Windows Server 2012 extend system volume

Updated on: November 16, 2019

This article introduces how to extend system partition on Windows Server 2012 R2 without data loss. 3 ways to enlarge system volume with detailed steps.

Extend system volume in Server 2012 DM

Many Windows 2012 servers have running for several years, there is a common issue in them that system partition C: is getting full. Nobody likes to waste a long time to recreate partitions, restore from backup and verify data. It can't be better if you can extend the system partition fast and without losing data.

To extend partition in Windows Server 2012, the native Disk Management tool is an option. However, because of many restrictions it is not the best choice.

To extend system partition with Server 2012 Disk Management, your disk partition configuration must meet the requirements: there must be adjacent Unallocated space behind system C drive.

Although there is advanced Shrink Volume and Extend Volume functions in Disk Management, you can't extend system partition by shrinking other data volumes.

After shrinking the contiguous partition (D:), you'll find that Extend Volume greyed out for system C: and other data drive E.


  • Shrink Volume function can only decrease a drive towards left and make Unallocated space on the right side.
  • Extend Volume can only combine Unallocated space to the left adjacent partition.

Delete D: drive, there will be adjacent Unallocated space, then Extend Volume is enabled.

Extend volume disabled

Do NOT delete D if you installed programs or there are Windows services running from it.

If partition D is Logical, you still cannot extend system volume in Server 2012 Disk Management after deleting it.

  • Because, Unallocated space deleted from a Primary partition can't be extended to any Logical drives.
  • Free space deleted from a Logical partition can't be extended to any Primary partitions.

This is another inherent restriction in MBR style disk.

After deleting any Logical partition, the disk space will be shown as Free. To convert it to Unallocated space, you have to delete all other Logical partitions and then the entire Extended partition.

Cannot extend

Extend system partition by shrinking D or E

Comparing with Server 2012 Disk Management, NIUBI Partition Editor has many advantages such as:

After shrinking and extending disk partition with NIUBI, Operating System, programs and associated setting, as well as anything else keep the same with before. There is no other operation needed even if you use any types of hardware RAID arrays, or VMware/Hyper-V.

Download NIUBI Partition Editor and you'll see all disk partitions with structure and other information. There is C, D, E and system reserved partition in Disk 0. Original C: drive is 40GB and D: is 70GB.

NPE Server

Steps to extend system partition drive in Windows Server 2012:

Step 1: Right click drive D: and select "Resize/Move Volume", drag left border towards right in the pop-up window. (or enter an amount manually)

Shrink D

Then part of unused space is converted to Unallocated on the left side of D.

Drive D shrank

Step 2: Right click system partition C: and select "Resize/Move Volume" again, drag right border towards right to combine Unallocated space.

Extend C drive

Then system volume C is extended from 40GB to 60GB.

C drive extended

NIUBI is designed to work in its virtual mode, the operations you do will be listed as pending on bottom left. So, member to click Apply on top left to take effect to real disk partitions.

If you want to get unused space from non-adjacent partition (E:), there is an additional step to move Unallocated space. Watch the video how to extend system volume in Windows 2012 server by shrinking other volumes:

Video guide

Enlarge system partition with other disk

In few servers, there are no other volumes in the same disk, or not enough unused space in other partitions. In that case, NO software can enlarge system partition by adding space from other separated disk. The "separated" disk means Disk 0 or 1 that shown by NIUBI, no matter the disk is physical or RAID array.

However, there is still a way to increase system partition size by copying to a larger disk. Follow the steps in the video:

Video guide

Copying single C: drive cannot ensure Windows bootable. After clone complete, replace the small disk or change BIOS to boot from the large disk.

Comparing with other software, NIUBI Partition Editor has powerful 1 Second Rollback, Virtual Mode, Cancel-at-will technologies to protect system and data. It is also much faster because of its unique file-moving algorithm.