What is Single-Client Access Name(SCAN) in oracle RAC database? What is the advantage of SCAN address in oracle RAC database?
Single Client Access Name (SCAN) is a feature used in Oracle Real Application Clusters
environments that provides a single name for clients to access any Oracle Database running
in a cluster. You can think of SCAN as a cluster alias for databases in the cluster. The benefit
is that the client’s connect information does not need to change if you add or remove nodes or
databases in the cluster.
The SCAN provides a stable, highly available name for clients to use, independent of the nodes that make up the cluster. If you use GNS, and you have DHCP support, then the GNS will assign addresses
dynamically to the SCAN. And If you do not use GNS, the SCAN should be defined in the DNS to resolve to the three addresses assigned to that name.