A query hint is a clause you put into the query to make the planner execute the query in a certain way. Planner hint might not be the right term, Oracle has too

A query hint is a clause you put into the query to make the planner execute the query in a certain way. Planner hint might not be the right term, Oracle has tools to show you different execution plans and to force a plan without touching the query on the application side. I'm not sure why shared storage would be a problem, the world runs on SANs and making them redundant is pretty much a solved problem. For running a RAC cluster you are required to have at least two network paths for each cluster node. Furthermore cluster communication is separated from storage communication.