Oracle DBA Interview Questions

Real time interview question which was asked to one of our group member. 

Tell me about your self

What is your roles and responsibility in your organization?

Listed down topic wise questions:

Oracle Architecture

Explain Oracle architecture

What are the background processes?

What is the physical and logical structure in oracle?

Difference between SGA and PGA.

What is the use of temporary tablespace?

What if someone drop temporary tablespace?

Which process is responsible to write data to disk?

RAC

What is OCR and voting disk files?

How many disk should be configured for OCR and Voting disk?

RAC start-up sequence

What is cache fusion?

What is split-brain situation and how to overcome from it?

Explain 5 RAC processes


Oracle Exadata Cell Commands

Cell Details

CellCLI> list cell
CellCLI> list cell detail
CellCLI> list cell attributes all
CellCLI> alter cell shutdown services rs
CellCLI> alter cell restart services rs
CellCLI> list cell attributes rsStatus
CellCLI> alter cell shutdown services MS
CellCLI> alter cell shutdown services CELLSRV
CellCLI> alter cell shutdown services all
CellCLI> alter cell restart services all
CellCLI> alter cell led on
CellCLI> drop cell
CellCLI> drop cell force

Physical Disk Details
         
CellCLI>list physicaldisk attributes all
CellCLI>describe physicaldisk 
CellCLI>list physicaldisk
CellCLI>list physicaldisk detail


Basic Linux Commands for Oracle

Listed down some of the basic commands which will help you while administering or implementing Oracle on linux.

Password Files: #cat /etc/passwd

Group File: #/etc/group

Create User: #useradd

Delete User: #userdel

Modify User Account : #usermod

Performance Monitor: #top

System Activity Reporter: #sar

Virtual Memory Statistics: #vmstat

IO Statistics: #iostat

Display Swap Size: #free

Activate Swap: #swapon -a


Oracle ASM on Linux

ASM RPMs would be required to configure ASM utility on Linux.

This demo has been done on RHEL 5 x86_64 bit.

1. Install RPMs.

#rpm -ivh oracleasm-2.6.18-238.el5-2.0.5-1.el5.x86_64.rpm
#rpm -ivh oracleasm-2.6.18-238.el5debug-2.0.5-1.el5.x86_64.rpm
#rpm -ivh oracleasm-2.6.18-238.el5xen-2.0.5-1.el5.x86_64.rpm
#rpm -ivh oracleasm-support-2.1.4-1.el5.x86_64.rpm

2. Configure ASM 

#/etc/init.d/oracleasm configure

Here we have to provide which user and group would be configured for ASM disk. Also it required to mention whether ASM driver should be auto-start or not.

Now ASM utility has been installed and configured on Linux.

You can also configure YUM Repository to install rpms for ASM utility.

How to kill all oracle processes in Linux ?

For Single Instance

$ps -ef|grep "ora_"|grep -v grep|grep $ORACLE_SID|awk '{print $2}'|xargs kill -9

For all instances

$ps -ef|grep "ora_"|grep -v grep|awk '{print $2}'|xargs -i kill -9 {}

YUM Configuration in Linux

Installing RPMs in Linux is very smooth but many times it headache to install all the dependency.

To remove this headache, RHEL comes with YUM utility which automatically takes all the dependency RPMs and installs it smoothly.


Step by step procedure to configure YUM

1. Mount REDHAT Operating System DVD/ISO on the server


2. Make a directory to store rpms from REDHAT DVD/ISO and copy Server directory from mounted DVD/ISO to folder created folder, which will copy all RPMs to local system.


3. Install createrepo RPM which required for YUM repository creation.