• MapReduce Service

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  1. Help Center
  2. MapReduce Service
  3. User Guide
  4. Cluster Operation Guide
  5. Managing Active Clusters
  6. Expanding a Cluster

Expanding a Cluster

The storage and computing capabilities of MRS can be improved by simply adding Core nodes or Task nodes instead of modifying system architecture, reducing O&M costs. Core nodes can process and store data. You can add Core nodes to increase the number of nodes that process the peak load. Task nodes are used for computing and do not store persistent data.

Background

An MRS cluster supports a maximum of 502 nodes. There are two Master nodes by default. The minimum of 3 Core nodes. A maximum of 500 Core nodes and Task nodes are supported by default. If more than 500 Core nodes and Task nodes are required, contact technical support engineers or invoke a background interface to modify the database.

Core nodes and Task nodes can be added but Master nodes cannot. The maximum number of nodes that can be added equals to 500 minus the number of existing Core nodes or Task nodes. For example, if the number of existing Core nodes is 3, a maximum of 497 nodes can be added. If a cluster fails to be expanded, you can perform capacity expansion for the cluster again.

If no node is added during cluster creation, you can specify the number of nodes to be added during capacity expansion. However, you cannot specify the nodes to be added.

Cluster capacity expansion operations vary according to the cluster version you select.

Procedure

If the cluster version is MRS 1.6.0 or later, perform the following operations:

  1. Log in to the MRS management console.
  2. Click in the upper-left corner on the management console and select Region and Project.
  3. Choose Clusters > Active Clusters, select a running cluster, and click its name to switch to the cluster information page.
  4. Click Resize Cluster and go to the Resize Cluster page.

    The expansion operation can only be performed on the running clusters.

  5. Set Node Type to Core Node or Task Node, configure the Nodes After Resize parameter, and click OK.

    NOTE:
    • If there is no Task Node in the Node Type drop-down list, follow instructions in Related Operation to add the Task node type.
    • If you enable Run Bootstrap Action, the bootstrap action script you add during cluster creation will be executed on all added nodes. Only MRS 1.7.1 or later supports bootstrap actions.

  6. In the Resize Cluster window, click OK.
  7. In the Expand Node dialog box, click OK.

    Cluster expansion is explained as follows:
    • During expansion: The cluster status is Expanding. The submitted jobs will be executed and you can submit new jobs. You are not allowed to continue to expand, restart, modify, or terminate the cluster.
    • Successful expansion: The cluster status is Running. The resources used in the old and new nodes are charged.
    • Failed expansion: The cluster status is Running. You are allowed to execute jobs and expand the cluster again.

    After the cluster expansion is successful, you can view node information on the cluster information page.

If the cluster version is MRS 1.3.0, or MRS 1.5.0, perform the following operations:

  1. Log in to the MRS management console.
  2. Click in the upper-left corner on the management console and select Region and Project.
  3. Choose Clusters > Active Clusters, select a running cluster, and click its name to switch to the cluster information page.
  4. Click Add Node.

    Only the capacity of running clusters can be expanded and only Core nodes can be added.

  5. Set Number of Nodes and click OK.
  6. In the Information dialog box, click OK.

    Cluster expansion is explained as follows:
    • During expansion: The cluster status is Expanding. The submitted jobs will be executed and you can submit new jobs. You are not allowed to continue to expand, restart, modify, or terminate the cluster.
    • Successful expansion: The cluster status is Running. The resources used in the old and new nodes are charged.
    • Failed expansion: The cluster status is Running. You are allowed to execute jobs and expand the cluster again.

    After the cluster capacity expansion is successful, you can view node information on the cluster information page.

Related Operation

Perform the following operations to add Task nodes:
  1. On the cluster information page, click  behind Task to add Task Node.
  2. On the Add Task Node page, configure Instance Specifications and Nodes. In addition, if Add Data Disk is enabled, configure the storage type, size, and number of data disks and click OK.
  3. In the Information dialog box, click OK.