Figure 21.1 InnoDB Cluster overview Being built on MySQL Group Replication, provides features such as automatic membership management, fault tolerance, automatic failover, and so on. An InnoDB Cluster usually runs in a single-primary mode, with one primary instance (read-write) and multiple secondary instances (read-only). Advanced users can also take advantage of a multi-primary mode, where all instances are primaries. You can even change the topology of the cluster while InnoDB Cluster is online, to ensure the highest possible availability. 3916