Monday, 2 July 2018

Interview Q and A for Oracle Enterprise Manager Part - 1

1. What is Oracle Enterprise Manager Database Control / DB Console?
Oracle Enterprise Manager Database Control (DBConsole) is the Web-based interface for managing an Oracledatabase. The Web-based Database Control is the primary tool for managing your Oracle database. It is installed with the database. Using Database Control, you can perform administrative tasks such as creating schema objects (tables,views, indexes, and so on), managing user security, managing database memory and storage, backing up and recovering your database, and importing and exporting data. You can also view performance and status information about your database. It does provide a full set of administration and monitoring tools that allow administrators to quickly and effectively monitor and administer a single Oracle database environment (host server, listener anddatabase). Along with the Database console following components are installed.
* A web-based console that provides a GUI interface.
A local version of the management service that works with the local database.
* A local version of the management repository. The repository is installed in the local database, which is used to contain configuration and historical information for one, single database environment.
* A local version of the management agent that sends monitoring data to the local management service.

2. How do I get dbconsole software?
Dbconsole software is shipped along with the database installation, no separate software is required for Databasecontrol. Along with Standard database installation "Oracle Enterprise Manager Console DB 10.2.0.x.0" component isinstalled which brings in the database console software.

3. How to install Enterprise manager database control software if not installed by default or is corrupt?
1. Run the latest Oracle Installer that is installed on the server.
2. Select the products.xml from the original RDBMS software distribution and the existing RBDMS Oracle Home when prompted.
3. Use the 'Custom' installation method and select the Enterprise Manager, Database Control component. Proceed with the install.
4. After installation has succeeded, install the latest patchset once again. You need not perform any post-installation tasks if the patchset was applied previously.
5. Enterprise Manager can be configured for each database using <ORACLE_HOME>/bin/emca.
NOTE: with 11.2 you cannot install as a separate product, dbconsole is installed always rdbms software.

4. How many databases can be monitored using database control?
Only one database can be monitored using database console. Db console is configured for one database and can manage the same database for which it's configured. It's not possible to have multiple databases in single databaseconsole. To monitor multiple databases using single console need to use Enterprise Manager Grid control.

5. How many database console can be configured per server?
The DB Control has a limitation of 19 Database Control per machine, due to port conflicts with the AGENT_PORT,DBCONTROL_HTTP_PORT, RMI_PORT and JMS_PORT.

6. Where is the repository of database console hosted?
Dbconsole repository is created in the same database under SYSMAN schema. SYSMAN user is the repository ownerand is the super user for database console administration.

7. Is it possible to have database console repository in separate database?
NO, It's not possible to host the database console repository in separate database. Emca command creates thedbconsole repository in same database by default and there is no way to change this.

8. How to create/configure database control?
Database console can be configured for the database using DBCA UI tool and emca command line utility. Using DBCAone can configure the database to create/drop database console. Emca (Enterprise Manager Configuration Assistant) iscommand line utility, which has all the option to configure/create/drop database console.

9. How to access Dbconsole?
Dbconsole can be accessed using the URL from browser. By default the URL is of following format:
http://hostname:<port>/em    or  https://hostname:<port>/em
Dbconsole URL can be accessed using both http and https, in 10.2 and 11g database console is secured by default andthe URL is https by default. To get the exact URL one can adopt any of follow methods:
- Get the dbconsole URL using the command
ORACLE_HOME/bin/emctl status dbconsole
[bin]$ ./emctl status dbconsole
TZ set to US/Central
Oracle Enterprise Manager 10g Database Control Release 10.2.0.1.0
Copyright (c) 1996, 2005 Oracle Corporation. All rights reserved.
http://hostname:5500/em/console/aboutApplication
Oracle Enterprise Manager 10g is running.
------------------------------------------------------------------
Using above command note down the URL to access database console.
- Check the parameter REPOSITORY_URL in the file ORACLE_HOME/<hostname_SID>/sysman/config/emd.propeties
REPOSITORY_URL=http://hostname.oracle.com:1158/em/upload/
Using this parameter grab the Database control URL.
For a new install you can find the dbConsole URL in ORACLE_HOME/install/readme.txt, portlist.ini will tell you theconsole and agent ports.

10. How to start dbconsole?
On Unix
1. Set the ORACLE_HOME and ORACLE_SID
$ export ORACLE_HOME=<oracle home path>
$ export ORACLE_SID=<SID>
2. Start the dbconsole
$ ORACLE_HOME/bin/./emctl start dbconsole
On Windows
1. Set the ORACLE_HOME and ORACLE_SID
cmd> set ORACLE_HOME=<Oracle home path>
cmd> set ORACLE_SID=<SID
2. Start the dbconsole
cmd> ORACLE_HOME\bin\emctl start dbconsole

11. How to stop dbconsole?
On Unix
1. Set the ORACLE_HOME and ORACLE_SID
$ export ORACLE_HOME=<oracle home path>
$ export ORACLE_SID=<SID>
2. Start the dbconsole
$ $ORACLE_HOME/bin/emctl stop dbconsole
On Windows
1. Set the ORACLE_HOME and ORACLE_SID
cmd> set ORACLE_HOME=<oracle home path>
cmd> set ORACLE_SID=<SID>
2. Start the dbconsole
cmd> %ORACLE_HOME%\bin\emctl stop dbconsole

12. How to check status of different components of database console?
Following commands can be used to check the status of database console and agent.
Check the status of dbconsole
ORACLE_HOME\bin\emctl status dbconsole
Check the status of agent
ORACLE_HOME\bin\emctl status agent

13. What are the default ports used by database console?
DB Control UI
10gR1 10gR2
5500 1158
DB Control Agent
10gR1 10gR2
1830 3938
DB Control Remote Method Invocation (RMI)
10gR1 10gR2
5520

14. Where are the configuration files stored under oracle home?
All the dbconsole configuration files are stored under the directory named <hostname_SID> where hostname is thehostname of the server and SID is the SID of the database. This directory is created under oracle_home duringdbconsole creation. All the configuration and xml files are present under this directory for a dbconsole configuration.
Also one unique <hostname_sid> directory exists for each of the database console under oracle_home. If there are 2database running under same oracle_home then there are two directory created namely:
Hostname_SID1
Hostname_SID2

15. What are important configuration files for dbconsole?
emd.properties under ORACLE_HOME/<hostname_sid>/sysman/config/
This file contains all the operational parameters for the dbconsole Agent.
emoms.properties under ORACLE_HOME/<hostname_sid>/sysman/config/
This file contains all the operational parameters for the Dbconsole Management Service.
emomslogging.properties under ORACLE_HOME/<hostname_sid>/sysman/config/
This file holds the logging mode for Dbconsole service.
targets.xml under ORACLE_HOME/<hostname_sid>/sysman/emd/
This file contains the definition of targets like host, listener and database.

16. What is monitoring user for database console?
By default DBSNMP is the monitoring user for database console. This user is used by database console agent toconnect to the database and collect default metrics. The DBSNMP user is created during database creation and shouldbe solely used as monitoring user for database console.

17. How to change Dbconsole language to English?
Some information visible in dbconsole is based on the client browser setting (indeed the operating system language,namely, if the browser is used from a windows client). Even having everything switched to English the information in the dbconsole is shown translated into the OS language,even if the underlying info (from database table) is given in English as well;
To change the language to English refer Note.370178.1 How To Change The DB Console Language To English:

18. Is it possible to configure database console for a database running on Active/Passive High
Availability Environments?and how ?
Yes starting from 10.2.0.2 and above dbconsole can be configured for databases running on Active/Passive HighAvailability Environments. Note 362524.1 - Configure DB Control 10.2, 11g for use in Active/Passive High Availability Environments

19. While dropping and creating the database console do I need down time on production databases?
The emca command for 10g and 11.1 database, when recreating or dropping the repository, requires the database tobe quiesced. This means that, temporarily, no operations are possible on the database and new users cannot login.
If there are active sessions on the database at the time the quiesce operation will hang pending their completion,during which time no new users will be able to connect. Therefore it is important to understand that running these commands may/will cause the database to be unavailableduring the time that the repository is being dropped and should not be run on a production database unless you arefully aware of the possible impact to database availability and have planned for this eventuality

20. What action needs to be taken if the hostname or SID of the database server is changed?
If there is a hostname or SID change for the database server then the database console needs to be recreated. Thereis no other solution if the hostname or SID is changed other that recreating the database console. All database consoleconfiguration files are created under the hostname_sid directory and the configuration files along with the repositorykeeps reference of the hostname, which is why dbconsole needs to be reconfigured if there is change in hostname/sid.

21. Where are dbconsole files located and how to manage dbconsole log files?
Dbconsole log files are located at $ORACLE_HOME/<hostname>_<sid>/sysman/log/ and $ORACLE_HOME/oc4j/j2ee/OC4J_DBConsole_host_sid/log

22. How to reconfigure database console configuration files without loosing configuration information within the repository?
Yes it is possible to reconfigure only the configuration files without loosing database console repository database.

23. Is it possible to run emca command in silent mode? and how ?
Use emca commands can be executed in silent mode by passing the variables in response file.

24. What should be done if the hostname is changed where DBConsole is running? Or Why Dbconsole stops working if the hostname/domain name is changed?
DB Control is the standalone management tool for a 10g Database. The configuration files and repository used by DBControl contain specific information about the database, host and listener. If the Hostname, Domain name, or Listenerconfiguration changes after an installation, DB Control may consider those targets as being down or unavailablebecause it doesn't know about the new names or configuration. For this reason, you may have to (from time-to-time)recreated the DB Control configuration files and repository

25. How to run EMCA commands I silent mode?
EMCA can use a response file to populate the required values. By using a response file, you can basically run EMCA insilent (non-interactive) mode. Create a response file that includes the values to be passed to EMCA. The file can be named any name that followsstandard file naming procedures.

26. How to setup Database Control for SSL (HTTPS) secure connection?
In 10.2 the database console is secure by default, but if it's required to secure and unsecure the database console manually use following commands:
To secure dbconsole
emctl secure dbconsole
To Unsecuredbconsole
emctl unsecure dbconsole

27. How to change password of MGMT_VIEW user for database console?
MGMT_VIEW is an internal user used by database console for which the password is set at the time of dbconsoleconfiguration. Normally there is no need to reset the password for this user as its never required and known toexternal user.Note.1369157.1

28. How dbconsole is deployed on RAC database having multiple instances?
In 10.2.x.x ,11.1.x.x Database release, DB Control on a RAC cluster with n nodes, a dbconsole is installed only on thenode from which the DB Control is deployed. One agent on each node is deployed to reports to that same uniquedbconsole management service. It is however possible to later reconfigure the DB Control to have more than one dbconsole started and to have agentsreporting to several dbconsole. In 10.1.x.x a dbconsole is deployed on each node of the cluster. Each agent on each node reported to each dbconsolemanagement service on the same node.

29. How to check Dbconsole RAC configuration using emca? Or How to find the Dbconsole upload
host in cluster Dbconsole configuration?
To check the DB Control configuration on the cluster:
$emca -displayConfigdbcontrol -cluster
INFO:
**************** Current Configuration ****************
INSTANCE NODE DBCONTROL_UPLOAD_HOST
---------- ---------- ---------------------
EM1021 node1 node1.mycompany.com
EM1022 node2 node1.mycompany.com
EM1023 node3 node1.mycompany.com
Using this command check the dbconsole upload host for each node.

30. How remove an instance from DB Control monitoring?
If you plan to remove an instance from the RAC database, you must first remove the instance from DB Controlmonitoring.You can also remove an instance from DB Control monitoring simply because you are not interested to monitor thisparticular instance.
Removing an instance from DB Control monitoring does not remove the instance from the RAC database.This command can be run from any node in the cluster, except from the node from where runs the instance for whichwe want to stop the monitoring.
For example if we want to stop monitoring the instance on node2, we can run the following command either fromnode1 or from node3:
$ emca -deleteInstdb
Enter the following information:
Node name: node2
Database unique name: EM102
Database SID: EM102

31. How to add an instance to RAC DB Control monitoring?
If you have added an instance to the RAC database and if you plan to monitor it with the DB Control, you must add theinstance to DB Control monitoring.
$ emca -addInstdb
Enter the following information:
Node name: node2
Database unique name: EM102
Database SID: EM1022

32. How to drop DB Control configuration file keeping the repository?
$ emca -deconfigdbcontroldb # For standalone database
$ emca -deconfigdbcontroldb -cluster # For a cluster database
Enter the following information:
- Database unique name
This emca command does the following:
- stop the DB Control (dbconsole, agent) on all nodes of the cluster
- remove all DB Control related directories on all nodes of the cluster

33. How to set preferred credentials from dbconsole.
1. Login to the database console from browser.
2. Go to Preferences at the top of the Database Home page.
3. Click on Preferred Credentials in the left hand pane.
4. Here the preferred credentials screen will appear for the database host and listener targets.
5. Click on Set Credentials column corresponding to each of the target and fill in the credentials.
6. After filling the credentials Click on test, if test is successful click on Apply.

34. How to define blackout in dbconsole
1. Login to the dbconsole as administrator user.
2. Click on Setup.
3. Click on Blackout in the left pane.
4. Click on the Create Button to launch the blackout creation Wizard.
5. Enter the blackout name, select the target and click on Next.
6. Define the blackout schedule on the schedule step and click on Next.
7. Review the settings and click on Finish button. You will receive confirmation message for the blackout created.
8. Later you can view the blackout settings from the blackout page clicking on theViewbuttton.

35. How to enable/disable Management Pack from Dbconsole?
To control Management Pack Access go to Setup -> Management Pack Access.
Select appropriate option and click on Apply. With 10G Dbconsole following management packs are available.
Database Diagnostics Pack
Database Tuning Pack
Database Configuration Pack

36. How to launch iSQL*Plus from DBconsole?
iSQL*Plus can be launched directly from dbconsole. Go to the DBconsole home page and click on the link "iSQL*Plus"under "Related Links". Note that iSQL*Plus service should be running.

37. How to monitor Alert Log Content from dbconsole?
Latest entries in alert log file can be monitored using dbconsole. Go to Dbconsole Home page and click on "Alert LogContent" under "Related Links". The page launches the alert log content with most recent alert log entries. On thispage there is search option by start and end date.

38. How to configure dbconsole so that it use Dedicated Server Processes for connection to database?
This setting is currently not supported in any version of DB Console.

39. What is 'emdwgrd' Utility in 11g DBControl and how to use it ?
The emdwgrd utility is a script that saves/restores the Enterprise Manager 11g Database Control information. Thesave/restore feature is meant to be used as a workaround to allow downgrades for Enterprise Manager DatabaseControl when a database downgrade its required.
It is required that prior to upgrading database and EM, this script is executed to save the EM DB Control information.
Later if the database needs to be downgraded, you will be able to downgrade the EM DB Control also.
The emdwgrd utility resides in the ORACLE_HOME/bin directory in the Oracle Database 11g home. Note that this utilityis an 11g feature not available in 10g oracle homes

40. How to verify Database Console is installed and configured under oracle_home?
- Check output of "opatchlsinventory -detail" and following components should be installed.
Enterprise Manager Agent Core
Enterprise Manager Agent DB
Enterprise Manager Baseline
Enterprise Manager Common Files
Enterprise Manager Minimal Integration
Enterprise Manager plugin Common Files
Enterprise Manager plugin Common Files
Enterprise Manager Repository Core
Enterprise Manager Repository DB
If above components are installed it means the Dbconsole software is installed,
- Check the presence of <hostname_sid> under oracle_home and OC4J_DBConsole_<hostname>_<SID> underoracle_home/oc4j/j2ee, which confirm the dbconsole is configured for particular database.

41. How to change the default timeout session in dbconsole.
1. Stop the dbconsole
$ emctl stop dbconsole
2. Take a backup of emoms.properties file under $ORACLE_HOME/<hostname_sid>/sysman/config directory and add
the following line:
oracle.sysman.eml.maxInactiveTime=<time in minutes>
3. Update the web.xml in the $ORACLE_HOME/oc4j/j2ee/oc4j_applications/applications/em/em/WEB-INF with:
<session-config><session-timeout>-1</session-timeout></session-config>
-1 means no timeout
Any positive number means a number of minutes before the session gets logged out.
4. Then restart dbconsole.

emctl start dbconsole

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