Extending a partition (volume) in the latest Windows Operating Systems is simple and straight forward when a computer meets the requirements. We discussed it and showed how to extend C drive on a Windows 10 computer. Recently I had to do the same volume extension on a Windows 2019 server but noticed that the extend volume greyed out in disk management. I’m sure my Windows server met the most of the requirements to extend a volume, but still why it is greyed out?
After digging all scenarios, I found out the reason why I was not able to extend the volume even though I have an empty space on the same disk next to the partition. By the way, this is a virtual machine on Azure cloud. Though it is a Windows 2019 server in this example, the below methods are applicable for Windows 2016/2012 R2 servers and client Operating Systems like Windows 10.
Basic Requirements to get ‘Extend Volume’ Option in Windows OS
Here are the few basic requirements to get the option to extend a volume/partition when you do not have enough space on a partition.
1) The disk should have unallocated space.
There should be unallocated space on the same disk where the partition you are going to extend. You can’t extend a volume across different drives. If the disk doesn’t have unallocated space, then you need to delete an existing partition next to it to get unallocated space.
2) The unallocated space should be on the precisely next (right side) of the partition that needs be extended.
If there is unallocated space somewhere on the same disk but not next to the partition at the right side, then the extend volume will be greyed out.
3) Only NTFS or no file system (RAW) supported
Though a partition is meeting the above 2 requirements, if it is formatted in FAT32 or other file system formats, then you will not get the option to extend the volume.
To find out more requirements, you can check this excellent guide written with screenshots and explanation.
Here is my example.
In my case, it is matching all 3 requirements. My server has unallocated space on the same disk, next to the partition (at right side) and the volume is formatted in NTFS.
In this example, the problem is with the size of the partition and file system type.
The partition size is 2TB (2048GB), and it is in MBR file system format. MBR (Master Boot Record) is an old type of disk format which works with the legacy BIOS and all Windows Operating Systems. The maximum partition size it can have is 2TB only. Even if you create a new partition with more than 2TB on MBR disk, it will detect the first 2TB only.
GPT is the other advanced version of disk format which support larger partition size. GPT has many advantages, but it can work with only the UEFI BIOS and latest Windows Operating Systems.
Since my disk is formatted in MBR style and the partition is already 2TB, I did not get the option to extend the volume even though there is unallocated space next to it.
How to find MBR or GPT?
To find out whether a disk is in MBR or GPT format, right-click on the disk in disk management, click Properties and go to Volume tab.
Here you will find out the style of partition.
In summary, the reason for extend volume greyed out is because of the MBR disk type with 2TB partition already. In MBR disk, we can’t extend a partition more than 2TB.
How to Extend a partition which is more than 2TB in MBR Disk?
The short answer is we can’t do it. It is the limitation of MBR disk.
The workaround would be to convert the disk from MBR to GPT if the existing Windows OS can work with GPT disks.
Convert MBR to GPT without data loss
Whatever method you are going to try, if the data on the disk is critical, please take a backup before proceeding any steps. Changing the disk formats, types and file system sometimes may lead to data loss.
There are few third-party disk management tools can convert a disk from MBR to GPT without data loss.
MBR to GPT without any tools
We can use the same Windows disk management tool to convert a disk. But it should not have any partitions in it. In this case, we need to take a backup of the content, then delete all partitions and convert the disk.
Technically, when we delete an existing partition, then there is no need of extending it. We can simply create a new partition with the required size. In future, since the disk is in the GPT file system, it can be easily extended beyond 2TB.
Also, you may not face this issue in the regular client, or physical servers since the physical disk may not go beyond 2TB. But in a data centre environment or virtualisation platforms such as Hyper-V or VMware and cloud-based solutions such as Microsoft Azure, you may have larger disks and partitions.
Next time if the extend volume is greyed out in a 2TB partition, check the disk style format whether it is in MBR or GPT.