报错信息：
SQL> startup
ORACLE instance started.

Total System Global Area 849530880 bytes
Fixed Size 1339824 bytes
Variable Size 515903056 bytes
Database Buffers 327155712 bytes
Redo Buffers 5132288 bytes
ORA-00205: error in identifying control file, check alert log for more info

查看警报日志文件：
ALTER DATABASE MOUNT
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u01/app/oracle/flash_recovery_area/orcl/control02.ctl'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u01/app/oracle/oradata/orcl/control01.ctl'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
ORA-205 signalled during: ALTER DATABASE MOUNT...
错误显示丢失了control01.ctl 和control02.ctl

查看参数control_files的值：
SQL> show parameter control_files
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
control_files string /u01/app/oracle/oradata/orcl/c
ontrol01.ctl, /u01/app/oracle/
flash_recovery_area/orcl/contr
ol02.ctl

由此可知数据库中的所有控制文件全部丢失。
而在rman中是没有开启configure controlfile autobackup on;的。于是我们只能通过重建控制文件来恢复数据库了。
由于数据库缺失控制文件无法mount，所以不能使用alter database backup controlfile to trace获取控制文件脚本。
但是我们可以找到oracle的建库脚本，依据实际情况自己创建一个重建控制文件的脚本。
脚本createcontrol.sql内容如下：
STARTUP NOMOUNT
CREATE CONTROLFILE REUSE SET DATABASE "ORCL"
MAXINSTANCES 8
MAXLOGHISTORY 1
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
DATAFILE
'/u01/app/oracle/oradata/orcl/system01.dbf',
'/u01/app/oracle/oradata/orcl/sysaux01.dbf',
'/u01/app/oracle/oradata/orcl/undotbs01.dbf',
'/u01/app/oracle/oradata/orcl/users01.dbf',
'/u01/app/oracle/oradata/orcl/test01.dbf'
LOGFILE GROUP 1 ('/u01/app/oracle/oradata/orcl/redo01.log') SIZE 51200K,
GROUP 2 ('/u01/app/oracle/oradata/orcl/redo02.log') SIZE 51200K,
GROUP 3 ('/u01/app/oracle/oradata/orcl/redo03.log') SIZE 51200K RESETLOGS;

运行脚本：
SQL> @createcontrol.sql
ORACLE instance started.

Total System Global Area 849530880 bytes
Fixed Size 1339824 bytes
Variable Size 515903056 bytes
Database Buffers 327155712 bytes
Redo Buffers 5132288 bytes

Control file created.

打开数据库：

SQL> alter database open resetlogs;

Database altered.

没有自动备份的情况下控制文件全部丢失的恢复