Problem
ORA-01102: cannot mount database in EXCLUSIVE mode during database instance startup
sqlplus / as sysdba
QL*Plus: Release 12.2.0.1.0 Production on Tue Apr 30 21:26:57 2019
Copyright (c) 1982, 2016, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 6174015488 bytes
Fixed Size 8634320 bytes
Variable Size 1241514032 bytes
Database Buffers 4915724288 bytes
Redo Buffers 8142848 bytes
ORA-01102: cannot mount database in EXCLUSIVE mode
Solution
Same as
https://sk.solutionmentors.com/2019/04/ora-01012-not-logged-on-startup-failed.html, seems this problem appeared because database was not stopped properly.
Follow great article
http://www.dba-oracle.com/t_ora_01102_cannot_mount_database_in_exclusive_mode.htm
+++++++++++
POSSIBLE SOLUTION:
Verify that the database was shutdown cleanly by doing the following:
1. Verify that there is not a "sgadef<sid>.dbf" file in the directory
"ORACLE_HOME/dbs".
% ls $ORACLE_HOME/dbs/sgadef<sid>.dbf
If this file does exist, remove it.
% rm $ORACLE_HOME/dbs/sgadef<sid>.dbf
2. Verify that there are no background processes owned by "oracle"
% ps -ef | grep ora_ | grep $ORACLE_SID
If background processes exist, remove them by using the Unix
command "kill". For example:
% kill -9 <Process_ID_Number>
3. Verify that no shared memory segments and semaphores that are owned
by "oracle" still exist
% ipcs -b
If there are shared memory segments and semaphores owned by "oracle",
remove the shared memory segments
% ipcrm -m <Shared_Memory_ID_Number>
and remove the semaphores
% ipcrm -s <Semaphore_ID_Number>
NOTE: The example shown above assumes that you only have one
database on this machine. If you have more than one
database, you will need to shutdown all other databases
before proceeding with Step 4.
4. Verify that the "$ORACLE_HOME/dbs/lk<sid>" file does not exist. This is what caused issue in our case. Simple removal of this file did the trick.
5. Startup the instance
Related issues
https://sk.solutionmentors.com/2019/04/ora-01012-not-logged-on-startup-failed.html
https://sk.solutionmentors.com/2019/04/ora-27125-unable-to-create-shared.html
Reference
http://www.dba-oracle.com/t_ora_01102_cannot_mount_database_in_exclusive_mode.htm