Starting with Oracle Grid Infrastructure 12c Release 2 (12.2), Oracle Grid Infrastructure cluster configurations are Oracle Flex Clusters deployments.
Oracle Grid Infrastructure installed in an Oracle Flex Cluster configuration is a scalable, dynamic, robust network of nodes. Oracle Flex Clusters provide a platform for Oracle Real Application Clusters databases with large numbers of nodes, to support massive parallel query operations. Oracle Flex Clusters also provide a platform for other service deployments that require coordination and automation for high availability.
All nodes in an Oracle Flex Cluster belong to a single Oracle Grid Infrastructure cluster. This architecture centralizes policy decisions for deployment of resources based on application needs, to account for various service levels, loads, failure responses, and recovery. Nodes in Oracle Flex Clusters are tightly connected, and have direct access to shared storage