Manage clusters on Docs

Set up a new cluster

Mon, 01 Jan 0001 00:00:00 +0000

A Redis Enterprise Software cluster typically consists of several nodes. For production deployments, we recommend an uneven number of nodes, with a minimum of three.

Note:

In a cluster that consists of only one node, some features and capabilities are not enabled, such as database replication that provides high availability.

To set up a new cluster, you must first install the Redis Enterprise Software package and then set up the cluster as described below. After the cluster is created you can add multiple nodes to the cluster.

Add a node

Mon, 01 Jan 0001 00:00:00 +0000

When you install Redis Enterprise Software on the first node of a cluster, you create the new cluster. After you install the first node, you can add more nodes to the cluster.

Prerequisites

Before you add a node to the cluster:

Maintenance mode for cluster nodes

Mon, 01 Jan 0001 00:00:00 +0000

Use maintenance mode to prevent data loss during hardware patching or operating system maintenance on Redis Enterprise servers. When maintenance mode is on, all shards move off of the node under maintenance and migrate to another available node.

Activate maintenance mode

When you activate maintenance mode, Redis Enterprise does the following:

Change node roles

Mon, 01 Jan 0001 00:00:00 +0000

A Redis Software cluster contains a primary node, which coordinates cluster-wide management operations, and multiple secondary nodes. Nodes with either role can host database shards.

Demote primary node

Cluster Manager UI rladmin

To demote the primary node to a secondary node using the Cluster Manager UI:

Recover a failed cluster

Mon, 01 Jan 0001 00:00:00 +0000

When a Redis Enterprise Software cluster fails, you must use the cluster configuration file and database data to recover the cluster.

Note:

For cluster recovery in a Kubernetes deployment, see Recover a Redis Enterprise cluster on Kubernetes.

Cluster failure can be caused by:

A hardware or software failure that causes the cluster to be unresponsive to client requests or administrative actions.
More than half of the cluster nodes lose connection with the cluster, resulting in quorum loss.

To recover a cluster and re-create it as it was before the failure, you must restore the cluster configuration ccs-redis.rdb to the cluster nodes. To recover databases in the new cluster, you must restore the databases from persistence files such as backup files, append-only files (AOF), or RDB snapshots. These files are stored in the persistent storage location.

Remove a node

Mon, 01 Jan 0001 00:00:00 +0000

You might want to remove a node from a Redis Enterprise cluster for one of the following reasons:

To permanently remove a node if you no longer need the extra capacity.
To replace a faulty node with a healthy node.
To replace a healthy node with a different node.

You can configure email alerts from the cluster to notify you of cluster changes, including when a node is removed.

Warning:

Read through these explanations thoroughly before taking any action.

Permanently remove a node

Permanently removing a node means you are decreasing cluster capacity. Before trying to remove a node, make sure that the cluster has enough capacity for all resources without that node, otherwise you cannot remove the node.

Replace a cluster node

Mon, 01 Jan 0001 00:00:00 +0000

A failed node will appear as Down ( ) in the Nodes list.

To replace a failed node:

Prepare a new node identical to the old one.
Install and configure Redis Enterprise Software on the node. See Install and setup for more information.

Note:
If you are using Redis Flex or Auto Tiering, make sure the required flash storage is set up on this new node.
Add the node to the cluster. Make sure the new node has as much available memory as the faulty node.