Database services (services) are logical abstractions for managing workloads in Oracle Database. Each service represents a workload with common attributes, service-level thresholds, and priorities.
In Real Application Clusters (RAC), a service can span one or more
instances and facilitate real workload balancing based on real
transaction performance. RAC also enables you to manage a number of service features with
Enterprise Manager, the DBCA, and the Server Control utility (SRVCTL).