Help Center/ MapReduce Service/ User Guide/ Managing Clusters/ Managing MRS Cluster Components/ Managing MRS Role Instances
Updated on 2026-10-09 GMT+08:00
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Managing MRS Role Instances

While an MRS cluster is running, you may need to manage the lifecycle of role instances. For example, if a role instance is in the Stopped, Failed to stop, or Failed to start state, start the role instance to restore the service. If a role instance is no longer used or is abnormal, stop or restart the role instance to release resources or restore functions. In addition, you can export and import configuration parameters of role instances to migrate or back up configuration data between clusters.

Prerequisites

  • The IAM users have been synchronized in advance. You can do this by clicking Synchronize next to IAM User Sync on the Dashboard page of the cluster details.
  • You have logged in to MRS Manager. For how to log in, see Accessing MRS Manager.

Managing Role Instances

Currently, you can manage instances on either the management console or MRS Manager.

On the MRS console, you can start, stop, restart, and perform a rolling restart on role instances.

  1. Log in to the MRS console.
  2. On the Active Clusters page, select a running target cluster and click its name to go to the cluster details page.
  3. On the cluster details page, click Components.
  4. Select the target service from the service list.
  5. Click the Instances tab.
  6. Select the check box on the left of the target role instance.
  7. Click More, select operations such as Start Instance, Stop Instance, Restart Instance, Rolling-restart Instance, or Delete Instance based on site requirements.

    A rolling restart means that instances are restarted one by one rather than simultaneously, preventing service interruption. For details about instance support for rolling restart and the relevant parameters, see Component Restart Reference Information.

On MRS Manager, you can start, stop, and restart role instances.

  1. Log in to FusionInsight Manager of the MRS cluster.

    For details about how to log in to FusionInsight Manager, see Accessing MRS Manager.

  2. Go to the service instance page.

    • MRS 3.x and later versions: Choose Cluster > Services, click the name of the target service, and click Instances.
    • MRS 2.x and earlier versions: Click Services and click Instances.

  3. Select the check box on the left of the target role instance.
  4. Choose More > Start Instance, Stop Instance, or Restart Instance as prompted.

    For details about instance support for rolling restart and the relevant parameters, see Component Restart Reference Information.

Exporting and Importing Role Instance Configurations

You can export the configuration parameters of a role instance to a local file or import them from a local file to a role instance, facilitating configuration backup, migration, and restoration.

For clusters of MRS 3.x and later

  1. Log in to FusionInsight Manager of the MRS cluster.

    For details about how to log in to FusionInsight Manager, see Accessing MRS Manager.

  2. Choose Cluster > Services and click the name of the service to be operated in the service view.
  3. Click Instances and click the instance to be operated.
  4. Click Instance Configuration and click Export to export the configuration parameter file to the local PC.
  5. On the Instance Configurations page, click Import, select the configuration parameter file of the instance, and import the file.

For MRS clusters of 2.x and earlier:

  1. Log in to FusionInsight Manager of the MRS cluster.

    For details about how to log in to FusionInsight Manager, see Accessing MRS Manager.

  2. Click Services.
  3. Select a service.
  4. Select a role instance or click Instances.
  5. Select a role instance on a specified host.
  6. Click Instance Configuration.
  7. Click Export Instance Configuration to export the configuration data of a specified role instance, and choose a path for saving the configuration file.
  8. Click Import Instance Configuration to import the configuration data of the specified role instance.

    Click Save Configuration and select Restart the role instance. Click OK.

    After the system displays "Operation succeeded", click Finish. The role instance is started.

Verifying Role Instance Status

After starting, stopping, restarting, or importing configurations of a role instance, verify the running status of the role instance to ensure that the operation has taken effect.

  • MRS console: On the cluster details page, choose Components > Service name > Instances to check the role instance status.
  • MRS Manager: Choose Cluster > Services > Instances to check whether the role instance is in the expected status.

FAQs

What should I do if a role instance fails to start?

Ensure that IAM user synchronization is complete on the management console, view the role instance logs to locate the cause of the failure, and check whether cluster resources (such as memory and disk space) are sufficient.

What should I do if a role instance becomes abnormal after configuration import?

Ensure that the imported configuration parameter file matches the current role instance version. If the configurations are incompatible, the instance may become abnormal. You are advised to export the current configurations, modify them, and import them again.

Helpful Links

Parent Topic: Managing MRS Cluster Components