問題現象：
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日志內容如下：
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
解決問題思路
日志提示oracle控制文件已經被占用了，數據庫卻沒有啟動成功。具體的要想辦法關閉oracle所有進程，重啟數據庫服務器是最佳的選擇，
注意：重啟數據庫服務器要自己手動啟動oracle數據庫才能解決問題，如果oracle數據庫設置開機自啟動請先關閉自啟，然后再重啟數據庫服務器！！！