The log_archive_duplex_dest parameter allows you to define not one but two archived redo log storage locations. You can define it as a can or must succeed operation by setting the log_archive_min_succeed_dest parameter. This second parameter, if set to 1, does not require that the archived redo log copy to the duplex destination be complete; otherwise, if the parameter is set to a 2, both copies must be successful. If the parameter is set to 2, the database halts until the reason that the archive log cannot be copied is corrected.
Oracle RMAN – Duplexing Archive Logs
