Introduction
There are several tutorials on internet about this topic, I just show you the way that I used to install OL6.
You have to download the ISO file; you can download from OTN or Software Delivery Cloud. This tutorial will have the following parts:

• Virtual Machine on Virtual Box creation
• OL6’s Basic Installation
• Configuring SELinux
• Disable Firewall

Virtual Machine on Virtual Box creation
You have to check which software you will install and which infrastructure, for example if you are installing Real application cluster 12c you should have at least 4GB of RAM in each Virtual Machine. So this is a template that I use for all my installations test.

Go to the “New” button to create a New virtual machine

Set name and operating system, after that click in “Next” button

Set the amount of memory RAM, and click “Next” button (just take a look that I am using 4GB of RAM, it usually is enough for most of the oracle products configuration in testing environment)

Create the hard disk, select “create a virtual hard disk now” option then “Create” button

You can use “Expert Mode” to configuring everything. In my case I will use VMDK format for the disks and it’s going to have 100GB

After that make sure you have configured the network adapters (for RAC I usually add two Host-Only Adapter and one NAT), select the virtual machine settings and go to “Network” section

The last step for configuring VM is to set up the ISO OS file, you have to go to storage and select the file from “Attribute”

OL6’s Basic Installation
Start the virtual machine, and choose the option “Install or upgrade an existing system” press “Enter” .

You could check the disk (ISO file) before start the installation process, in this case I will “skip” this step.

In the welcome installation process, you have to press “next” button

Choose you language and press “Next” button

Select the keyboard for the system and press “Next” button

On the storage selection page, we will use “Basic Storage Devices” then “Next” button

On the warning message, you have to select “Yes, discard any data” button

Set the hostname in this case I will use host01.vidbaz.net and then press “Next” button

Select your time Zone and then press “Next” button

Set the Root Password, if you choose a weak password (like me) then you’re going to receive a message “Use Ayway”, and then press “Next” button

We will use “Use all space” option and also select “Review and modify partitioning layout” and then press “Next” button

You can adjust the partition, I have changed the lv_swap to 10GB so when you are okay with this press “Next” button

Press “Format” on the Warnings message

And a final warning press “Write changes for disk”

Select “Install boot loader on /dev/sda” or you can change and choose another device then press “Next” button

Now you have to choose the different respositories that you want to install, you can use the “Basic Server” or “Database Server” template, we will also customize the packged for install.

On Base system tab, choose the following:

• Base
• Console interente tools
• Debugging tools
• Directory Client
• Hardware monitoring utilities
• Java platform
• Large systems performance
• Network file system client
• Performance tools
• Perl support

On servers tab, choose the following

• Server platform
• System administration tools

To set up Gnome Desktop, on Desktops tab, choose the following:

• Desktop
• Desktop Platform
• Fonts
• General Purpose Desktop
• Graphical Adminitartion tools
• Input Methods
• Remote Desktop Clients
• X Windows System

On Applications tab, select Internet Browser

On Development tab, select Development Tools

On the UEK3 kernel repo, make sure “UEK3 kernel repo” option is selected

Wait until installation process finish

When it is finish, press “reboot” button

After the reboot, you will configure a few things more, so press the button “Forward” to continue

Agree the License and press “Forward” button

Set up software update you should select “No, I prefer to register at a later time” and press “Forward” button.

Select “No thanks, I’ll connect later” to continue with installation process

Finish updates setup, press “Forward” button

On create user you can create your personal user, I will use root only because this is just a test VM, press “Forward” and after that on the warning message press “Yes”.

When you’ve configured Date and Time, press “Forward” button

Do not enable Kdump, and press “Finish” button to finish the installation process

After that log in to the machine.

If you have any connectivity issue check if the network interfaces are connected, go to “System” > “Preferences” > Network Connections and check the interfaces select and edit them. Just make sure that “Connect automatically” is selected.

Configuring SELinux
Configure SELinux to permissive, you can open an terminal session and change it as the following
[root@host01 ~]# cat /etc/selinux/config

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing – SELinux security policy is enforced.
# permissive – SELinux prints warnings instead of enforcing.
# disabled – No SELinux policy is loaded.
SELINUX=enforcing
# SELINUXTYPE= can take one of these two values:
# targeted – Targeted processes are protected,
# mls – Multi Level Security protection.
SELINUXTYPE=targeted

[root@host01 ~]# vi /etc/selinux/config

[root@host01 ~]# cat /etc/selinux/config

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing – SELinux security policy is enforced.
# permissive – SELinux prints warnings instead of enforcing.
# disabled – No SELinux policy is loaded.
SELINUX=permissive
# SELINUXTYPE= can take one of these two values:
# targeted – Targeted processes are protected,
# mls – Multi Level Security protection.
SELINUXTYPE=targeted

[root@host01 ~]#

You can reboot your VM or you can run the following command from root terminal

[root@host01 ~]# setenforce Permissive

For more information, you can check the following MOS note: How to Disable or set SELinux to Permissive mode (Doc ID 457458.1)

Disable Firewall

Disable Firewall with the following commands:

[root@host01 ~]# service iptables stop
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Flushing firewall rules: [ OK ]
iptables: Unloading modules: [ OK ]
[root@host01 ~]# chkconfig iptables off
[root@host01 ~]# chkconfig –list iptables
iptables 0:off 1:off 2:off 3:off 4:off 5:off 6:off