ORA-01102: cannot mount database in EXCLUSIVE mode

SQL> startup ORACLE instance started.   Total System Global Area  835104768 bytes Fixed Size                  2232960 bytes Variable Size             285216128 bytes Database Buffers          541065216 bytes Redo Buffers                6590464 bytes ORA-01102: cannot mount database in EXCLUSIVE mode

Database alert log might show following error.

Wed Sep 04 05:35:30 2013 ALTER DATABASE   MOUNT sculkget: failed to lock /oranfs1/RHAP1/oracle/product/11.2/dbs/lkBRTEST1 exclusive sculkget: lock held by PID: 64 ORA-09968: unable to lock file Linux-x86_64 Error: 11: Resource temporarily unavailable

You might have already ensured that no other instances of this Oracle database is running on this server.

[oracle@RHAP1 ~]$ ps -ef | grep pmon grid     26377     1  0 Sep03 ?        00:00:00 asm_pmon_+ASM oracle   28239 26946  0 06:04 pts/0    00:00:00 grep pmon [oracle@RHAP1 ~]$

Solution

Check for the file pointed by alert log. In my case it was $ORACLE_HOME/dbs/lkBRTEST1 i.e lk. Delete this file and starup the instance.

[oracle@RHAP1 ~]$ cd /oranfs1/RHAP1/oracle/product/11.2/dbs [oracle@RHAP1 dbs]$ ls -ltr lkBRTEST1 -rw-r----- 1 oracle oinstall 24 Aug 26 07:07 lkBRTEST1 [oracle@RHAP1 dbs]$ rm -rf lkBRTEST1

SQL> startup ORACLE instance started.   Total System Global Area  835104768 bytes Fixed Size                  2232960 bytes Variable Size             285216128 bytes Database Buffers          541065216 bytes Redo Buffers                6590464 bytes Database mounted. Database opened.

In some cases sgadef.dbf file under $ORACLE_HOME/dbs can also cause the issue. You can delete this file as well and try to startup the instance.

This issue is more likely to happen when ORACLE_HOME & database files resides on NFS. NFS should be configured properly to release any locks after a server or database crash.