Documentation - Redise Pack

A guide to Redise Pack installation, operation and administration

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Removing a Node

There are various reasons why you may want to remove a node:

  • You no longer need the extra capacity, meaning you wish to permanently remove the node.
  • You would like to replace a faulty node with a healthy node.
  • You would like to replace a healthy node with a different node.

The following section explains how each of these actions can be achieved, as well as their impact and considerations.

Make sure to read through these explanations thoroughly before taking any action.

Permanently removing a node

Permanently removing a node means you are decreasing cluster capacity. Before trying to remove a node, ensure that the cluster has enough capacity for all resources without that node, otherwise you will not be able to remove the node.

If there is not enough capacity in the cluster to facilitate removing the node, you can either delete databases or add another node instead of the one you would like to remove.

During the removal process, the cluster migrates all resources from the node being removed to other nodes in the cluster. In order to ensure database connectivity, and database high availability (when replication is enabled), the cluster first creates replacement shards or endpoints on one of the other nodes in the cluster, initiates failover as needed, and only then removes the node.

If a cluster has only two nodes (which is not recommended for production deployments) and some databases have replication enabled, you will not be able to remove a node.

Replacing a faulty node

If the cluster has a faulty node that you would like to replace, you only need to add a new node to the cluster. The cluster recognizes the existence of a faulty node and automatically replaces the faulty node with the new node.

For guidelines, refer to Replacing a faulty node.

Replacing a healthy node

If you would like to replace a healthy node with a different node, you must first add the new node to the cluster, migrate all the resources from the node you would like to remove, and only then remove the node.

For further guidance, refer to adding a new node to a cluster.

You can migrate resources by using the rladmin command-line interface (CLI). For guidelines, refer to rladmin command line interface (CLI).

Note: The DNS records must be updated each time a node is added or replaced. For additional details, refer to DNS.

To remove a node:

  1. Click Remove at the top of the Node page for the node to be removed.
  2. Approve the action.
  3. RP examines the node and the cluster and takes the actions required to remove the node.
  4. At any point, you can click the Abort button to stop the process. When aborted, the current internal action is completed, and then the process stops.
  5. Once the process finishes, the node will no longer be displayed in the UI.

You can choose to receive email alerts related to this process, as described in Managing cluster alerts.

Note: Once you remove a node, if you need to add it back to a cluster, you must first uninstall and reinstall the software.