Oracle 12C GDS

Oracle Global Data Services (GDS) implements the Oracle Database service model across a set of replicated databases known as a Global Data Services configuration.

A Global Data Services configuration looks like a virtual multi-instance database to database clients. It provides client access through global services, which are functionally similar to the local database services provided by single-instance or Oracle Real Application Clusters (Oracle RAC) databases. Local and global services both provide load balancing, high availability, and resource management. The essential difference between global services and local services is that global services span the instances of multiple databases, whereas local services span the instances of a single database.