Cannot extend C drive in Windows Server 2012 (R2) Disk Management

From Windows Server 2008, Microsoft provides GUI function in Disk Management to change partition size. It is great improvement to previous editions. With Shrink Volume function, you can decrease an existing partition without reboot. Extend Volume helps you easily increase a partition size. However, many people try to shrink D drive, but found they cannot extend C drive, because Extend Volume is greyed out. In this page, I’ll tell why you cannot extend C drive in Windows Server 2012 (R2) Disk Management, and how to solve this problem in an easy way.

Scenarios of cannot extend C drive

The reason why so many people encountered this problem is because Extend Volume function disabled in most cases. Here I’ll show one by one.

Right-click Windows and click Disk Management.

1. Right click C drive directly, Extend Volume is grayed out.

Cannot extend C

2. Shrink the adjacent drive D and retry.

Shrink drive D

Shrink 10GB space.

Shrink drive D

Right click C drive, Extend Volume is still disabled.

Extend volume disabled

3. Delete drive D and retry.

Delete drive D

You cannot extend C drive, too.

Cannot extend C

4. Delete all volume in the Extended partition and retry.

Delete volume E

Delete the Extended partition.

Delete extended partition

Now, Extend Volume becomes available.

Extend available

As I said above, you cannot extend C drive in Windows Server 2012 in most cases.

Why cannot extend C drive in DM

There are 3 main reasons why you cannot extend C drive with Extend Volume function:

  1. You may use FAT32 file system. From Microsoft explanation, only NTFS and RAW format partition can be extended.
  2. There is no adjacent Unallocated space. Only when the Unallocated space is adjacent and at right side of C drive, you can expand C drive with the Unallocated space.
  3. You did not delete the adjacent Extended Partition. If the adjacent drive D is in the Extended Partition, you cannot extend C drive by simply deleting D. You should delete all volumes in the Extended Partition and then delete the entire Extended Partition.

Extend C drive without deleting

With 3rd-party server partition software, it is much easier to decrease and increase partition size. You can extend C drive without deleting. As long as there is free space in any other drives in the same disk, you can take free space out and add to C drive easily.

1. Download the application, right click the drive that has plenty of free space, and then select “Allocate Free Space”.

Reallocate space

2. In the pop-up window, type the amount of free space to take out, and then select C drive in the drop-down box.

Add space to C

3. Press Apply on main window to proceed. As you see, C drive increased 15GB space.

C drive extended

This application supports all types of hardware RAID, such as RAID 0, 1, 5, 10. VMware/Hyper-V, HDD, SSD, USB disk are all supported. Download to try or see full features.

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