RAC One Node
RAC One Node, widely acknowledged as “the always-on single–server database,” was first introduced with Oracle 11gR2 (18.104.22.168) Enterprise Edition to render High Availability solutions for single-instance databases. RAC One Node is a single-instance RAC database that runs on a single node in a cluster at any given point. The core objective of RAC One Node features is to minimize the impact of single-instance database availability during planned and unplanned server outages through its exceptional online database migration capabilities. In addition, with the online database conversion capabilities, a RAC One Node database can easily be scaled out to a fully functional traditional RAC database.