By Teresa / Last Updated August 19, 2019

MBR or GPT Windows Server

When first install a disk to machine, you’ll find it is marked as “unknown” in Windows Server Disk Management. You need to initialize it MBR or GPT type. Well, which one is better for your Server? You can tell that after a basic understanding of MBR and GPT.

MBR, short for Master Boot Record, is an old and common-used disk layout. The GPT, GUID Partition Table, provides a more flexible principle for partitioning a hard disk. GPT has visible advantages compared to MBR. In detail, it supports disk size more than 2TB; support unlimited number of partitions; has no limitation to the size of partitions; and every partition on GPT disk can have a same partition. All merits account for that why so many users want to convert MBR to GPT on Windows Server.

Important: since GPT is super than MBR, there is limit for converting to GPT on Server. That is, the computer should support to boot from UEFI/EFI if plan to convert MBR-formatted system disk to GPT. Besides, 32bit system does not work on a GPT disk. So, upgrade system to 64bit before converting. On the contrary, if you don’t convert GPT to MBP disk on Server which cannot support GPT disk, you will be unable to access data.

What does Windows Server Manager can do in MBR & GPT conversion?

Windows Server offers Server Manager to assist you convert MBR/GPT in graphical user-interface. Disk Management allows you to convert an EMPTY disk to GPT in seconds, so does Diskpart in CMD. If there is partition or volume on the disk, when right-click the disk in Disk Management, you’ll find Convert to GPT Disk grayed out and you have option to convert it to Dynamic Disk.

How to keep data on the disk intact during MBR and GPT converting on Server? Fortunately, Server Manager also provides Windows Server Backup that can help you back everything up before deleting. Learn the detailed steps below.

Convert MBR to GPT without data loss via Windows Server Manager

Following will take convert MBR-formatted data disk to GPT on Windows Server 2008 for example since you cannot delete system partition under Windows Server environment. Converting data disk to GPT mostly is to make full use of disk capacity, for example, when 4TB HDD not working on Windows Server.

1. Backup disk volume via Windows Server Backup

You can backup volume to local disk or removable device. If back up to removable device like USB flash drive or external hard drive, connect it to your Server in advance.

Step 1: open Server Manager and go Storage > Windows Server Backup (you can access to this utility by typing “windows server backup” in the search box). If did not use this feature before, you need to install (Server Manger\Features) it first.

Step 2: in the right pane, click on “Backup Once Wizard”. Follow the wizard to complete backup settings.

Backup Once Wizard

Step 3: after the backup process completes, go to Disk Management and delete existing partitions or volumes.

Delete Volume

2. Convert MBR to GPT on Windows Server 2008 (R2)

Step 1: in Disk Management, right-click the disk and select “Convert to GPT Disk”.

Convert to GPT Disk Disk Management

Step 2: in a few seconds, the convert process will be completed. You can check that by right-clicking the disk again, and you’ll find the feature changes to “Convert to MBR Disk”. That is to say, you can convert empty disk to MBR with Disk Management as well.

Step 3: right click the unallocated space to create a new partition with “New Simple Volume”, so that you can recover backed up data.

Create Volume

3. Recover backup image via Windows Server Backup

At the main interface, you can find the backup you just created displayed. Click “Recover Wizard” this time. Follow the wizard to complete file recovery.

Recovery Wizard

As covered before, above method is not applied to converting system disk between MBR and GPT because you cannot delete C drive in Windows environment. If you have Server installation disc or Windows Recovery Environment around, you can make a backup for your Server system disk and recover it back after converting to GPT. This process requires you to convert disk to GPT using Diskpart in Command Prompt. Syntax would be:

list disk>select disk n>clean>convert gpt

Diskpart Convert GPT

It would work yet also takes up a lot of time and effort at the same time. Therefore, it is a good idea to rely on professional conversion tool: AOMEI Partition Assistant Server. It allows you to convert between MBR and GPT on Windows Server without deleting or formatting volumes and partitions on system disk and data disk, let alone data loss. This software simplifies the converting process to the most. Its user-friendly interface is also suitable for both computer novice and experts.

How to convert MBR GPT Server 2008 (R2) without deleting?

Next part will take convert MBR-formatted system disk to GPT partition table on Server 2008.

Convert MBR to GPT Windows Server 2008 without losing data

Step 1: run AOMEI Partition Assistant and right click the disk you want to convert, select “Convert to GPT Disk”.

Convert System Disk to GPT

Step 2: it will prompt two dialogs to let you confirm the conversion.

OK to GPT System Disk

Step 3: click “Apply” to execute the pending operation.

Apply to GPT System Disk


  • A reboot is required when system drive is involved in.

  • To boot from GPT disk, you need to change Legacy to UEFI.

Change GPT back to MBR on Server with ease

If you want to convert GPT to MBR disk on Windows Server in the future, you can use the same feature in the same software. When right click on GPT disk, you’ll find the function name changed to “Convert to MBR Disk”. The rest is the same as above operation.

Convert Data Disk to MBR

Tips: After converting to MBR, you need to change UEFI/EFI to Legacy if the selected disk is system disk.


AOMEI Partition Assistant Server is reliable and powerful partition tool that created for Windows Server OS in particular. So it is also can be used to convert MBR GPT in Windows Server 2012/2003 (R2)/2016 without data loss.