When you initialize a database instance, the database system deletes all data (application data and the database catalog) and all log entries from the volumes. The configuration of the database instance (database parameters, volume definitions and so on) is retained, however.
See also:
Database Manager GUI,
Initializing an Existing Database Instance
Restoring After Initializing a Database Instance
Database Manager CLI,
Concepts of the Database System, Restoring the Database Instance