ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u01/app/oracle/oradata/orcl/control01.ctl'
ORA-27086: unable to lock file - already in use
思路：
1、看一下"lk" and "sgadef.dbf"这两个文件是不是存在着，如果存在将其删掉；
2、看是不是有后台进程存在；
3、看一下oracle的共享内存段及信号集(semaphores)是不是还存在着；
实际操作：
[oracle@linux ~]$ cd $ORACLE_HOME/dbs
[oracle@linux dbs]$ ls
hc_SID.dat initdw.ora init.ora lkSID orapwSID spfileSID.ora
[oracle@linux dbs]$ rm lkSID
[oracle@linux dbs]$ ls
hc_SID.dat initdw.ora init.ora orapwSID spfileSID.ora
[oracle@linux dbs]$ ps -ef|grep ora_|grep SID
oracle 4981 1 0 09:00 ? 00:00:00 ora_pmon_SID
oracle 4983 1 0 09:00 ? 00:00:00 ora_psp0_SID
oracle 4985 1 0 09:00 ? 00:00:00 ora_mman_SID
oracle 4987 1 0 09:00 ? 00:00:00 ora_dbw0_SID
oracle 4989 1 0 09:00 ? 00:00:00 ora_lgwr_SID
oracle 4991 1 0 09:00 ? 00:00:01 ora_ckpt_SID
oracle 4993 1 0 09:00 ? 00:00:01 ora_smon_SID
oracle 4995 1 0 09:00 ? 00:00:00 ora_reco_SID
oracle 4997 1 0 09:00 ? 00:00:00 ora_cjq0_SID
oracle 4999 1 0 09:00 ? 00:00:07 ora_mmon_SID
oracle 5001 1 0 09:00 ? 00:00:00 ora_mmnl_SID
oracle 5003 1 0 09:00 ? 00:00:00 ora_d000_SID
oracle 5005 1 0 09:00 ? 00:00:00 ora_s000_SID
oracle 5023 1 0 09:00 ? 00:00:00 ora_qmnc_SID
oracle 5133 1 0 09:00 ? 00:00:00 ora_q000_SID
oracle 5139 1 0 09:00 ? 00:00:00 ora_q001_SID
oracle 31755 1 1 13:21 ? 00:00:00 ora_j000_SID
[oracle@linux dbs]$ ps -ef|grep ora_|grep SID|grep pmon
oracle 4981 1 0 09:00 ? 00:00:00 ora_pmon_SID
[oracle@linux dbs]$ kill -9 4981
[oracle@linux dbs]$ ps -ef|grep ora_|grep SID|grep pmon
[oracle@linux dbs]$ ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
重新startup数据库，问题解决。
