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Real Application Cluster(RAC) Interview Questions Part 3

1.How would to find location of OCR file when CRS is down?

If you need to find the location of OCR (Oracle Cluster Registry) but your CRS is down.

Look into “ocr.loc” file, location of this file changes depending on the Operating System

On Linux: /etc/oracle/ocr.loc

On Solaris: /var/opt/oracle/ocr.loc

If CRS is UP and Running
Set ASM environment or CRS environment then run the below command:




2.In 2 node RAC, how many NIC’s are used ?

2 network cards on each clusterware node
Network Card 1 (with IP address set 1) for public network
Network Card 2 (with IP address set 2) for private network (for inter node communication between rac nodes used by clusterware and rac database)



3.In 2 node RAC, how many IP’s are using ?

6 IP adress are required
## eth1-Public: 2
## eth0-Private: 2
## VIP: 2



5.What is difference between RAC ip addresses ?

  • Public IP address is the normal IP address typically used by DBA and System Administrator to manage storage, system and database.
  • Public IP addresses are reserved for the Internet.
  • Private IP address is used only for internal clustering processing (Cache Fusion) .
  • Private IP addresses are reserved for private networks.
  • VIP is used by database applications to enable fail over when one cluster node fails.



6.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)



7.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.


8.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



9.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



10.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.



11.What is an OCFS2?

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



12.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.



13.Do you know another Cluster Vendor?

  • HP Tru64 Unix
  • Veritas
  • Microsoft



 14.What is a raw device?

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



16.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.



17.When to use raw over CFS?

Always when CFS is not available or not supported by Oracle. 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.



18.What CRS is?

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.



19.Do we have to have Oracle RDBMS on all nodes?

Each node of a cluster that is being used for a clustered database will typically have the RDBMS and RAC software loaded on it, but not actual data files (these need to be available via shared disk).



20.What are the restrictions on the SID with a RAC database? Is it limited to 5 characters?

The SID prefix in 10g Release 1 and prior versions was restricted to five characters by install/ config tools so that an ORACLE_SID of up to max of 5+3=8 characters can be supported in a RAC environment. The SID prefix is relaxed up to 8 characters in 10g Release 2, see bug 4024251 for more information.



About Syed

As a certified and experienced Oracle Database Administrator with Almost 10 Years of Experience I am able to perform all levels of database maintenance and am fully qualified to do Oracle updates as well. Capitalizing on my interest in Business & IT both, I chose to navigate my career towards Enterprise Solutions, which has enabled me to excel in the combination of both. I have developed exceptional analytical skills that allow me to diagnose and take care of issues immediately. Extremely skilled in planning and execution of special projects in time- critical environments. Extensive knowledge in directing, coordinating and exercising concern authority for planning, organization, control and successful completions. Very skilled at solving customer relations issues by seeking first to understand and then to be understood. Effectively able to communicate with customers, vendors and management.

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