ORA-01102 Solution

Ora-01102 error occurred when starting after Oracle database is installed.
Oracle@r05a11016.yh.com:/home/oracle> sqlplus "/as sysdba"
SQL * Plus: Release 11.2.0.2.0 Production on Fri Apr 15 16:17:39 2011
Copyright (c) 1982,201 0, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 1.7103E + 10 bytes
Fixed Size 2243608 bytes
Variable Size 8455717864 bytes
Database Buffers 8623489024 bytes
Redo Buffers 21712896 bytes
ORA-01102: cannot mount database in EXCLUSIVE mode
I checked ml and learned the cause of ORA-1102 error:
1. in ORACLE_HOME/dbs/, the "sgadef <sid>. dbf" or lk <db_name> file exists. These two files are used to lock the memory.
2 oracle processes such as pmon, smon, lgwr and dbwr are not properly shut down.
3. After the database is closed, the shared memory or semaphore is still occupied.
Lk <SID> indicates that the DATABASE is already in the MOUNT state and you do not need to MOUNT it again. when the DATABASE is unmounted, it is automatically deleted. If the DATABASE is not mounted, this problem still exists. You only need to manually delete it.
Specific steps to solve the ORA-01102 problem:
--------------------
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0> cd dbs
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0/dbs> ll lk *
-Rw-r ----- 1 oracle oinstall 24 Apr 15:43 lkORCL
Use fuser-u lkORCL to view the processes and users using the lkORCL file. -U provides the login name for the local process in parentheses after the process number.
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0/dbs>/sbin/fuser-u lkORCL
LkORCL: 21007 (oracle) 21009 (oracle) 21015 (oracle) 21019 (oracle) 21023 (oracle) 21025 (oracle) 21027 (oracle) 21029 (oracle) 21031 (oracle) 21033 (oracle) 21035 (oracle) 21037 (oracle) 21039 (oracle) 21041 (oracle)
Use fuser-k lkORCL to kill the processes that are accessing lkORCL-k to kill the processes that are accessing these files.
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0/dbs>/sbin/fuser-k lkORCL
LkORCL: 21007 21009 21015 21019 21023 21025 21027 21029 21031 21033 21035 21037 21039 21041
Confirmation: all processes are terminated.
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0/dbs>/sbin/fuser-u lkORCL
Restart:
Oracle@r05a11016.yh.com:/apsarapangu/disk1/opt/oracle/products/11.2.0/dbs> sqlplus "/as sysdba"
SQL * Plus: Release 11.2.0.2.0 Production on Fri Apr 15 16:30:16 2011
Copyright (c) 1982,201 0, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 1.7103E + 10 bytes
Fixed Size 2243608 bytes
Variable Size 8455717864 bytes
Database Buffers 8623489024 bytes
Redo Buffers 21712896 bytes
Database mounted.
Database opened.

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