Cannot extend volume in Windows Server 2012 R2

by Lance, Updated on: July 5, 2022

This article introduces why cannot extend volume in Windows Server 2012 R2 Disk Management or with Diskpart command, and how to fix this issue easily.

1. Why cannot extend volume with Server 2012 Diskpart cmd

Many server administrators like to use command line tool. To extend partition in Windows Server 2012, Diskpart is one of the options, which is native tool integrated from Windows XP. However, it only works under restricted condition. Many people receive error while extending partition with this native tool such as:

Press Windows + R keys together on the keyboard, input diskpart and press Enter, type help extend in command prompt and press Enter again, then you'll see the reasons why Diskpart cannot extend volume in Server 2012 (R2).

Diskpart restrictions

To be short:

In other words, Diskpart can only extend NTFS partition by deleting its adjacent volume on the right.

2. Why cannot extend partition in Server 2012 Disk Management

The same with Diskpart, Server 2012 Disk Management can't extend a partition by shrinking another one, FAT32 partition also can't be shrunk or extended.

Because, Unallocated space can only be made on the right while shrinking a partition (such as D:). Neither Diskpart Extend command nor Disk Management Extend Volume function can extend Unallocated space to the nonadjacent C: drive or the right partition E.

As the screenshot shows, Extend Volume greyed out for C and E drive after shrinking D.

Extend volume disabled

There is two additional reasons why Disk Management cannot extend partition in Windows 2012 server on MBR disk.

Cannot extend

Unallocated space that deleted from a Primary partition can't be extended to any Logical drive, Free space  that deleted from a Logical drive can't be extended to any Primary partition.

On MBR disk, there are maximum 4 entries in master boot record sector, so you can create maximum 4 Primary partitions, or 3 Primary plus an Extended partition. More partitions can only be created as Logical in the Extended partition.

As you see in the screenshot, disk space of Logical drive D is converted to Free after deleting. This Free space is still part of the Extended partition. When right clicking C drive, Extend Volume is still disabled.

You cannot extend partition past 2TB in Windows Server 2012 with Disk Management.

As you see in my test server, F: drive is NTFS and there's contiguous Unallocated space on the right, but Extend Volume is disabled, too.

This is because, the maximum partition size on MBR disk is 2TB. If you initialized a 4TB disk as MBR, only 2TB space can be used. The remaining 2TB space shows as Unallocated, it can't be used to create new volume or expand another one with Disk Management.

Extend Volume disabled

3. What to do if unable to extend volume in Windows Server 2012

In most cases, the reason why cannot extend volume in Server 2012 Disk Management is because that Unallocated space is non-adjacent. To fix this issue, you need to move partition D to the right and make Unallocated space contiguous to C drive.

What to do if you cannot extend volume C in Windows Server 2012 r2 after shrinking D or E:

Step 1: Download NIUBI Partition Editor, right click the contiguous partition D (E: in some servers) and select "Resize/Move Volume", drag the middle  of this partition towards right in the pop-up window:

Move rightwards

Then Unallocated space is moved to the left side.

Move Unallocated space

Step 2: Right click C: drive and select "Resize/Move Volume" again, drag right border towards right in the pop-up window.

Expand C drive

Then Unallocated space is merged into C: drive.

Unallocated add to C

Step 3: Click Apply on top left to take effect.

If you already shrunk D drive and cannot extend volume E with Server 2012 Disk Management , or if you cannot extend FAT32 partition, follow the steps in the video to resize partition with NIUBI:

Video guide

If you cannot extend partition past 2TB in Windows Server 2012 Disk Management, follow the steps in the video to convert MBR disk to GPT and then extend partition with Unallocated space:

Video guide

Besides help fix the issue that can't extend volume in Windows Server 2012/2016/2019/2022/2008/2003, NIUBI Partition Editor helps you merge, copy, convert, defrag, wipe, hide, scan partition and much more. Better than other tools, it has unique 1-Second Rollback, Virtual Mode and Cancel-at-will technologies to protect your system and data.