Introduction
Oracle Enterprise Manager (OEM) is Oracle's unified management platform for overseeing the full Oracle technology stack. It enables administrators to monitor, configure, and optimize Oracle Databases, Oracle Middleware, Oracle Applications, and Oracle Engineered Systems from a single console. OEM streamlines critical operations such as patching, configuration management, performance diagnostics, and lifecycle automation, keeping Oracle workloads secure, reliable, and high-performing. This article walks through configuring OEM on a Linux environment step by step.
Prerequisites
Below are the minimum requirements for a Linux environment:
- CPU: 2 cores
- RAM: 10GB
- Disk space: 45GB (/u01) and 50GB (/oem)
- OEM binary, downloadable here.
- Root user or sudo access.
- Firewall disabled.
Environment Used in This Guide
| Hostname | oem.oraeasy.com / 192.168.1.33 |
|---|---|
| OS | OL 7.3 |
| OEM Version | 13c Release 5 (13.5) |
| OMS Home | /oem/app/oracle/middleware |
| Agent Base | /oem/app/oracle/agent |
| Repository Database Name | OEMDB |
| Database Version | 19.27.0 |
| Oracle Home | /u01/app/oracle/product/19c/db_home |
Step 1: Verify Redo Log Groups
The repository database needs enough redo log groups to avoid log file sync waits during installation. Check the current group count and size, add more groups if needed, then retire the undersized originals.
SQL> select name,open_mode,log_mode from v$database;
NAME OPEN_MODE LOG_MODE
--------- -------------------- ------------
OEMDB READ WRITE ARCHIVELOG
SQL> SELECT group#, status,bytes/1024/1024 AS size_mb FROM v$log ORDER BY group#;
GROUP# STATUS size_mb
---------- --------- ------
1 INACTIVE 200
2 CURRENT 200
3 INACTIVE 200
SQL> ALTER DATABASE ADD LOGFILE GROUP 4 '/u01/app/oracle/oradata/OEMDB/redo04.log' SIZE 1G;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE GROUP 5 '/u01/app/oracle/oradata/OEMDB/redo05.log' SIZE 1G;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE GROUP 6 '/u01/app/oracle/oradata/OEMDB/redo06.log' SIZE 1G;
Database altered.
SQL> SELECT group#, status FROM v$log ORDER BY group#;
GROUP# STATUS
---------- ----------------
1 INACTIVE
2 CURRENT
3 INACTIVE
4 UNUSED
5 UNUSED
6 UNUSED
6 rows selected.
SQL> ALTER DATABASE DROP LOGFILE GROUP 1;
Database altered.
SQL> alter system switch logfile;
System altered.
SQL> SELECT group#, status FROM v$log ORDER BY group#;
GROUP# STATUS
---------- ----------------
2 ACTIVE
3 INACTIVE
4 ACTIVE
5 ACTIVE
6 CURRENT
SQL> ALTER DATABASE DROP LOGFILE GROUP 3;
Database altered.
SQL> alter system checkpoint;
System altered.
SQL> SELECT group#, status FROM v$log ORDER BY group#;
GROUP# STATUS
---------- ----------------
2 INACTIVE
4 INACTIVE
5 CURRENT
6 INACTIVE
SQL> ALTER DATABASE DROP LOGFILE GROUP 2;
Database altered.
SQL> ALTER DATABASE ADD LOGFILE GROUP 7 '/u01/app/oracle/oradata/OEMDB/redo07.log' SIZE 1G;
Database altered.
SQL> SELECT group#, status FROM v$log ORDER BY group#;
GROUP# STATUS
---------- ----------------
4 INACTIVE
5 CURRENT
6 INACTIVE
7 UNUSED
Step 2: Verify the TNS Service and SYS Password
Confirm the repository database is reachable over the network and that the SYS credentials work before starting the installer.
[oracle@oem ~]$ tnsping oemdb
TNS Ping Utility for Linux: Version 19.0.0.0.0 - Production on 16-AUG-2025 12:25:05
Copyright (c) 1997, 2025, Oracle. All rights reserved.
Used parameter files:
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = oem.oraeasy.com)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = oemdb)))
OK (10 msec)
[oracle@oem ~]$
[oracle@oem ~]$ sqlplus sys@oemdb as sysdba
SQL*Plus: Release 19.0.0.0.0 - Production on Sat Aug 16 12:25:09 2025
Version 19.27.0.0.0
Copyright (c) 1982, 2024, Oracle. All rights reserved.
Enter password:
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.27.0.0.0
SQL> def
DEFINE _DATE = "16-AUG-25" (CHAR)
DEFINE _CONNECT_IDENTIFIER = "oemdb" (CHAR)
DEFINE _USER = "SYS" (CHAR)
DEFINE _PRIVILEGE = "AS SYSDBA" (CHAR)
DEFINE _SQLPLUS_RELEASE = "1927000000" (CHAR)
DEFINE _EDITOR = "vi" (CHAR)
DEFINE _O_VERSION = "Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.27.0.0.0" (CHAR)
DEFINE _O_RELEASE = "1927000000" (CHAR)
SQL>
SQL> select name,open_mode from v$database;
NAME OPEN_MODE
--------- --------------------
OEMDB READ WRITE
Step 3: Adjust Repository Database Parameters
OEM's repository has a specific set of parameter requirements. Back up the current settings with a pfile first, then apply the changes and bounce the database.
SQL> select name,open_mode,log_mode from v$database;
NAME OPEN_MODE LOG_MODE
--------- -------------------- ------------
OEMDB READ WRITE ARCHIVELOG
SQL> create pfile='/home/oracle/oemdb.ora' from spfile;
File created.
SQL> show parameter _allow_insert_with_update_check
SQL> show parameter session_cached_cursors
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
session_cached_cursors integer 50
SQL> show parameter shared_pool_size
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
shared_pool_size big integer 0
SQL> show parameter processes
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 1
db_writer_processes integer 1
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 40
log_archive_max_processes integer 4
processes integer 300
SQL>
SQL> show parameter "_allow_insert_with_update_check"
SQL> alter system set "_allow_insert_with_update_check"=true scope=both;
System altered.
SQL> alter system set session_cached_cursors=200 scope=spfile;
System altered.
SQL> alter system set shared_pool_size=600M scope=spfile;
System altered.
SQL> show parameter pga
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_limit big integer 2G
pga_aggregate_target big integer 0
SQL>
SQL> alter system set processes=600 scope=spfile;
System altered.
SQL> shut immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>
SQL> startup
ORACLE instance started.
Total System Global Area 1979711112 bytes
Fixed Size 8941192 bytes
Variable Size 1358954496 bytes
Database Buffers 603979776 bytes
Redo Buffers 7835648 bytes
Database mounted.
Database opened.
SQL>
SQL> show parameter _allow_insert_with_update_check
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
_allow_insert_with_update_check boolean TRUE
SQL> show parameter session_cached_cursors
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
session_cached_cursors integer 200
SQL> show parameter shared_pool_size
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
shared_pool_size big integer 608M
SQL>
SQL> show parameter processes
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 1
db_writer_processes integer 1
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 40
log_archive_max_processes integer 4
processes integer 600
Step 4: Create Required Directories and Place the Binary
[oracle@oem ~]$ mkdir -p /oem/app/oracle/middleware
[oracle@oem ~]$ mkdir -p /oem/app/oracle/agent
[oracle@oem ~]$
[oracle@oem ~]$ ll /oem/app/oracle/
total 0
drwxr-xr-x. 2 oracle oinstall 6 Aug 16 12:18 agent
drwxr-xr-x. 2 oracle oinstall 6 Aug 16 12:18 middleware
[oracle@oem ~]$
[oracle@oem ~]$ cd /oem/software/
[oracle@oem software]$
[oracle@oem software]$ ls -lrth
total 8.0G
-rwxrwxr-x. 1 oracle oinstall 1.5G Aug 16 12:19 em13500_linux64.bin
-rwxrwxr-x. 1 oracle oinstall 1.8G Aug 16 12:19 em13500_linux64-2.zip
-rwxrwxr-x. 1 oracle oinstall 2.0G Aug 16 12:19 em13500_linux64-3.zip
-rwxrwxr-x. 1 oracle oinstall 1.4G Aug 16 12:19 em13500_linux64-4.zip
-rwxrwxr-x. 1 oracle oinstall 1.4G Aug 16 12:19 em13500_linux64-5.zip
[oracle@oem software]$
Step 5: Start the Installation
The installer needs about 12GB of free space to extract into. If /tmp doesn't have that much, point it at another location with enough room.
[oracle@oem software]$ pwd
/oem/software
[oracle@oem software]$
[oracle@oem software]$ ./em13500_linux64.bin
ERROR: Temporary directory /tmp does not have enough free space. At least 12289 MB of free space are required.
Please input another directory or [Exit]: /u01/software/temp
Launcher log file is /u01/software/temp/OraInstall2025-08-16_12-28-40PM/launcher2025-08-16_12-28-40PM.log.
Extracting the installer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Done
Checking monitor: must be configured to display at least 256 colors. Actual 16777216 Passed
Checking swap space: must be greater than 512 MB. Actual 4095 MB Passed
Checking if this platform requires a 64-bit JVM. Actual 64 Passed (64-bit not required)
Preparing to launch the Oracle Universal Installer from /u01/software/temp/OraInstall2025-08-16_12-28-40PM
ScratchPathValue :/u01/software/temp/OraInstall2025-08-16_12-28-40PM
Aug 16, 2025 12:34:18 PM org.apache.sshd.common.io.DefaultIoServiceFactoryFactory getIoServiceProvider
INFO: No detected/configured IoServiceFactoryFactory using Nio2ServiceFactoryFactory
.......................................................................................
Step 6: Walk Through the OEM Installer
Now the GUI installer window will open. Follow the steps below.
Select Advanced Install, then click Next.
Select Skip, then click Next.
Click Ignore to dismiss the prerequisite warnings.
Click Next.
Provide the OMS Home, Agent Base directory, and OEM server hostname, then click Next.
Click Next.
Provide the password, then click Next.
Provide the repository database details, then click Next.
Click Auto Fix.
Click Next.
Click OK.
Provide the SYSMAN and Agent Registration passwords, then click Next.
Click Next.
Click Next.
Review the details, then click Install.
Note: The full installation can take 5-6 hours. Keep an eye on the database alert log during this stretch to catch any failure early.
Monitor the installation progress and related logs.
If the installation appears to hang at this stage, as shown below, check whether the SYSMAN schema's optimizer statistics are locked and gather them if needed.
Check Whether Stats Are Locked:
SQL> SELECT stattype_locked FROM dba_tab_statistics WHERE owner = 'SYSMAN';
STATT
-----
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
....
....
....
5930 rows selected.
Unlock the Stats and Gather Them:
SQL> EXEC DBMS_STATS.unlock_schema_stats('SYSMAN');
PL/SQL procedure successfully completed.
SQL> SELECT stattype_locked FROM dba_tab_statistics WHERE owner = 'SYSMAN';
STATT
-----
....
....
....
5930 rows selected.
SQL> EXEC DBMS_STATS.gather_schema_stats('SYSMAN');
PL/SQL procedure successfully completed.
Wait a while and the installation will move forward.
Execute the script as the root user, then click OK.
[root@oem ~]# /oem/app/oracle/middleware/allroot.sh
Starting to execute allroot.sh .........
Starting to execute /oem/app/oracle/middleware/root.sh ......
Check /oem/app/oracle/middleware/install/root_oem.oraeasy.com_2025-08-16_18-19-43.log for the output of root script
Finished product-specific root actions.
/etc exist
Finished execution of /oem/app/oracle/middleware/root.sh ......
Starting to execute /oem/app/oracle/agent/agent_13.5.0.0.0/root.sh ......
Finished product-specific root actions.
/etc exist
Finished execution of /oem/app/oracle/agent/agent_13.5.0.0.0/root.sh ......
[root@oem ~]#
Installation is now complete. Review the details, then click Close.
Step 7: Check the OMS and Agent Status
[oracle@oem ~]$ cd /oem/app/oracle/middleware/bin
[oracle@oem bin]$ ./emctl status oms
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
WebTier is Up
Oracle Management Server is Up
JVMD Engine is Up
[oracle@oem bin]$
[oracle@oem bin]$ ./emctl status oms -details
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
Enter Enterprise Manager Root (SYSMAN) Password :
Console Server Host : oem.oraeasy.com
HTTP Console Port : 7788
HTTPS Console Port : 7803
HTTP Upload Port : 4889
HTTPS Upload Port : 4903
EM Instance Home : /oem/app/oracle/gc_inst/em/EMGC_OMS1
OMS Log Directory Location : /oem/app/oracle/gc_inst/em/EMGC_OMS1/sysman/log
OMS is not configured with SLB or virtual hostname
Agent Upload is locked.
OMS Console is locked.
Active CA ID: 1
Console URL: https://oem.oraeasy.com:7803/em
Upload URL: https://oem.oraeasy.com:4903/empbs/upload
WLS Domain Information
Domain Name : GCDomain
Admin Server Host : oem.oraeasy.com
Admin Server HTTPS Port: 7102
Admin Server is RUNNING
Oracle Management Server Information
Managed Server Instance Name: EMGC_OMS1
Oracle Management Server Instance Host: oem.oraeasy.com
WebTier is Up
Oracle Management Server is Up
JVMD Engine is Up
[oracle@oem bin]$
[oracle@oem bin]$ cd /oem/app/oracle/agent/agent_13.5.0.0.0/bin
[oracle@oem bin]$ ./emctl status agent
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
---------------------------------------------------------------
Agent Version : 13.5.0.0.0
OMS Version : 13.5.0.0.0
Protocol Version : 12.1.0.1.0
Agent Home : /oem/app/oracle/agent/agent_inst
Agent Log Directory : /oem/app/oracle/agent/agent_inst/sysman/log
Agent Binaries : /oem/app/oracle/agent/agent_13.5.0.0.0
Core JAR Location : /oem/app/oracle/agent/agent_13.5.0.0.0/jlib
Agent Process ID : 3038
Parent Process ID : 2742
Agent URL : https://oem.oraeasy.com:3872/emd/main/
Local Agent URL in NAT : https://oem.oraeasy.com:3872/emd/main/
Repository URL : https://oem.oraeasy.com:4903/empbs/upload
Started at : 2025-08-16 19:21:59
Started by user : oracle
Operating System : Linux version 4.1.12-61.1.18.el7uek.x86_64 (amd64)
Number of Targets : 35
Last Reload : (none)
Last successful upload : 2025-08-16 20:04:16
Last attempted upload : 2025-08-16 20:04:16
Total Megabytes of XML files uploaded so far : 0.14
Number of XML files pending upload : 0
Size of XML files pending upload(MB) : 0
Available disk space on upload filesystem : 60.96%
Collection Status : Collections enabled
Heartbeat Status : Ok
Last attempted heartbeat to OMS : 2025-08-16 20:06:20
Last successful heartbeat to OMS : 2025-08-16 20:06:20
Next scheduled heartbeat to OMS : 2025-08-16 20:07:20
---------------------------------------------------------------
Agent is Running and Ready
[oracle@oem bin]$
Step 8: Log In to the OEM Console
Open the console URL and sign in with the SYSMAN credentials set during installation.
https://192.168.1.33:7803/em
Provide the credentials, then click Login.
Accept the license agreement.
This lands on the welcome page.
Click Enterprise, then Summary.
Step 9: Start and Stop OEM Services
These are the day-to-day commands for controlling OMS and the agent. Make sure the repository database and its listener are running before starting OMS.
Set the Environment:
[oracle@oem ~]$ export OMS_HOME=/oem/app/oracle/middleware
[oracle@oem ~]$ export AGENT_HOME=/oem/app/oracle/agent/agent_13.5.0.0.0
To Start:
[oracle@oem ~]$ $OMS_HOME/bin/./emctl start oms
[oracle@oem ~]$ $OMS_HOME/bin/./emctl start agent
To Stop:
[oracle@oem ~]$ $OMS_HOME/bin/./emctl stop oms
[oracle@oem ~]$ $OMS_HOME/bin/./emctl stop agent
Troubleshooting: OMS Fails to Start Due to a Missing Library
During this installation, OMS failed to start because of a missing shared library. The steps below walk through diagnosing and fixing that specific issue. If you hit the same error, don't close the installer GUI window while working through this.
Check the OEM Installer Log
INFO: oracle.sysman.top.oms:Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
INFO: oracle.sysman.top.oms:Starting Oracle Management Server...
INFO: oracle.sysman.top.oms:WebTier Could Not Be Started.
INFO: oracle.sysman.top.oms:Error Occurred: WebTier Could Not Be Started.
INFO: oracle.sysman.top.oms:Please check /oem/app/oracle/gc_inst/em/EMGC_OMS1/sysman/log/emctl.log for error details SEVERE:
oracle.sysman.top.oms:Starting of OMS failed.
Check the OHS Log
[oracle@oem bin]$ tail -50 /oem/app/oracle/gc_inst/user_projects/domains/GCDomain/system_components/OHS/ohs_nm.log
2025-08-16 16:16:06 INFO OHS-0 Domain initialized for /oem/app/oracle/gc_inst/user_projects/domains/GCDomain
2025-08-16 16:16:07 INFO OHS-4112 Creating instance ohs1
2025-08-16 16:16:10 INFO OHS-4114 Updating instance ohs1
2025-08-16 17:13:18 INFO OHS-4018 Starting server ohs1
2025-08-16 17:13:18 INFO OHS-0 Running /oem/app/oracle/middleware/ohs/bin/launch httpd -DOHS_MPM_WORKER -d /oem/app/oracle/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/components/OHS/instances/ohs1 -k start -f /oem/app/oracle/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/components/OHS/instances/ohs1/httpd.conf
2025-08-16 17:13:19 INFO OHS-0 /oem/app/oracle/middleware/ohs/bin/httpd: error while loading shared libraries: libclntshcore.so.12.1:
cannot open shared object file: No such file or directory
That's the root cause: OHS (Oracle HTTP Server) can't find the Oracle client library libclntshcore.so.12.1.
Confirm LD_LIBRARY_PATH in setDomainEnv.sh
[oracle@oem bin]$ cat /oem/app/oracle/gc_inst/user_projects/domains/GCDomain/bin/setDomainEnv.sh|grep LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
Link the libclntshcore Library File
The 19c home has a newer version of the same library under a different filename, so a symlink resolves the mismatch without installing anything extra.
[oracle@oem lib]$ ln -s /u01/app/oracle/product/19c/db_home/lib/libclntshcore.so.19.1 libclntshcore.so.12.1
[oracle@oem lib]$ ls -l /oem/app/oracle/middleware/ohs/lib/libclntshcore.so.*
lrwxrwxrwx. 1 oracle oinstall 61 Aug 16 17:56 /oem/app/oracle/middleware/ohs/lib/libclntshcore.so.12.1 -> /u01/app/oracle/product/19c/db_home/lib/libclntshcore.so.19.1
Stop and Start OMS Manually
[oracle@oem lib]$ cd /oem/app/oracle/middleware/bin
[oracle@oem bin]$ ./emctl stop oms -all
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
Stopping Oracle Management Server...
WebTier Could Not Be Stopped
Oracle Management Server Successfully Stopped
AdminServer Failed to be Stopped
Check Admin Server log file for details: /oem/app/oracle/gc_inst/user_projects/domains/GCDomain/servers/EMGC_ADMINSERVER/logs/EMGC_ADMINSERVER.out
Oracle Management Server is Down
JVMD Engine is Down
[oracle@oem bin]$
[oracle@oem bin]$ ./emctl start oms
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation. All rights reserved.
Starting Oracle Management Server...
WebTier Successfully Started
Oracle Management Server Successfully Started
Oracle Management Server is Up
JVMD Engine is Up
[oracle@oem bin]$
Click Retry on the Installer
With OMS confirmed running manually, go back to the still-open installer GUI window and click Retry to let it pick up where it left off.
Thank you for reading!
I hope this content has been helpful to you. Your feedback and suggestions are always welcome. Feel free to leave a comment or reach out with any queries.
Abhishek Shrivastava
Oracle DBA with hands-on experience managing production Data Guard, RAC, GoldenGate, and APEX environments. I write practical, tested installation and troubleshooting guides based on real deployment work.
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