Standby Online Redo Log

July 23, 2009
Oracle, Standby, Redo Log
  The synchronous and asynchronous redo transport modes require that a redo transport destination have a standby redo log. A standby redo log is used to store redo received from another Oracle database. Standby redo logs are structurally identical to redo logs, and are created and managed using the same SQL statements used to create and manage redo logs.
  Redo received from another Oracle database via redo transport is written to the current standby redo log group by a RFS background process. When a log switch occurs on the redo source database, incoming redo is then written to the next standby redo log group, and the previously used standby redo log group is archived by an ARCn background process.