The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.

4.12 Installing a Btrfs root File System

For compatibility reasons, the default installation image of Oracle Linux boots the Red Hat compatible kernel to perform the installation. Oracle provides an alternative installation image (UEK Boot ISO) that supports the installation of Oracle Linux 6 Update 3 or later using the Unbreakable Enterprise Kernel (UEK) as the installation kernel. This installation method allows you to create a btrfs root file system.

As the UEK Boot ISO contains only the bootable installation image, you must set up a network installation server for the RPM packages. This server must have sufficient storage space to host the full Oracle Linux Release 6 Update 3 or later Media Pack DVD image (approximately 3.5 GB), and you must configure it to serve the image files using either NFS or HTTP to the target system on which you want to install Oracle Linux 6 Update 3 or later.