Add nodes to a cluster setup

As an RPA platform administrator, you can add nodes to a cluster for better performance and better load distribution.

Prerequisites

Ensure the following:

  • Verify whether the prerequisites for on-premises installation are met.

    Automation 360 On-Premises prerequisites

  • Verify that all the primary nodes and databases have backups.
  • You must have the IP addresses of all the cluster members for the Control Room server network interfaces used for Elasticsearch communications.
    Note: The Control Room servers can have multiple network interfaces. The server IP addresses must be statically assigned and cannot use the Dynamic Host Configuration Protocol (DHCP).
  • If any external load balancers are used in the environment, update them with IP addresses from the new server nodes.
  • Ensure that you have administrator or root privileges on the Control Room servers. You must be familiar with installing Control Room in custom mode and also with the related configuration settings.

Adding nodes to a cluster helps you to update the configuration of the nodes in a cluster. You can add nodes to a Control Room cluster setup, change the IP addresses of nodes in the cluster, and monitor the health of the underlying cluster services.

Note: The minimal number of nodes supported within a Control Room cluster is three. The nodes in a cluster synchronize with each other over a local network. All the nodes in a cluster connect to the same database.

Perform the following steps to add three nodes (N4, N5, and N6) to a cluster that has three nodes (N1, N2, and N3).

Procedure

  1. On node N4, log in to the operating system as an administrator and run the Control Room installer.
  2. Proceed through the installer to the cluster configuration.
    1. Select Enable Cluster Setup.
    2. In the Cluster IP addresses box, enter the IP addresses of all the nodes that you need to configure in the cluster.
      172.31.30.120, 172.31.21.216, 172.31.17.110, 172.31.20.242, 172.31.17.149, 172.31.18.37
    3. Select or add your Local IP address.
    Note: The IP addresses must be entered in the same sequence on every node.
  3. Restart the nodes, one at a time.
    After you restart the nodes, each node will have six IP addresses.
  4. Complete the remaining steps to install Control Room.
    Installing Control Room On-Premises
  5. Repeat the steps 1 through 4 for nodes N5 and N6.
  6. Ensure that all the Control Room services have started for all the nodes.
  7. To verify the health of the cluster, use the Elasticsearch API through a browser or API tool.
    1. From a browser, navigate to the IP address of any node in the cluster by using the Elasticsearch port 47599 and use the _cat/nodes API.
      https://172.31.30.120:47599/_cat/nodes
      The primary node is indicated by an asterisk character (*).
    2. Verify that the IP address of the primary node is the same as the one mentioned in the elasticsearch.yml file for all the nodes.
    3. From a browser, navigate to the IP address of any node in the cluster by using the Elasticsearch port 47599 and use the _cat/health?pretty API.
      https://172.31.30.120:47599/_cat/health?pretty
    The replication status turns green when the cluster is fully synchronized.. You must wait until the replication status turns green. The replication time varies depending on the data load in the clusters.