Solution - Cannot Extend Volume in Windows Server 2016

by James, Updated on: October 2, 2021

Partition size has been allocated after installing Operating System or by server manufacturer, but you need to reallocate the partitions after running the server for a period of time. The typical example is that C drive is getting full. To help solve this problem, Microsoft provides Extend Volume function in native Disk Management from Server 2008. Windows Server 2016 inherited the same function without any improvement. Many server administrators feedback that they cannot extend volume with Server 2016 Disk Management, because Extend Volume is greyed out. This article introduces the reasons why you are unable to extend volume in Windows Server 2016 Disk Management and the corresponding solutions.

1. Why cannot extend volume in Server 2016 after shrinking

A 500GB disk can't be increased to 1TB (except virtual disk), so before extending a partition, you must delete or shrink other one to get Unallocated space. Disk Management has Shrink Volume function to decrease partition size and make Unallocated space without losing data. Many people shrunk partition D (or E) successfully, but they found that they cannot extend volume C in Windows 2016 server.

Cannot extend volume

This is because:

  • Extend Volume function can only add Unallocated space to the left contiguous partition.
  • Shrink Volume can only make Unallocated space on the right.

As you see in the screenshot, after shrinking D: drive, I get 20GB Unallocated space on the right of D. This space is non-adjacent to C drive and is on the left of E, so Extend Volume is disabled to both partitions.

This is the most common reason why you can't extend volume in Server 2016 Disk Management. To solve this problem, if you want to extend system C drive, you need to move Unallocated space behind C drive in advance.

Solution when you cannot extend volume in Windows Server 2016 after shrinking:

  1. Download NIUBI Partition Editor, right click D: drive and select "Resize/Move Volume", drag the middle towards right in the pop-up window. Then Unallocated space will be moved next to C: drive.
  2. Right click C: drive and select "Resize/Move Volume" again, drag right border towards right to combine this Unallocated space.
  3. Click Apply on top left to execute.

NIUBI Partition Editor is designed to work in virtual mode, real disk partition won't be modified until you click Apply to confirm. If you did something wrong, simply click "Undo" to cancel. The pending operations marked as Check can be done without rebooting server.

Watch the video how to operate:

Video guide

2. Why cannot extend partition in Server 2016 after deleting

Because Disk Management is unable to extend partition C after shrinking D, some people tried to delete D instead, but Extend Volume is still disabled. There are 2 common reasons why you cannot extend partition in Windows Server 2016 Disk Management after deleting.

Extend Volume function only supports extending NTFS and RAW (no file system) partition, FAT32 and any other types of partition can't be extended even if there is adjacent Unallocated space on the right side.

Extend Volume disabled

The type of the partitions that you want to delete and extend are different. On MBR disk, Free space that deleted from a Logical drive can't be extended to any Primary partition. Unallocated space that deleted from Primary partition can't be extended to any Logical drives.

Extend Volume greyed out

Solution when you are unable to extend volume in Windows Server 2016 because of non-supported FAT32 partition or the restriction between Primary and Logical partition, simply drag and drop to resize partition with NIUBI Partition Editor. Follow the steps in the video:

Video guide

3. Why unable to extend volume past 2TB on MBR disk

Extend Volume grayed

To a server, it is very common to use 2TB to 4TB single disk or over 10TB RAID array. If you initialized a disk as MBR, you'll find that only 2TB disk space can be used, the remaining disk space is shown as Unallocated and can't be used.

As the screen shot shows, drive H is NTFS and there is contiguous Unallocated space on the right, but Server 2016 Disk Management can't extend this partition.

Solution when you can't extend partition past 2TB in Windows Server 2016: convert disk from MBR to GPT in advance, then you can extend partition with Unallocated space easily. Watch the video how to do this:

Video guide

In Summary

When you cannot extend partition in Windows Server 2016 Disk Management, find out the reason according to your own disk partition structure, then follow the corresponding solution above. Besides shrinking, moving and extending partitions, NIUBI Partition Editor helps you merge, copy, convert, defrag, wipe, hide partition, scan bad sectors and much more. It is much faster than other tools because of its advanced file-moving algorithm. The most important, it has unique 1-Second Rollback, Virtual Mode and Cancel-at-well technologies to protect your system and data.

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