ORA-01102: cannot mount database in EXCLUSIVE mode

When you run startup command then there is a error occured :

ORA-01102: cannot mount database in EXCLUSIVE mode
The possible cause of error are many but I disscuss one of them.

ORA-01102 occurs when you are mounting (opening) a database, typically because another instance is already opened in parallel (exclusive) mode.
SQL> startup;
ORACLE instance started.

Total System Global Area  481259520 bytes
Fixed Size                  1337352 bytes
Variable Size             167774200 bytes
Database Buffers          306184192 bytes
Redo Buffers                5963776 bytes
ORA-01102: cannot mount database in EXCLUSIVE mode
 Solution


SQL> shut abort
ORACLE instance shut down.
SQL> exit      
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

Now kill your process using this command

[oracle@localhost ~]$ ps -ef|grep pmon
oracle    2591 22013  0 21:58 pts/1    00:00:00 grep pmon
oracle    5035     1  0 18:41 ?        00:00:07 asm_pmon_+ASM
oracle   23130     1  0 21:23 ?        00:00:00 ora_pmon_orcl

[oracle@localhost ~]$ kill -9 23130
[oracle@localhost ~]$ kill -9 5035

Now again run...



[oracle@localhost ~]$ sqlplus / as sydba
SQL> startup;


I hope this material help you so much.
If you want to give any suggestion please comment.