"We have RAC, so we're covered for DR." It's one of the most expensive sentences in Oracle operations,
and I've watched variations of it play out more than once. Real Application Clusters (RAC) and Data
Guard both live under the "high availability" umbrella, so it's easy to assume they're interchangeable
— or that having one means you don't need the other. They are not interchangeable. They solve
different failures, and the cost of confusing them is usually discovered at the worst possible time.
