Using GUID Partition Table (GPT) with Intel® RAID Controllers
The GUID Partition Table (GPT) was introduced as a part of the Extensible Firmware Interface (EFI) initiative. The GPT provides you with a more flexible mechanism for partitioning disks than the older Master Boot Record (MBR) partitioning scheme that has been common to PCs.
A partition is a contiguous space of storage on a physical or logical disk that functions as though it were a physically separate disk. Partitions are visible to the system firmware and the installed operating systems. The system firmware controls access to a partition before the system boots the operating system, and then the operating system controls this access after it starts.
GUID Partition Table (PDF) 
This document provides you with a step-by-step guide to install an operating system into GPT Disk on Intel Hardware RAID, under a uEFI environment.
Size: 4.0 MB
Date: April 2015
Revision: 1.1
Note: PDF files require Adobe Acrobat Reader*.