MBR or GPT for RAID
Redundant array of independent disks (RAID) is a data storage technology to improve
performance and reliability by combining many disks as one utilizing striping,
mirroring, or parity. There are different RAID levels, such as RAID 1, RAID 5, RAID
10, etc. People can choose different types of RAID based on their needs. Since the
RAID will be read or written as one single disk, you need to choose the partition
style for it. Among the differences
between MBR and GPT, the thing that matters most is the operating system
(OS) on your machine. MBR disk supports all versions of Windows, but GPT supports
only Windows XP 64 bit and later versions of Windows or the corresponding Windows
Server, only 64 bit of which support booting system from a GPT disk using Unified
Extensible Firmware Interface (UEFI) mode. Introduced for many years, UEFI is
supported in many computers. If your system and machine supports GPT disks, it is
recommended to convert RAID to GPT disk, because a basic MBR disk does not support
disk space more than 2TB, nor 4 primary partitions, while a GPT disk allows you to
manage disks of more than 2TB capacity and have as many primary partitions as you
like.
Convert disk to GPT with Disk Management
The Windows built-in utility Disk Management allows you to convert an empty MBR disk
to GPT, so you have to remove all the partitions on the disk before the conversion.
You can backup
the RIAD disk with third-party backup software or Windows Backup Utility. To
open Disk Management, you can go to Control Panel\System and Security, select Create
and format disk partitions under the Administrative tab. After the interface of Disk
Management show up, right click on a partition of the disk to be converted and
select Delete Volume. Use this method to delete the rest partitions on this disk
till it is shown as unallocated.

Right-click on this disk and choose “Convert to GPT disk”. The program will start to
convert RAID hard drive to GPT disk, which will take a little time.

If you cannot delete some partitions on the disk, you can try to delete partition using DiskPartfrom the command prompt. However, both tools, Disk Management and Diskpart, requires
to completely remove all the data on the disk. Is there a way to convert RAID to GPT
without losing data?
Convert MBR to GPT without data loss
AOMEI Partition Assistant Standard is a freeware that has multiple functions
regarding partition management. The feature Convert to GPT Disk can help you to
convert a disk with data to GPT or MBR partition style while the data remain intact.
For the disk to boot normally after the conversion, the system reserved partition
will become an MSR partition and EFI system partition, also known as ESP drive.
To convert RAID disk to GPT without data loss:
1. Download, install and open AOMEI Partition Assistant. Right-click on the RAID disk to be converted and select Convert to GPT disk.

2. Click OK to confirm the operation.

3. Click Apply, and then you will be prompted to click Next to continue.

The program will convert RAID to GPT in no time after you confirm the operation. If
it is a system boot disk that you want to convert, you need to upgrade to the Professional Edition of AOMEI
Partition Assistant. For Windows Server users, you can use AOMEI Partition
Assistant Server Edition, which supports Windows Server 2008/2008
R2/2012/2012 R2 as well as the corresponding Windows PCs.