Scaling Out a Cluster

Background

The MRS cluster supports a maximum of 500 core and task nodes. If more than 500 core/task nodes are required, contact technical support or call a background interface to modify the database.

Only core and task nodes can be added. The maximum number of core/task nodes to be added is 500 minus the number of core/task nodes in the cluster. For example, the current number of Core nodes is 3, the number of Core nodes to be added must be less than or equal to 497. If the cluster scale-out fails, you can add node to the cluster again.

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

The operations for scaling out a cluster vary depending on the selected version.

Constraints

• When you expand a node group where HBase is installed:

  If automatic DNS registration is not enabled for a node in the cluster, do not start HBase when you expand the node group. Then, update the HBase client configuration by referring to Updating the Client Configuration and start the HBase instances on the node to be expanded.

• After a scale-out, the clients installed on nodes in the cluster do not need to be updated. For details about how to update the client installed on nodes outside the cluster, see Updating the Client Configuration.

Procedure

1. Log in to the MRS console.
2. Choose Clusters > Active Clusters, select a running cluster, and click its name to switch to the cluster details page.
3. Click the Nodes tab. In the Operation column of the node group, click Scale Out. The Scale Out page is displayed.

   The scale-out operation can only be performed on the running clusters.

4. Set Scaled Out Nodes, Enable Component, and Run Bootstrap Action, and click OK
   

   • If the Task node group does not exist in the cluster, configure the Task node by referring to Adding a Task Node.
   • If a bootstrap action is added during cluster creation, the Run Bootstrap Action parameter is valid. If this function is enabled, the bootstrap actions added during cluster creation will be run on all the scaled out nodes.
   • If the New Specifications parameter is available, the specifications that are the same as those of the original nodes have been discontinued. Nodes with new specifications will be added.
   • Before scaling out the cluster, check whether its security group configuration is correct. Ensure that an inbound security group rule contains a rule in which Protocol & Port is set to All, and Source is set to a trusted accessible IP address range.

5. In the Scale Out Node dialog box, click OK.
6. A dialog box is displayed, indicating that the scale-out task is submitted successfully.
   The following parameters explain the cluster scale-out process:

   • Expanding: If a cluster is being expanded, its status is Scaling out. The submitted jobs will be executed and you can submit new jobs. You are not allowed to continue to scale out or delete the cluster. You are advised not to restart the cluster or modify the cluster configuration.
   • Expansion succeeded: If a cluster is expanded successfully, its status is Running.
   • Failed scale-out: The cluster status is Running when the cluster scale-out failed. You can execute jobs and scale out the cluster again.

   After the cluster is scaled out, you can view the node information of the cluster on the Nodes page.

Adding a Task Node

You can scale out an MRS cluster by manually adding task nodes.

To add a task node to a custom cluster, perform the following steps:

1. On the cluster details page, click the Nodes tab and click Add Node Group. The Add Node Group page is displayed.
2. Select Task forNode Type. Retain the default value NM for Deploy Roles. To deploy the NodeManager role, the node type must be Task. Set other parameters as required.

Adding a Node Group

Used to add node groups and applies to customized clusters of MRS 3.x.

1. On the cluster details page, click the Nodes tab and click Add Node Group. The Add Node Group page is displayed.
2. Set the parameters as needed.

   Table 1 Parameters for adding a node group

   Parameter	Description
   Instance Specifications	Select the flavor type of the hosts in the node group.
   Nodes	Set the number of nodes in the node group.
   System Disk	Set the specifications and capacity of the system disk on the new node.
   Data Disk (GB)	Set the specifications, capacity, and number of data disks of the new node.
   Deploy Roles	Deploy the instances of each node in the new node group. The setting can be manually adjusted.

3. Click OK.