A lot of IT managers get confused between what a Oracle RAC does and what Dataguard does.
Oracle RAC provides us with a cluster of Oracle instances for the same database/datastore. This enables massive scalability and availability. But it does not provide protection against failure of the database or corruption of the data. e.g. natural disaster that resulted in data-loss or data-corruption.
Oracle dataguard enables creation of a standby database at a DR site and thus provides data protection.