If you need to convert MBR and GPT in Windows Server 2025, 2022, 2019, 2016, 2012 (R2), here you can find 3 methods to get it completed. But to convert MBR/GPT in Server without losing data, the AOMEI Partition Assistant can help you a lot.
When you first install a disk to a machine, you’ll find it is marked as “unknown” in the Windows Server Disk Management. In order to use the disk, you will need to initialize it as either an MBR or GPT drive. You may find yourself asking, which one is better for your Windows Server? You should be able to decide which one is better after reading a basic understanding of MBR and GPT.
MBR, short for Master Boot Record, is an old and commonly used disk structure. GPT, short for GUID Partition Table, is a modern disk structure that provides a much more flexible approach for partitioning hard disks. GPT, being a modern standard, has many advantages when compared to MBR. GPT is able to support disks larger than 2TB in size, has a theoretically unlimited number of primary partitions, and has no limitations on the size of partitions. These are the reasons that most users will choose to convert MBR to GPT on Windows Server operating systems like Server 2025, 2022, 2019, 2016, 2012, etc.
Important: Whilst we can consider GPT to be superior to MBR, there are some considerations before converting MBR to GPT on a Windows Server. The computer must boot from UEFI/EFI if you plan to convert an MBR-formatted system to GPT. Besides, a 32bit system will not work with a GPT disk, the system must be upgraded to 64-bit before the conversion. If you choose to use a GPT disk on a Server that cannot support it, you will not be able to access any of the data.
Windows Server offers a built-in Disk Management, which can assist you in converting between MBR/GPT through its graphical user interface. However, it is only able to convert an EMPTY disk to GPT or MBR in seconds as does Diskpart in command prompt, another snap-in tool in Server. If there is a partition or volume already on the disk, when you right-click on the disk in Disk Management, you’ll find Convert to GPT Disk grayed out.
So, here comes the question: how to convert MBR and GPT in Windows Server without data loss (deleting partitions)? Fortunately, Server Manager provides Windows Server Backup which can help you back everything up before deleting partitions. You can follow the detailed steps below.
The below shows how to convert an MBR-formatted data disk to GPT on Windows Server 2008 as you cannot delete the system partition under the Windows Server environment. Users typically convert their data disks to GPT in order to take full advantage of the disk’s capacity (due to the 2TB limit for MBR). An example would be when a 4TB HDD doesn’t work on a Windows Server.
You can backup the volume to the local disk or a removable device. If you back up to removable device like your USB flash drive or external hard drive, you should connect it to your Server in advance.
1.1. Open Server Manager and go Storage -> Windows Server Backup (you can access this utility by typing ‘windows server backup’ in the search box). If you haven’t used this feature before, you will need to install (Server Manager\Features) it first.
1.2. In the right pane, click on ‘Backup Once Wizard’. Follow the wizard to complete backup settings.
1.3. After the backup process completes, go to Disk Management, and delete the existing partitions or volumes.
2.1. In Disk Management, right-click the disk and select Convert to GPT Disk.
2.2. The conversion process will be completed after a few seconds. You can check the status by right clicking on the disk again, you should find that the option has changed to ‘Convert to MBR Disk’ from ‘Convert to GPT Disk’.
2.3. Right-click the unallocated space to create a new partition with the ‘New Simple Volume’ option, so that you can recover the backed-up data.
The backup that you just created is displayed in the main window. In order to recover – Click on ‘Recover Wizard’ and follow the steps in the window to complete the file recovery.
As we mentioned before, the above method can’t be applied to converting a system disk between MBR and GPT as you will be unable to delete the “C drive” within the Windows. If you have the Server installation disc or access to the Windows Recovery System you will be able to make a backup of the Server system disk and recover it after converting to GPT.
This process requires you to boot computer from the installation disc, press "Shift+F10" in the Windows Setup screen to launch the Command Prompt window, then execute the commands: list disk -> select disk n -> clean -> convert gpt.
Whilst the above method does work, it takes a considerable amount of time and effort. Therefore, we would always recommend using a professional conversion tool (AOMEI Partition Assistant Server Edition). It will allow you to convert both system and data disk to MBR / GPT on Windows Servers without deleting volumes. This software simplifies the process with its user-friendly interface suitable for both computer novices and computer experts.
The next part will show you how to convert an MBR-formatted system disk to a GPT partition table without removing any volumes on Windows Server 2012, 2016 , 2019, 2022, and 2025. But in order to avoid data loss caused by unexpected issues like power failure, it is always advised to back up system beforehand.
PS.: There is a Demo Version for free download and free trial.
Step 1. Run AOMEI Partition Assistant Server Edition, right-click the disk you want to convert, and select “Convert to GPT”. (As you can see, there are partitions on the OS disk)
Step 2. Two windows will appear asking you to confirm the conversion.
Step 3. Click “Apply” to execute the pending operation.
Tips: ①A reboot is required when the system drive is converted. ②To boot from a GPT disk, you will need to change Legacy to UEFI. ③If you cannot boot into Windows Server to convert MBR/GPT, you can first use this software to create a bootable media, boot Server from it and convert MBR to GPT in Win-PE mode.
If you want to convert a GPT disk to an MBR disk on Windows Server in the future, you can use the same function in AOMEI Partition Assistant Server Edition. When you right click on a GPT disk, you’ll find the function has changed to “Convert to MBR”. The rest of the steps is the same as above to complete the conversion.
Tip: After converting to MBR you need to change UEFI/EFI to Legacy if the disk you converted was the system disk.
AOMEI Partition Assistant Server Edition is a reliable and powerful partition tool that was created with Windows Server OS’ in mind. Naturally, it can also be used to convert between MBR/GPT in Windows Server 2012, 2016, 2019, 2022, and 2025 without any data loss. In addition, it is also able to move Windows Server to new hard drive, clone MBR disk to GPT, GPT disk to MBR, convert dynamic disk to basic without losing data, etc.