Oracle Apps DBA Interview Questions

Oracle Apps DBA Interview Questions

 This is the Interview season, with lots of openings World Wide. I have listed some of the very common Apps DBA interview questions faced by me. The answers are listed after each question. All the Best.....!

Author – Akash Pramanik

Database Administrator in IBM

akash007.pramanik@gmail.com


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More Question Answers (more on RAC)

1. How to find the database/sqlplus version(R12 and R11) ?

 Ans : select banner from v$version;

2. Do you know some Cluster Vendor other than Oracle?
HP Tru64 Unix, Veritas, Microsoft

3. What is CRS?
Oracle RAC 10g Release 1 introduced Oracle Cluster Ready Services (CRS), a platform-independent set of system services for cluster environments. In Release 2, Oracle has renamed this product to Oracle Clusterware.

4. What is a raw partition?
A raw partition is a portion of a physical disk that is accessed at the lowest possible level. A raw partition is created when an extended partition is created and logical partitions are assigned to it without any formatting. Once formatting is complete, it is called cooked partition.

5. When to use CFS over raw?
A CFS offers:
- Simpler management
- Use of Oracle Managed Files with RAC
- Single Oracle Software installation
- Autoextend enabled on Oracle datafiles
- Uniform accessibility to archive logs in case of physical node failure
- With Oracle_Home on CFS, when you apply Oracle patches CFS guarantees that the updated Oracle_Home is visible to all nodes in the cluster.

Note: This option is very dependent on the availability of a CFS on your platform.

6. When to use raw over CFS?
- Always when CFS is not available or not supported by Oracle.
- The performance is very, very important: Raw devices offer best performance without any intermediate layer between Oracle and the disk.
Note: Autoextend fails on raw devices if the space is exhausted. However the space could be added online if needed.

7. What is VIP IP used for?
It returns a dead connection IMMIDIATELY, when its primary node fails. Without using VIP IP, the clients have to wait around 10 minutes to receive ORA-3113: “end of file on communications channel”. However, using Transparent Application Failover (TAF) could avoid ORA-3113.

8. How is possible to install a RAC if we don’t have a CFS?
This is possible by using a raw device.

9. What is a raw device?
A raw device is a disk drive that does not yet have a file system set up. Raw devices are used for Real Application Clusters since they enable the sharing of disks.

10. Where are the Clusterware files stored on a RAC environment?
The Clusterware is installed on each node (on an Oracle Home) and on the shared disks (the voting disks and the CSR file)

11. Where are the database software files stored on a RAC environment?

The base software is installed on each node of the cluster and the
database storage on the shared disks.

12. What kind of storage we can use for the shared Clusterware files?
- OCFS (Release 1 or 2)
- raw devices
- third party cluster file system such as GPFS or Veritas

13. What kind of storage we can use for the RAC database storage?
- OCFS (Release 1 or 2)
- ASM
- raw devices
- third party cluster file system such as GPFS or Veritas

14. What is a CFS?
A cluster File System (CFS) is a file system that may be accessed (read and write) by all members in a cluster at the same time. This implies that all members of a cluster have the same view.

15. What is an OCFS2?
The OCFS2 is the Oracle (version 2) Cluster File System which can be used for the Oracle Real Application Cluster.

16. Which files can be placed on an Oracle Cluster File System?
- Oracle Software installation (Windows only)
- Oracle files (controlfiles, datafiles, redologs, files described by the bfile datatype)
- Shared configuration files (spfile)
- OCR and voting disk
- Files created by Oracle during runtime

Note: There are some platform specific limitations.

17. How is possible to install a RAC if we don’t have a CFS?
This is possible by using a raw device.

18. What is a raw device?
A raw device is a disk drive that does not yet have a file system set up. Raw devices are used for Real Application Clusters since they enable the sharing of disks.

19. What is the Cluster Verification Utility (cluvfy)?

The Cluster Verification Utility (CVU) is a validation tool that you can use to check all the important components that need to be verified at different stages of deployment in a RAC environment.

20. What are Oracle Clusterware Components

Voting Disk — Oracle RAC uses the voting disk to manage cluster membership by way of a health check and arbitrates cluster ownership among the instances in case of network failures. The voting disk must reside on shared disk.

Oracle Cluster Registry (OCR) — Maintains cluster configuration information as well as configuration information about any cluster database within the cluster. The OCR must reside on shared disk that is accessible by all of the nodes in your cluster