Definition of irrigation. 1  1 : the therapeutic flushing of a body part with a stream of liquid. 2  2 : the watering of land by artificial means to foster plant growth.
Answer: To start with, Oracle Real Application Clusters (RAC) are a database system involving a configuration of multiple hosts or servers joined together with clustering software and accessing the shared disk storage structures.
It allows multiple nodes in a clustered system to mount and open a single database that resides on shared disk storage. Should a single system (node) fail, the database service will still be available on the remaining nodes. A non-RAC database is only available on a single system.