be added. The Hadoop service includes MapReduce, Yarn, and HDFS.

  3. On the Topology Adjustment page, select the nodes where the service is to be deployed. For details about the deployment scheme, see Table 3.
  4. Click OK. After the service is added, you can view the added service on the Components page.

    The services added on the console are automatically synchronized to Manager.

Deleting a Service

  1. On the cluster details page, click Components.
  2. Locate the row that contains the target service and click Delete.

    • If the service to be deleted has upper-layer dependencies, the service cannot be deleted. Only one service can be deleted at a time.
    • You can delete other installed services except Yarn, HDFS, Ranger, MapReduce, DBService, KrbServer, LdapServer, and meta services.
    • For a cluster where Hadoop is installed, if you want to add a component after it is deleted from Hadoop, you must delete other Hadoop components and add Hadoop again. Hadoop contains the MapReduce, Yarn, and HDFS components.
    • If the Hadoop service in the cluster is in use and contains service data that cannot be deleted, you are not advised to delete Hadoop components.

  3. In the dialog box that is displayed, click Yes to confirm the deletion.

    • The services deleted on the console are automatically synchronized to Manager.
    • Before deleting a service, back up the service data to prevent data loss.

Other Operations

  1. On the MRS cluster details page, click Components.
  2. Locate the row that contains the target service, Start, Stop, and Restart to start, stop, or restart the service.

    Services are interrelated. If a service is started, stopped, and restarted, services dependent on it will be affected.

    The services will be affected in the following ways:

    • If a service is to be started, the lower-layer services dependent on it must be started first.
    • If a service is stopped, the upper-layer services dependent on it are unavailable.
    • If a service is restarted, the running upper-layer services dependent on it must be restarted.

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