Oracle Real Application Cluster (RAC) Interview Questions - Part:3

1. Is it possible to use ASM for the OCR and voting disk?
No, the OCR and voting disk must be on raw or CFS (cluster file system).

2. Can I change the name of my cluster after I have created it when I am using Oracle Clusterware?
No, you must properly uninstall Oracle Clusterware and then re-install.

3. What the O2CB is?

The O2CB is the OCFS2 cluster stack. OCFS2 includes some services. These services must be started before using OCFS2 (mount/ format the file systems).

4. What the OCR file is used for? 
OCR is a file that manages the cluster and RAC configuration.

5. What the Voting Disk file is used for?
The voting disk is nothing but a file that contains and manages information of all the node memberships.

Oracle RAC - VirtualNuggets

6. What is the recommended method to make backups of a RAC environment?

RMAN to make backups of the database, dd to backup your voting disk and hard copies of the OCR file.

7.  What command would you use to check the availability of the RAC system?
crs_stat -t -v (-t -v are optional)

8. What is the minimum number of instances you need to have in order to create a RAC?

You can create a RAC with just one server.

9.  Name two specific RAC background processes

RAC processes are: LMON, LMDx, LMSn, LKCx and DIAG.

10.  Can you have many database versions in the same RAC?

Yes, but Clusterware version must be greater than the greater database version.

11.  What was RAC previous name before it was called RAC?

OPS: Oracle Parallel Server

12.  What RAC component is used for communication between instances?
Private Interconnect.

13. What is the difference between normal views and RAC views?
A RAC view has the prefix ‘G’. For example, GV $SESSION instead of V$SESSION

14.  Which command will we use to manage (stop, start) RAC services in command-line mode?

15.  How many alert logs exist in a RAC environment?
A- One for each instance.

16. 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.

17. How do you backup voting disk ?

#dd if=voting_disk_name of=backup_file_name

18. How do I identify the voting disk location ?

#crsctl query css votedisk

19. How do I identify the OCR file location ?

check /var/opt/oracle/ocr.loc or /etc/ocr.loc ( depends upon platform)
or #ocrcheck

20. What is SCAN?

Single Client Access Name (SCAN) is s a new Oracle Real Application Clusters (RAC) 11g Release 2 feature that provides a single name for clients to access an Oracle Database running in a cluster. The benefit is clients using SCAN 

do not need to change if you add or remove nodes in the cluster.
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