Install Oracle Enterprise Manager 12C release 2( on OEL 5/6

This article presents installation of new Oracle Enterprise Manager 12C version on OEL5, OEL6. You need at least 5GB of memory for this installation so check your VirtualBox settings before proceeding.

Read following article to find out how to install OEL5,6 and database 11G Linux. They are required for this installation:

This installation was done on OEL5 but it’s no different on OEL6(extra library must be installed)

1. First step is to deinstall database control from current database as user oracle

emca -deconfig dbcontrol db -repos drop

you will be asked to enter database SID, port, sys and sysman password

[oracle@oel5 ~]$ emca -deconfig dbcontrol db -repos drop

STARTED EMCA at Oct 16, 2012 9:32:02 PM
EM Configuration Assistant, Version Production
Copyright (c) 2003, 2011, Oracle.  All rights reserved.

Enter the following information:
Database SID: ORA11G
Listener port number: 1521
Password for SYS user:  
Password for SYSMAN user:  

WARNING : While repository is dropped the database will 
          be put in quiesce mode.
Do you wish to continue? [yes(Y)/no(N)]: Y
Oct 16, 2012 9:33:34 PM oracle.sysman.emcp.EMConfig perform
INFO: Repository successfully dropped
Enterprise Manager configuration completed successfully
FINISHED EMCA at Oct 16, 2012 9:36:49 P

2.Install extra software as root (only for OEL6)

yum install glibc-devel.i686

3. Make sure the shared memory filesystem is big enough for Automatic Memory Manager (3GB for database + 500M for other applications) to work. This part must be executed as root.

Add following line to “/etc/fstab” file

tmpfs /dev/shm tmpfs defaults,size=3584m 0 0

Resize /dev/shm size online

mount -o remount,size=3584M /dev/shm

4. Change initialization parameters for minimum database settings. Do all following commands as user oracle.

sqlplus / AS SYSDBA

alter system set processes=300              SCOPE=SPFILE;
alter system set memory_max_target=2G       SCOPE=SPFILE;
alter system set memory_target=2G           SCOPE=SPFILE;
alter system set shared_pool_size=300M      SCOPE=SPFILE;
alter system set session_cached_cursors=100 SCOPE=SPFILE;
alter system set sga_max_size=0G            SCOPE=SPFILE;
alter system set sga_target=0G              SCOPE=SPFILE;
alter system set pga_aggregate_target=0G    SCOPE=SPFILE;

--restart oracle instance.

5. Create directories for Enterprise Manager and Agent as user oracle

mkdir /ora01/app/oracle/em
mkdir /ora01/app/oracle/em_agent

6. Start installation as user oracle, remember to run command xhost+ as root.

xhost +
access control disabled, clients can connect from any host
mkdir install
unzip -d install
unzip -d install
unzip -d install
cd install

7.If you don’t want to get email after installation just uncheck “I wish to receive security updates via My Oracle Support” and click “Next” button

8. You should get following warning message just ignore it and click “Yes” button

9. Just check “Skip” option to ignore downloading latest patches and click “Next” button

10. You should see that prerequisite checks are started. If all is fine click “Next” button. If you see errors you need to correct them by reading installation logs.

11. I just select simple installation method and click “Next” button

12. You need to specify directory where you want to install Enterprise Manager software and host name. When it’s done click “Next” button.

13. On this page you need to specify Administration password.The password can be changed later for each components of EM12C. Additional you need to specify details about your database where repository of EM12C will be installed plus password for user SYS. When it’s done click “Next” button.

14. You can see such error so ignore it and click “Yes” button. Installer will fix it automatically.

15. In case you get following screen with warning you can ignore it or make appropriate suggestions. In my case my installation is very small so I can ignore it. Just click “OK” button to proceed.

16. You should see following screen with summary just before installation. You can read here some interesting informations like: space required by installation, installation directories etc. Just click “Install” button.

17. It can take a lot of time to install all required components. Just run some funny movie :), relax and wait.

18. As last step you need to run following script as user root. When the script is finished click “OK” button.

19. You should see installation report with details URL addresses for your EM12C.

Enterprise Manager Cloud Control URL:
Admin Server URL:

20. Just enter URL for EM12C cloud control and login as user sysman. password was specified in pt. 13.

21. You should see invitation screen where you can choose your preferred home page. For each layout you can click on “Preview” button before you make final decision. I’m DBA so I click “Preview” for Databases.

22. Preview screen for Databases. If you close it and click on “Select As My Home” that’s how will look your start screen.

23. As last step I add new entry to .bash_profile of user oracle for EM12C software and new aliases to quickly navigate. installation is complete.

[oracle@oel5 ~]$ envo
[oracle@oel5 ~]$ alias | grep ORACLE
alias cdo='cd $ORACLE_OMS'
alias cdoa='cd $ORACLE_OMS_AGENT'
alias cdob='cd $ORACLE_BASE'
alias cdoh='cd $ORACLE_HOME'
alias envo='env | grep ORACLE | sort'
alias tns='cd $ORACLE_HOME/network/admin'

24. Quick commands for EM12C – all as user oracle

--start all
$ORACLE_OMS/bin/emctl start oms 
$ORACLE_OMS_AGENT/bin/emctl start agent
# Stop everything
$OARCLE_OMS/bin/emctl stop oms -all
$OARCLE_OMS_AGENT/bin/emctl stop agent

25. It’s time add some new targets to monitor in EM12C. If you click in menu Targets->Database you won’t see any database.It could be surprise for you because we have on our host

To add this database click “Add” button.

26. Now you need to enter host where your database is installed. In my case it’s Remember agent EM12C must be installed on the host to discover the database !!!. In my case it was installed during installation of EM12C. Then click “Continue” button.

26. As you can see new 3 targets are discovered on by agent EM12C:
asm instance:

Now you need to configure communication between targets and EM12C. To do this just click on “Configure” for database and later for ASM instance.

27.You need to enter password for user DBSNMP to establish communication between database and EM12C. If you don’t know password for user DBSNMP you can always change it via sqlplus. There is possibility to test connection by clicking “Test Connection”. When you are done click “Next” button.

28. Just click “OK” button

29. You need to enter SYSDBA password for instance +ASM. Then click “OK” button.

30. Now when connection is established and verified save your new targets by clicking “Save” button.

31. Summary screen new targets saved. Click “OK” button.

32. After selecting Targets->Databases you should see list of your databases. Just click on entry now you should see details about your database.

Have a fun 🙂


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