Extend Volume disabled/greyed out in Windows Server 2016
Windows Server 2016 native Disk Management has Shrink Volume and Extend Volume functionalities to change size of allocated partition without losing data. However, many people feedback that Extend Volume is greyed out when extending a disk partition. The typical example is that Extend Volume is disabled for C drive after shrinking partition D. In this article, I’ll explain why Extend Volume grayed out in Server 2016 Disk Management and what to do when Extend Volume is disabled for C, D or other drive.
Why Extend Volume grayed out
In GPT hard disk, there are 2 common reasons why Extend Volume is unavailable. In MBR style hard disk, there is 1 additional reason. I’ll explain one by one.
No adjacent Unallocated space
A 256GB hard disk cannot be increased to 512GB by itself, so before extending a partition, you must shrink or delete another one to get Unallocated space. By deleting a drive, all disk space will be converted to Unallocated, but the files will be lost. By shrinking a drive, part of the unused space will be converted to Unallocated and you won’t lose files.
From Microsoft explanation, Extend Volume functionality only works when there is adjacent Unallocated space on the right side.
So, if you right click C drive directly without shrinking or deleting, of course Extend Volume is grayed out in Server 2016 Disk Management.
The most common scenario is that Extend Volume is disabled for C drive after shrinking D.
When your shrink partition D with Shrink Volume functionality, Unallocated space can only be produced on the right side of D. So, Extend Volume is greyed out for C drive except that you can move the Unallocated space to the left side with server partition software.
Not supported partition
In fact, both Shrink and Extend Volume only support NTFS partition, another common FAT32 partition is not supported.
To show you the truth, I formatted original drive D to FAT32. As you see, Extend Volume is disabled for D drive even though there is adjacent 20GB Unallocated space on the right side.
Restriction in MBR disk
This issue is common in MBR disk only, so you may ignore this reason if you are running GPT disk. (Luckily, hard disk will be formatted as GPT by default when installing Windows Server 2016.)
My hard disk is formatted as GPT, too, so I have to show you the truth with another computer running Server 2012.
I deleted the adjacent drive E, but Extend Volume is still disabled for partition D, why?
In GPT disk, you can create many partitions and all of them are Primary only. But in MBR disk, you can only create 4 partitions if they are all Primary, because there are only 4 entries in Master Boot Record. (From the entries Operating System can locate the position of each partition.)
To create more that 4 partitions, one of the entry must be assigned to the Extended partition. That is to say, 3 Primary partition plus an Extended partition. Extended partition works like a container and you can create many Logical partitions in it. Unlike Primary partition whose disk space will be converted to Unallocated after deleting, Logical partition will be converted to Free space after deleting. Free space is still a part in the container (Extended Partition), so it cannot be combined to other Primary partition.
Likewise, you cannot extend a Logical partition by deleting the adjacent Primary partition.
What to do when Extend Volume is disabled for C drive
Actually, it is very easy to solve this problem with disk partition software such as NIUBI Partition Editor. If you have shrank drive D and got Unallocated space on the right side, you can move Unallocated space to the other side with NIUBI, and then Extend Volume is enabled for C drive.
Download NIUBI Partition Editor Server, right click partition D and select “Resize/Move Volume”.
Drag the middle position towards the right side in the pop-up window.
Click OK, Unallocated space is moved to the left side of D.
Right click C drive and select “Resize/Move Volume” again, drag the right border towards right side in the pop-up window.
Click OK, Unallocated space is combined to C drive.
- The operations you do will be listed as pending on bottom left, real disk partition won’t be changed until you click Apply button on top left to confirm.
- The pending operations marked as
will be done in Windows, the ones marked as 
requires rebooting. - If there is Unallocated space adjacent to a FAT32 partition but Extend Volume is greyed out, simply follow Step 2 to combine the Unallocated space with “Resize/Move Volume” feature.
Video guide
In Summary
Shrink Volume of Disk Management can only produce Unallocated space on the right side, it causes Extend Volume disabled for C drive after shrinking D. In addition, both Shrink and Extend Volume functionalities support NTFS partition only. To fix Extend Volume greyed out issue in Windows Server 2016, you just need to run NIUBI Partition Editor to move the Unallocated space to behind C drive and then combine with “Resize/Move Volume” feature.
