:original_name: mrs_01_1736.html

.. _mrs_01_1736:

Managing a HetuEngine Compute Instance
======================================

Scenario
--------

On the HetuEngine web UI, you can start, stop, delete, and roll-restart a single compute instance or compute instances in batches.

.. important::

   -  Restarting HetuEngine

      During the restart or rolling restart of HetuEngine, do not create, start, stop, or delete HetuEngine compute instances on HSConsole.

   -  Restarting HetuEngine compute instances

      -  During the restart or rolling restart of HetuEngine compute instances, do not perform any change operations on the data sources on the HetuEngine and HetuEngine web UI, including restarting HetuEngine and changing its configurations.

      -  If a compute instance has only one coordinator or worker, do not roll-restart the instance.

      -  If the number of workers is greater than 10, the rolling restart may take more than 200 minutes. During this period, do not perform other O&M operations.

      -  During the rolling restart of compute instances, HetuEngine releases Yarn resources and applies for them again. Ensure that the CPU and memory of Yarn are sufficient for starting 20% workers and Yarn resources are not preempted by other jobs. Otherwise, the rolling restart will fail.

         Viewing Yarn resources: Log in to FusionInsight Manager and choose **Tenant Resources**. On the navigation pane on the left, choose **Tenant Resources Management** to view the available queue resources of Yarn in the **Resource Quota** area.

         Viewing the CPU and memory of a worker container: Log in to FusionInsight Manager as a user who can access the HetuEngine WebUI and choose **Cluster** > **Services** > **HetuEngine**. In the **Basic Information** area, click the link next to **HSConsole WebUI** to go to the HSConsole page. Click **Operation** in the row where the target instance is located and click **Configure**.

      -  During the rolling restart, ensure that Application Manager of coordinators or workers in the Yarn queue runs stably.

      Troubleshooting

      -  If Application Manager of coordinators or workers in the Yarn queues is restarted during the rolling restart, the compute instances may be abnormal. In this case, you need to stop the compute instances and then start the compute instance for recovery.
      -  Compute instances are in the subhealthy state if they fail to be roll-restarted, which may lead to inconsistent configuration or number of coordinators or workers. In this case, the subhealth state of the instances will not be automatically restored. You need to manually check the instance status or restore the instance to healthy by performing the rolling restart again or stopping the compute instances.

Prerequisites
-------------

You have created an HetuEngine administrator for accessing the HetuEngine web UI. For details, see :ref:`Creating a HetuEngine User <mrs_01_1714>`.

.. note::

   -  Users in the **hetuadmin** user group are HetuEngine administrators. Administrators have the permission to start, stop, and delete instances, and common users have only the permission to query instances.
   -  To modify the configuration of the current compute instance, you need to delete the instance on the HSConsole page.

Procedure
---------

#. Log in to FusionInsight Manager as an administrator who can access the HetuEngine web UI and choose **Cluster** > **Services** > **HetuEngine**. The **HetuEngine** service page is displayed.
#. In the **Basic Information** area on the **Dashboard** page, click the link next to **HSConsole WebUI**. The HSConsole page is displayed.
#. In the **Operation** column of the instance, you can perform the following operations on a single job:

   -  To start an instance, click **Start**.
   -  To stop an instance, click **Stop**.
   -  To delete an instance that is no longer used, click **Delete**. The configuration information of the instance is also deleted.
   -  To roll-restart an instance, click **Rolling Restart**.

#. In the upper part of the instance list, you can perform the following operations on jobs:

   -  To start instances in batches, select the target instances in the instance list and click **Start**.
   -  To stop instances in batches, select the target instances in the instance list and click **Stop**.
   -  To delete instances in batches, select the target instances in the instance list and click **Delete**.
   -  To roll-restart instances in batches, select the target instances in the instance list and click **Rolling Restart**.
