Windows Server 2019: Convert MBR to GPT without Data Loss

Is MBR or GPT better for Windows Server 2019?

MBR and GPT are two different partition styles for disk configuration. MBR stands for Master Boot Record, using the standard BIOS boot mode. GPT is the abbreviation of GUID Partition Table, using the Unified Extensible Firmware Interface (UEFI) boot mode. The obvious benefits of using GPT disks include that you will be able to :

◗ Make the fullest use of a large hard disk that is over 2TB. GPT supports disks larger than 2 TB in size while MBR cannot.

◗ In contrast to the MBR disk partitioning style, which supports volumes up to 2 terabytes in size and up to 4 primary partitions per disk (or three primary partitions, one extended partition, and unlimited logical drives), the GPT disk partitioning style supports volumes up to 18 exabytes in size and up to 128 partitions per disk.

◗ GPT partition scheme allows users to enjoy UEFI boot mode that offers secure boot and prevents boot-time viruses from loading.

So, when building Server 2025/2022/2019/2016/2012 or Windows 11/10/8/7, a large number of users would like to choose the GPT disk style instead of MBR. If the default partition style is MBR, you can convert the basic disk from MBR to GPT in Server 2019 or other operating systems.

3 Methods to convert MBR to GPT in Server 2025/2022/2019/2016/2012

Now, we will discuss how to convert MBR to GPT in Windows Server 2019. Three different methods are recommended. Check them out one by one and choose a proper one based on your requirements and situation.

✎Note: Before you convert a disk, backup partition or data on it and close any programs that are accessing the disk.

1. Convert MBR to GPT via Server 2019 Disk Management (Data Loss)

First of all, you can use GUI Server inbuilt Disk Management, which can convert an empty disk from MBR to GPT or GPT to MBR. So, you have to delete all existing partitions on the MBR disk before conversion.

Step 1. Press “Windows+R” to open “Run”, type “diskmgmt.msc” in the box and press Enter.

Step 2. If the disk contains any partitions or volumes, right-click each and then click “Delete Volume”.

Step 3. Right-click the MBR disk that you want to change into a GPT disk, and then click “Convert to GPT Disk”.

Step 4. Follow the instruction to finish the conversion.

✎Note: This method is only proper for converting data disk between MBR and GPT in Windows Server 2019/2016/2012/2008. You cannot use it to convert the system disk because you are not allowed to delete the system partition within Windows Server.

2. Change MBR disk to GPT using Command Line (Data Loss)

Compared with Disk Management, Command Line can convert data disk and system disk as long as it does not contain any partitions. To convert non-system disks, you can perform it within Windows Server.

Step 1. Press “Windows+R” to open “Run”, type “cmd” in the box and press Enter.

Step 2. In the pop-out Command Prompt Window, type “diskpart” and press “Enter”.

Step 3. When diskpart.exe is launched, input the following commands in turn:

• list disk

• select disk # (# is the target disk number)

• clean

✎Note: Running the clean command will delete all partitions or volumes on the disk. If the MBR disk has no partitions, this command can be neglected.

• convert gpt

To convert Server 2019 system disk to GPT, you need to do as below with using the Server 2019 setup CD:

Step 1. Boot computer from the Server 20019 setup/installation CD. Or you can burn the Server 2019 to USB to create a bootable USB stick.

Step 2. On the first screen, select installation language, Time and keyboard layout the click “Next“.

Step 3. In the next window, click “Repair your computer”.

Step 4. Press the "Shift + F10" keys together on the keyboard. This will open the command prompt window:

Step 5. Then execute the commands as above (list disk->select disk->clean->convert gpt).

After converting the system disk within the WinPE environment, you need to reinstall Windows Server 2019 from scratch.

3. Convert MBR to GPT with Server partition manager (without data loss)

Briefly, the first method can convert an empty non-system disk to GPT and the second method is able to convert the blank system and non-system hard disks to GPT. But it requires you to reinstall OS and other programs from scratch afterward. So, is there any way to convert the boot disk and data disk without deleting existing partitions?

There is such a way to convert MBR to GPT in Windows Server 2019 without data loss. That is to resort to a third-party Server Partition Manager like AOMEI Partition Assistant Server. This software can convert both the boot disk and data disk between MBR and GPT partition styles without deleting volumes. So, all the contents on the disk will be safe. Now you can download its demo version for a free trial and refer to the following tutorial to learn how to convert the system disk when the Server is running.

✎Note: To avoid data loss caused by improper operation or sudden power failure, it is always advised to back up system in advance.

Step 1. Install and run AOMEI Partition Assistant Server. Right-click the disk you want to convert and choose “Convert to GPT”.

Step 2. In the pop-out window, click “OK” to confirm this operation.

Step 3. Back to the main interface, click “Apply” to commit the pending operation.

If you need to convert MBR to GPT in Windows Server 2019 without loading the operating system, you can first create a bootable media (USB stick).

Step 1. Plug an empty USB drive into a working Server computer. Install and run AOMEI Partition Assistant Server on that computer as well. Click “Tools” in the top toolbar, and choose “Make Bootable Media”.

Step 2. Choose the inserted USB drive and click “Proceed”.

Step 3. Wait for the process to be done.

Then plug the bootable USB drive into the Windows Server 2019 computer that contains the disk you want to convert into GPT. Reboot it and enter BIOS environment to change the boot order to boot computer from the destination USB stick. At last, do as above to convert disk from MBR to GPT or GPT to MBR without loading OS.

Conclusion

After reading this post carefully, you will be clear about how to convert MBR to GPT in Windows Server 2019 through three different methods. AOMEI Partition Assistant Server is compatible with all editions of Windows Server and Windows PC. So, this method can be used to convert MBR to GPT in all Servers and Windows PC.

Apart from converting disk partition styles without losing data, this tool also has many other amazing functions such as migrating OS to SSD/HDD, extending partition, converting primary drive to logical or logical to primary drive without data loss, moving installed apps, changing hard drive serial number without losing data, etc.

What's more, for advanced users, there is an the Unlimited Edition for you if you want unlimited usage within one company or a team. The "Create Portable Version" function enables users to create AOMEI Partition Assistant on a removable device so that users can directly run it on target computers without installation.