Managing an Application Cluster

The clustering system is designed to make it easy to add and remove cluster nodes. By virtue of connecting to an application database that other cluster nodes are using, a node will automatically discover and join the cluster on startup. You can remove a node using the Admin Console.

Be sure to see the clustering overview for a high-level view of how clustering works.

Enabling and Disabling a Cluster

You can enable or disable clustering in the Admin Console. See Configuring a Cluster Node for more information.

Adding a Cluster Node

When you add a new node to the cluster, you must restart every node in the cluster to ensure that the new node is seen by the others. To avoid competition for senior node status, make sure you wait a minute or more between restarting each node and ensure each one is properly initialized.

You might also be interested in Setting Up a Cluster, which describes the process for installing or upgrading the application on an entire cluster.

Fastpath: Admin Console: System > Settings > Cluster
  1. Install the application on the new node as described in Installing the Linux Package.
  2. Finish setting up the new node, restart it, and let it get up and running.

    By default, the node will scan for the TCP endpoint and register itself in the database. You can also specify a particular endpoint in the Admin Console as described in Configuring a Cluster Node.

  3. Restart all nodes in the cluster so that the other nodes can become aware of the new node.

Removing a Cluster Node

When you want to be sure that a node's registration is removed from the database, you can remove a node from a cluster by using the Admin Console.

Fastpath: Admin Console: System > Settings > Cluster
  1. Ensure that the node you want to remove is shut down.
  2. In the Admin Console for any of the nodes in the cluster, on the Cluster page, locate the address of the node you want to remove.
  3. Next to the node's address, select the Remove check box.
  4. Click Save to save settings and remove the address from the database.

    Settings will be automatically replicated across the cluster.