Upgrade interview questions oracle database

1. Oracle database upgrade from version to version.

* 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).
* 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.

2. 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).

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

4. 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.

5.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.

Q Is it possible to upgrade to R12.1.1 from 11.5.9?

Yes
Applications R11.5.6 and below requires to first upgrade to R11.5.10.2/10gR2
Applications R11.5.7 and up can be directly upgraded to R12

But 11.5.9 cannot be upgraded to R12.2 directly.

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 Q What are the high-level steps for upgrading 11i to R12.1.3?

– Upgrade database 9.2.0.6 to 11.2.0.4 in 11i
* Upgrade database from 9.2.0.6 to 9.2.0.8 and then to 11.2.0.4.
* Apply all interoperability patches for EBS 11i to work with 11.2.0.4 database.
* Upgrade JDK/JRE to supported version.

– If you want to use R12 on 64 Bit, 11i Split configuration- Move 11g Database to Linux 6 64Bit.

* Install 64 Bit Database 11.2.0.4 software on the new 64-Bit Linux machine.
* Move 11i database from old Linux 32-bit to new Linux-64-bit machine and attach 11i application to new 64-Bit database.

– Upgrade 11i TO R12.1.1

* Prepare 11i database for upgrade (configuration, applying patches etc.).
* Install R12.1.1 upgrade filesystem on the same 64-Bit Linus machine that we configured earlier and where our database currently run.
* Configure R12.1.1 application with existing 11.2.0.4 64 Bit database.
– Upgrade R12.1.1 To R12.1.3

* Upgrade all ORACLE_HOMEs (database, forms 10.1.2, web 10.1.3)
* Upgrade R12.1.1 application to R12.1.3 on Linux 64 Bit machine.