Windows 2008 server has kept running for many years, the storage devices need to be replaced or upgraded with larger disks. The most common issue after upgrading disk is that you cannot use full disk space. For example, on a 4TB disk you can only use 2TB, the remaining space can't be used to create new volume or extend to other one in Disk Management. In that case, you need to convert MBR disk to GPT. On MBR disk, you can create maximum 4 Primary partitions, if you want to create more, you also need to change disk from MBR to GPT. This article introduces how to convert MBR to GPT in Windows Server 2008 (R2) without data loss.
1. Convert MBR to GPT in Server 2008 R2 Disk Management
Windows Server 2008 native Disk Management has the option to convert disk between MBR and GPT, but you must delete all partitions on this disk in advance, otherwise these options are grayed out. As you see in my test server, there are drive F: and H: on Disk 1.
Obviously, it is not a good idea to delete all partitions on a disk. You cannot convert system disk from MBR to GPT in Server 2008 Disk Management, because partition C with operating system can't be deleted. There are better methods to convert MBR to GPT in Windows 2008 server without losing data. The methods to convert system disk and non-system disk are different, follow corresponding method below.
2. 1-click method to change MBR to GPT for non-system disk
If you want to convert MBR disk to GPT without Operating System, it is very easy and fast with NIUBI Partition Editor.
Download this program and you'll see all disk partitions with structure and other information on the right.
How to convert MBR to GPT in Windows Server 2008 R2 with NIUBI:
Watch the video how to convert disk from MBR to GPT in Windows Server 2008 R2:
3. Convert system disk with MBR2GPT.exe in Server 2008 (r2)
It is a bit complicated while converting MBR disk to GPT with operating system. Besides keeping all files intact, the server must boot successfully. Any slight error leads to system damage or boot failure. There are some third party software that claim to be able to convert system disk from MBR to GPT, but it is always suggested to convert with MBR2GPT.exe, which is provided by Microsoft.
MBR2GPT works via command prompt, it is a native tool from Windows 10 and Server 2019. Windows Server 2008 (and R2) has no such tool, you need to download Windows Server 2019/2022 ISO from Microsoft and create a bootable DVD or USB flash drive. If you run Windows 2008 as guest server in VMware/Hyper-V, you just need to select this ISO file and boot from it.
① Precondition to run mbr2gpt.exe in Server 2008 (R2)
It is easy to convert MBR to GPT in Windows Server 2008 with MBR2GPT command tool, but your disk partition configuration must meets the requirements below:
- There are maximum 3 Primary partitions on the system disk.
- One of the partitions is set as active and is the system partition.
- There's no Logical drive on the system disk.
- All partitions on the disk must be recognized by Windows, that means, there's no EXT2/EXT3 or other types of partition for Linux/Mac.
If any of these checks fails, the conversion will not proceed and an error will be returned, so don't worry about system and data safety.
Some people receive error when converting system disk - "Validating layout, disk sector size is: 512 bytes Disk layout validating failed for disk 0", "MBR2GPT: Conversion failed". This is common error because partition layout check fail. If your disk partition configuration doesn't meet the requirements, follow the methods below to make modification.
② Modify partition type and layout if needed
Press Windows and R together on the keyboard, type diskmgmt.msc and press Enter. Then you'll see disk with partition layout and other information in Server 2008 Disk Management. Check the disk partition layout if it needs to be changed.
❶ Convert partition type:
From this screenshot, drive D: is Logical partition. In this situation, you need to convert D to Primary partition with NIUBI.
Note: all partitions should be Primary before converting with MBR2GPT command.
❷ Move partition to another disk:
From this screenshot, there are 4 Primary partitions on Disk 0. In this situation, you need to move partition to another disk with NIUBI.
Note: there could be maximum 3 Primary partitions on the MBRdisk.
③ Steps to convert MBR to GPT in Windows Server 2008 R2 with mbr2gpt cmd
Step 1: Download Windows Server 2019 ISO and create bootable DVD or USB flash drive.
To VMware/Hyper-V virtual server, you just need to select this ISO file and boot from it.
Step 2: Restart server and boot from the bootable DVD or USB flash drive, when it ask you to "Install now", do not click it, click "Repair your computer" on bottom left. Then click Troubleshoot > Command Prompt in next windows.
Step 3: You just need to input 2 commands to convert MBR system disk to GPT:
- Type cd.. and press Enter.
- Type mbr2gpt /convert and press Enter.
Watch the video how to convert MBR disk to GPT in Windows Server 2008 (r2) with MBR2GPT command:
It requires more steps to convert system MBR disk to GPT in Server 2008 with MBR2GPT command, but it's safer than other tools. If the disk has no Operating System, MBR2GPT command doesn't work, but it is very easy to convert MBR to GPT in Server 2008 R2 with NIUBI Partition Editor. Besides converting MBR to GPT, this tool helps you convert partition NTFS to FAT32, convert between Primary and Logical. It also helps you copy, shrink, extend, merge, move, defrag, wipe, hide partition, optimize file system and much more.