Testing does not end when the data warehouse goes live. Data warehouses are evolving environments, and will typically start out smaller than their ultimate size. The backup and recovery tests need to be carried out on a regular basis. It is suggested that the full test suite should be run twice a year, or at the very least annually. As the system itself is live, and many of the tests will be destructive, people are often wary of running these tests. The way to deal with this is to have a testing and development environment that matches the live environment.