问题现象：
QL> startup ORACLE instance started. Total System Global Area 1854021632 bytes Fixed Size 2242584 bytes Variable Size 1136658408 bytes Database Buffers 708837376 bytes Redo Buffers 6283264 bytes ORA-00205: error in identifying control file, check alert log for more info
查看alert日志内容如下：
ALTER DATABASE MOUNT ORA-00210: cannot open the specified control file ORA-00202: control file: '/opt/oracle/oradata/mrad/sys03/control03.ctl' ORA-27086: unable to lock file - already in use SVR4 Error: 11: Resource temporarily unavailable Additional information: 8 Additional information: 1084 ORA-00210: cannot open the specified control file ORA-00202: control file: '/opt/oracle/oradata/mrad/sys02/control02.ctl' ORA-27086: unable to lock file - already in use SVR4 Error: 11: Resource temporarily unavailable Additional information: 8 Additional information: 1084 ORA-00210: cannot open the specified control file ORA-00202: control file: '/opt/oracle/oradata/mrad/sys01/control01.ctl' ORA-27086: unable to lock file - already in use SVR4 Error: 11: Resource temporarily unavailable Additional information: 8 Additional information: 1084
解决问题思路
日志提示oracle控制文件已经被占用了，数据库却没有启动成功。具体的要想办法关闭oracle所有进程，重启数据库服务器是最佳的选择，
注意：重启数据库服务器要自己手动启动oracle数据库才能解决问题，如果oracle数据库设置开机自启动请先关闭自启，然后再重启数据库服务器！！！