By Cherry / Last Updated May 12, 2023

Why convert MBR to GPT in Windows Server 2008 (R2)?

MBR and GPT are two kinds of partition styles. MBR (the Master Boot Record), supported by the legacy BIOS, only allows you to create 4 primary partitions. To create more partitions, you can convert primary partition to logical partition. It only supports disk volume up to 2TB. If the disk is larger than 2TB, the extra space will not show in Windows Explorer and you can see it as unallocated space in Disk Management. GPT (the GUID partition table) requires that your motherboard supports EFI/UEFI. It allows you to create up to 128 primary partitions and supports larger disk size which is up to 9.4ZB.


For the advantages of GPT over MBR, you need to convert MBR disk to GPT in Windows Server 2008 (R2) sometimes.

For example, if your hard drive is 3TB or 4TB, but it only shows 2TB in File Explorer, you need to convert MBR to GPT. Or if you need more than 4 primary partitions on the hard drive, but the MBR does not allow you to create more primary partitions, you can convert MBR disk to GPT in Windows Server. Well, here is the question, how to convert MBR disk to GPT without data loss in Windows Server 2008 (R2)?

Windows 2008 cannot convert MBR to GPT disk

Windows Server 2008 Disk Management provides you with the feature "Convert to GPT Disk". However, when you try to use it to convert MBR to GPT in Windows Server 2008 (R2), you may find that the option Convert to GPT Disk greyed out.

greyed out

Actually, the Windows 2008 (R2) Disk Management can only convert an empty MBR disk to GPT, if MBR disk has partitions, the "Convert to GPT Disk" is gray by default. If you need to convert the MBR disk to GPT, you have to delete all partitions on the hard drive and then, it can be converted. Thus, the data on the hard drive would be deleted too.

Note: If you try using another Windows built-in utility – DiskPart- to convert MBR to GPT, you also need to delete all existing partitions on the target disk beforehand.

If you have partitions on the disk, to avoid data loss, you can back up the hard drive at first; then delete all partitions, use Disk Management to convert it to GPT and restore data. Or you can use certain third-party software to convert MBR to GPT without data loss in Windows Server 2008 (R2).

Convert MBR to GPT without data loss in Server 2008 (R2)

AOMEI Partition Assistant Server can be a great choice for converting disk into GPT without data loss. This MBR & GPT conversion tool allows you to convert system disk or data disk into GPT without deleting any partition on Windows Server 2008 (R2) and Windows Server 2003, 2012 (R2), 2016, 2019, 2022 and all Windows PC OSes. Here are the detailed steps of how to convert MBR to GPT without data loss in Windows Server 2008 (R2), 2012, 2016, 2019.

Download Demo Server 2008/2012/2016/2019/2022
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Please note before conversion:
Before you convert an MBR boot disk to GPT, make sure your motherboard supports EFI/UEFI. Otherwise, you cannot boot successfully after the conversion.
Windows 32bit system does not work on a GPT disk. Thus, if your system is 32bit, the operation is unable to continue. You need to upgrade your system to 64bit.
To avoid data loss caused by inappropriate operations, it is advised to backup important files.

Step 1. Install and run AOMEI Partition Assistant Server. Click the MBR disk that you need to convert to GPT and choose Convert to GPT Disk in the right pane.

Convert Data Disk To Gpt

Step 2. It will pop out a window to ask if you are sure to convert the selected disk from MBR to GPT, click OK to confirm.

Ok To Gpt Data Disk

Step 3. You will be sent back to the main interface and you’ll see the MBR disk has already changed into GPT partition type. Then, click Apply and Proceed to commit the operation.

Apply To Gpt Data Disk

If the system disk is involved, a reboot is necessary. After converting the system disk into GPT, you should change the boot mode to EFI/UEFI.
You are also allowed to convert GPT to MBR without data loss as well via AOMEI Partition Assistant Server.
To convert MBR to GPT, or convert GPT to MBR without operating system, you can first use the software to make a bootable media, from which you can boot your computer, and then convert disk in WinPE mode.


AOMEI Partition Assistant Server is a nice choice for MBR to GPT conversion without data loss in Windows Server 2008 (R2), 2012 (R2), 2016, 2019, 2022 and Windows 11/10/8/7. In fact, it is more than an MBR GPT disk converter. As a great disk partition manager, it also provides you with many other features for disk management like splitting partition, moving partition and copying partition, etc.

Apart from Server edition, you can also choose AOMEI Partition Assistant Unlimited for unlimited computers within one company at one location, and AOMEI Partition Assistant Technician for unlimited computers at multiple locations.