How to Add Standby Nodes to MySQL Database Clusters

MySQL is an open source, object-relational database built with speed and reliability in mind. Its large and active developer community has created many third-party applications, tools, and libraries that expand MySQL’s functionality.

In a database cluster, standby nodes maintain a copy of the primary node. If the primary node fails, a standby node is automatically promoted to replace it. MySQL clusters can have up to two standby nodes.

Note

Standby nodes differ from read-only nodes, which provide geographically distinct horizontal read scaling.

You can add standby nodes during cluster creation in the cluster configuration section of the create page.

You can also add standby nodes to an existing database cluster. From the Databases page, click the name of the cluster to go to its Overview page, then click the Settings tab.

On the Settings page, in the Cluster configuration section, click Edit. Open the Standby Nodes dropdown and choose the number of standby nodes.

Note

Due to the memory requirements of replication, standby nodes are only supported for plans with 2GB of RAM or more.

When you’re done, click Save to immediately provision the standby nodes. The time to complete varies depending on the size of the primary node and its data, but we recommend allowing at least 5 minutes.