July 24, 2013

Oracle DBA Interview Questions and Answers - Patching,Cloning and Upgrade

Oracle Patching,Cloning and Upgrade Interview Questions and Answers

When you moved oracle binary files from one ORACLE_HOME server to another server then which oracle utility will be used to make this new ORACLE_HOME usable?
Relink all.

In which months oracle release CPU patches?
JAN, APR, JUL, OCT

When we applying single Patch, can you use opatch utility?
Yes, you can use Opatch incase of single patch. The only type of patch that cannot be used with OPatch is a patchset.

Is it possible to apply OPATCH without downtime?
As you know for apply patch your database and listener must be down. When you apply OPTACH it will update your current ORACLE_HOME. Thus coming to your question to the point in fact it is not possible without or zero downtime in case of single instance but in RAC you can Apply Opatch without downtime as there will be more separate ORACLE_HOME and more separate instances (running once instance on each ORACLE_HOME).

You have collection of patch (nearly 100 patches) or patchset. How can you apply only one patch from it?
With Napply itself (by providing patch location and specific patch id) you can apply only one patch from a collection of extracted patch. For more information check the opatch util NApply –help. It will give you clear picture.
For Example:
opatch util napply <patch_location> -id 9 -skip_subset -skip_duplicate
This will apply only the patch id 9 from the patch location and will skip duplicate and subset of patch installed in your ORACLE_HOME.

If both CPU and PSU are available for given version which one, you will prefer to apply?
From the above discussion it is clear once you apply the PSU then the recommended way is to apply the next PSU only. In fact, no need to apply CPU on the top of PSU as PSU contain CPU (If you apply CPU over PSU will considered you are trying to rollback the PSU and will require more effort in fact). So if you have not decided or applied any of the patches then, I will suggest you to go to use PSU patches. For more details refer: Oracle Products [ID 1430923.1], ID 1446582.1

PSU is superset of CPU then why someone choose to apply a CPU rather than a PSU?
CPUs are smaller and more focused than PSU and mostly deal with security issues. It seems to be theoretically more consecutive approach and can cause less trouble than PSU as it has less code changing in it. Thus any one who is concerned only with security fixes and not functionality fixes, CPU may be good approach. 

How to Download Patches, Patchset or Opatch from metalink?

If you are using latest support.oracle.com then after login to metalink Dashboard
- Click on "Patches & Updates" tab
- On the left sidebar click on "Latest Patchsets" under "Oracle Server/Tools".
- A new window will appear.
- Just mouseover on your product in the "Latest Oracle Server/Tools Patchsets" page.
- Corresponding oracle platform version will appear. Then simply choose the patchset version and click on that.
- You will go the download page. From the download page you can also change your platform and patchset version.

REFERENCES:
http://docs.oracle.com/cd/E11857_01/em.111/e12255/e_oui_appendix.htm
Oracle® Universal Installer and OPatch User's Guide
11g Release 2 (11.2) for Windows and UNIX
Part Number E12255-11


What is the recent Patch applied?

What is OPatch?

How to Apply Opatch in Oracle?

1. You MUST read the Readme.txt file included in opatch file, look for any prereq. steps/ post installation steps or and DB related changes. Also, make sure that you have the correct opatch version required by this patch.
2.Make sure you have a good backup of database.
3. Make a note of all Invalid objects in the database prior to the patch.
4. Shutdown All the Oracle Processes running from that Oracle Home , including the Listener and Database instance, Management agent etc.
5. You MUST Backup your oracle Home and Inventory
tar -cvf $ORACLE_HOME $ORACLE_HOME/oraInventory | gzip > Backup_Software_Version.tar.gz
6. Unzip the patch in $ORACLE_HOME/patches
7. cd to the patch direcory and do opatch -apply to apply the patch.
8. Read the output/log file to make sure there were no errors.

Patching Oracle Software with OPatch ?

opatch napply <patch_location> -skip_subset -skip_duplicate
OPatch skips duplicate patches and subset patches (patches under <patch_location> that are subsets of patches installed in the Oracle home).

What is Opactch in Oracle?

OPATCH Utility (Oracle RDBMS Patching)

1. Download the required Patch from Metalink based on OS Bit Version and DB Version.
2. Need to down the database before applying patch.
3. Unzip and Apply the Patch using ”opatch apply” command.On successfully applied of patch you will see successful message “OPatch succeeded.“, Crosscheck your patch is applied by using “opatch lsinventory” command .
4. Each patch has a unique ID, the command to rollback a patch is “opatch rollback -id  <patch no.>” command.On successfully applied of patch you will see successful message “OPatch succeeded.“, Crosscheck your patch is applied by using “opatch lsinventory” command .
5. Patch file format will be like, “p<patch no.>_<db version>_<os>.zip”
6. We can check the opatch version using “opatch -version” command.
7. Generally, takes 2 minutes to apply a patch.
8. To get latest Opatch version download “patch 6880880 - latest opatch tool”, it contains OPatch directory.
9. Contents of downloaded patches will be like “etc,files directories and a README file”
10. Log file for Opatch utility can be found at $ORACLE_HOME/cfgtoollogs/opatch
11. OPatch also maintains an index of the commands executed with OPatch and the log files associated with it in the history.txt file located in the <ORACLE_HOME>/cfgtoollogs/opatch directory.
12. Starting with the 11.2.0.2 patch set, Oracle Database patch sets are full installations of the Oracle Database software. This means that you do not need to install Oracle Database 11g Release 2 (11.2.0.1) before installing Oracle Database 11g Release 2 (11.2.0.2).
13. Direct upgrade to Oracle 10g is only supported if your database is running one of the following releases: 8.0.6, 8.1.7, 9.0.1, or 9.2.0. If not, you will have to upgrade the database to one of these releases or use a different upgrade option (like export/ import).
14.Direct upgrades to 11g are possible from existing databases with versions 9.2.0.4+, 10.1.0.2+ or 10.2.0.1+. Upgrades from other versions are supported only via intermediate upgrades to a supported upgrade version.


Oracle version 10.2.0.4.0 what does each number refers to?
Oracle version number refers:
10 – Major database release number
 2 – Database Maintenance release number
 0 – Application server release number
 4 – Component Specific release number
 0 – Platform specific release number

Types of Patches?

How to rollback a patch?

What is PSU?

What is Rolling Patch?

How to check installed Patches?

How much time will it take for Patching?

Common issues faced in Patching?

REFERENCES:
OPATCH Utility (Oracle RDBMS Patching)
http://avdeo.com/2008/08/19/opatch-utility-oracle-rdbms-patching/

How to apply Database Patches
http://rafioracledba.blogspot.in/search/label/Database%20Patches

Critical Patch Updates, Security Alerts and Third Party Bulletin
http://www.oracle.com/technetwork/topics/security/alerts-086861.html

Oracle: Quick Guide to Opatch - (Oracle Database Patching utility)
http://www.dbalifeline.com/content/oracle-quick-guide-opatch-oracle-database-patching-utility

How to Design an Effective Patch Management Process
http://www.computing.net/howtos/show/how-to-design-an-effective-patch-management-process/744.html

Oracle Database 11.2.0.2 Patch Set (English)
http://www.dbacomp.com.br/blog/?p=69

Apply Oracle CPUApr2010 – 9352191 for Oracle10.2.0.4 in Aix5L
http://hendrydasan.com/2010/05/21/apply-oracle-cpuapr2010-9352191-for-oracle10-2-0-4-in-aix5l/

Cloning
=======
What is Cloning?

How to do take RMAN Cloning? Explain Steps?

Upgrade
=======

What is rolling upgrade?It is a new ASM feature from Database 11g.ASM instances in Oracle database 11g release(from 11.1) can be upgraded or patched using rolling upgrade feature. This enables us to patch or upgrade ASM nodes in a clustered environment without affecting database availability.During a rolling upgrade we can maintain a functional cluster while one or more of the nodes in the cluster are running in different software versions.Rolling upgrade can be used only for Oracle database 11g releases(from 11.1).

Steps to Upgrade in Oracle ?

Manual upgrade which involves the following steps:
1.Backup the database.
2.In UNIX/Linux environments, set the $ORACLE_HOME and $PATH variables to point to the new 11g Oracle home.
3.Analyze the existing instance using the "$ORACLE_HOME/rdbms/admin/utlu111i.sql" script.
4.Start the original database using the STARTUP UPGRADE command and proceed with the upgrade by running the "$ORACLE_HOME/rdbms/admin/catupgrd.sql" script.
5.Recompile invalid objects.
6.Restart the database.
7.Run the "$ORACLE_HOME/rdbms/admin/utlu111s.sql" script and check the result of the upgrade.
8.Troubleshoot any issues or abort the upgrade.

What happens when you give "STARTUP UPGRADE"?

$sqlplus "/as sysdba"
SQL> STARTUP UPGRADE

Note:
----
The UPGRADE keyword enables you to open a database based on an earlier Oracle Database release. It also restricts logons to AS SYSDBAsessions, disables system triggers, and performs additional operations that prepare the environment for the upgrade.

You might be required to use the PFILE option to specify the location of your initialization parameter file.
Once the database is started in upgrade mode, only queries on fixed views execute without errors until after the catupgrd.sql script is run. Before running catupgrd.sql, queries on any other view or the use of PL/SQL returns an error.

What is the difference between startup Upgrade and Migrate ?

startup migrate:
---------------
Used to upgrade a database till 9i.

Startup Upgrade
---------------
From 10G  we are using startup upgrade to upgrade database.

What happens internally when you use startup upgrade/migrate?

It will adjust few database (init) parameters (irrespective of what you have defined) automatically to certain values in order to run upgrade scripts smoothely.
in other way..it will issue few alter statements to set certain parameters which are required to complete the upgrade scripts without any issues.

REFERENCE:
---------
Oracle® Database Upgrade Guide 11g Release 2 (11.2)
http://docs.oracle.com/cd/E11882_01/server.112/e23633/upgrade.htm

Common issues faced in Upgrade?

Error is related to timezone file

Started database in upgrade mode and fired catupgrd.sql :

SQL> startup upgrade
ORACLE instance started.
Total System Global Area 6413680640 bytes
Fixed Size                  2160112 bytes
Variable Size            1946159632 bytes
Database Buffers         4429185024 bytes
Redo Buffers               36175872 bytes
Database mounted.
Database opened.
SQL> @catupgrd.sql
DOC>#######################################################################
DOC>#######################################################################
DOC>
DOC>   The first time this script is run, there should be no error messages
DOC>   generated; all normal upgrade error messages are suppressed.
DOC>
DOC>   If this script is being re-run after correcting some problem, then
DOC>   expect the following error which is not automatically suppressed:
DOC>
DOC>   ORA-00001: unique constraint () violated
DOC>#
   FROM registry$database
        *
ERROR at line 2:
ORA-00942: table or view does not exist
This  error is related to timezone file  which must be version 4 for Oracle version 11g.If timezone is not version 4 than patch needs to be applied.
Query to check timezone file  is:
SQL> select * from v$timezone_file;
FILENAME        VERSION
———— ———-
timezlrg.dat          4
SQL> select * from v$timezone_file;
FILENAME        VERSION
———— ———-
timezlrg.dat          4
So I had correct version.I remember applying patch before upgrade.I got lucky because patch existed for version 10.2.0.3.
If there is no patch for your Oracle versions than patch can be download for similar version and  applied manually.
Instructions are below:
1. Download the identified patch.
2. Unzip the patch, and locate the 2 files timezone.dat and timezlrg.dat in the “files/oracore/zoneinfo” directory of the uncompressed patch (or from the relevant .jar file of a   patchset). If there is also a readme.txt in this location then make a note of this as well.
3. Backup your existing files in $ORACLE_HOME/oracore/zoneinfo – THIS CAN BE VITAL, DO NOT SKIP.
Note:
Before going on with step 4, make sure the current files are not in use.
On Windows the files will simply refuse to be removed when the are in use.
On Unix replacing the files whilst they are in use can cause the files to become corrupt. Use the fuser command before replacing the files to make sure they are not in use.
4. Copy the 2 .dat files and possibly the readme.txt file that were found in step 2 into the $ORACLE_HOME/oracore/zoneinfo directory.
5. Restart the database (in case of installation on a database), or restart the client applications (in case of client install). Note that the database did not need to be down before the time zone files were applied, but it does need to be restarted afterwards.

http://indiandba.blogspot.in/2012/01/error-is-related-to-timezone-file.html

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