This section has all you need to know pertaining to administering the cluster in Redis Enterprise Software.
When you install RS 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 The clocks on all nodes must always be synchronized. If the clock in the node you are trying to join to the cluster is not synchronized with the nodes already in the cluster, the action fails and an error message is shown indicating that you must synchronize the clocks first.
Prepare node for maintenance, and restore it to previous state
A Redis Enterprise Software (RS) cluster typically consists of several nodes. For production deployments, Redis Labs recommends 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 as described in the previous section and then set up the cluster as described below.
There are various reasons why you may want to remove a node in Redis Enterprise Software (RS): You no longer need the extra capacity, meaning you want 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.
If a node in your cluster is faulty, its status appears as **Down **in the Status column of the Nodes page, and in the Cluster > Configuration page. To replace a faulty node: Acquire a new node that is identical to the old node, install and configure Redis Enterprise Software on it per the install instructions. Note: If you are using Redis on Flash, you must make sure the required flash storage is set up on this new node.
Cluster License Keys The cluster key (or license) enables features and capacity within Redis Enterprise Software. You can add or update a cluster key at any time in a cluster lifecycle. When the cluster does not have a cluster key, the cluster is in trial mode. Trial Mode Trial mode is limited to thirty days and a total of four shards, including master and slave shards. Any new installation starts its thirty-day clock from the day the cluster setup was done (with the first cluster node provisioned).
Because Redis is an in-memory database, when you stop a machine that hosts a Redis Enterprise Software (RS) node that has databases with persistence enabled, either: Redis can delay the machine shutdown as the databases with persistence enabled try to save the data to disk. The length of the delay depends on the number of databases and the size of the data. The operating system can force the node to stop before all of the data is saved to disk.
Redis Enterprise Software (RS) uses self-signed certificates out-of-the-box to make sure that the product is secure by default. The self-signed certificates are used to establish encryption-in-transit for the following traffic: Management Web UI (CM) - The certificate for connections to the management web UI REST API - The certificate for REST API calls Proxy - The certificate for connections between clients and database endpoints Syncer - The certificate for synchronization between databases for ReplicaOf and CRDB Metrics exporter - The certificate to export metrics to Prometheus These self-signed certificates are generated on the first node of each RS installation and are copied to all other nodes added to the cluster.
On the Cluster > Metrics page you can view detailed real-time graphs of various metrics for the entire cluster, as well as specific nodes. You can choose which resources and metric to display in each of the two detailed graphs at the top of the page, as follows: Below the top two graphs there are two groups of smaller graphs: The first group displays all available resources: the cluster itself, and each of the cluster nodes.
On the Node > Metrics page you can view detailed graphs of various node metrics in real-time. You can choose which metrics are shown in each of the two graphs at the top of the page, as follows: Below the top two graphs there is a group of smaller graphs that displays all available metrics, such as CPU utilization and operations per second. In each of the bottom graphs, clicking the left arrow displays that metric in the top left graph, while clicking the right arrow displays that metric in the top right graph.