Fixed: Unable to Shrink C Drive in Windows 10/8/7

February 14, 2019

This article presents how to disable the unmovable files and shrink C drive at most under the help of powerful disk management software-AOMEI Partition Assistant.

Scenario

In order to create new partition to store individual data, I want to shrink C drive from 200 GB to 100 GB. When I enter Windows 10 Disk Management to start, the Shrink option is disabled no matter what value I type in the box behind “enter the amount of space to shrink in MB”. And the message shows that you can’t shrink a volume beyond the partition where any unmovable files are located. But what’s baffling is that there is 128 GB free space on C drive. What is wrong with it? Why Disk Management is unable to shrink C drive even there is free space on partition C.

Unable to Shrink C Drive

Solution: Disable the unmovable files

Actually, the answer is as same as the Disk Management message shows that the shrink space of C drive is limited by unmovable files such as Hibernation, Page files and system protections. These files can’t be moved automatically by Windows built-in tool Disk Management, so you’ll need to manually disable the unmovable files.

As these files are hidden, you should uncheck Hide protected operating system files and check Show hidden files to see these files in Explore at first.

Then, how to disable the unmovable files on Partition C will be shown in next part. (It is recommended to re-enable them after shrinking C drive.)

  • Disable System protection:Press “Win + R”< enter “SystemProperitiesProtecion.exe”< press “Enter”< click C drive< click “Configure”< select “Disable system protection”< click “Apply”< click “Yes”<restart

  • Disable Hibernation:Click “Start”< type “CMD” in the Search box< right click “cmd”< choose “Run as administrator”< enter “powercfg.exe /hibernate off”<press “Enter” <restart

  • Disable Page files: Press “Win + R”< type “SystemPropertiesPerformance.exe”< Press “Enter”< click “Advanced” < click “Change under Virtual Memory”< uncheck “Automatically manage paging file size for all drives”< click C drive< set paging file size to No paging file< click “Set” < click “OK”< restart

  • Disable the kernel memory dump:Click “Start”< select “Control Panel”< click “System and Security”<click “System”< click “Advanced system settings”< click “settings” under “Startup and Recovery”< Change the drop down menu under “Write debugging information to “None”.

Notice: You can restart computer after all the above set.

Next, you can gain a large space to shrink the size of partition C.

*You can run Disk Cleanup on the disk and Disk Defragment for HDD to get more free space on C drive.

*Do not forget to re-enable these unmovable files after changing partition size of C drive.

Shrink C drive with AOMEI Partition Assistant

It is definitely possible to decrease the size of partition C after disabling the unmovable files on C drive. However, you still can not shrink C drive beyond half. Fortunately, you can turn to apply powerful and reliable third-party software-AOMEI Partition Assistant Standard (free). It allows you to shrink Partition C without disabling unmovable files when Windows Disk Management can’t shrink C drive. It can work on Windows 10/8/7/XP. If you want to apply it on Windows Server such as Windows Server 2016 and Windows Server 2012, you can upgrade it to AOMEI Partition Assistant Server.

To change partition C size to small, you need to download AOMEI Partition Assistant, install and run it at first. Then, you can follow steps listed below (Take shrinking C drive in Windows 10 as an example).

PS: It is strongly recommended to backup important data before changing partition size.

Step 1: Right click C drive and choose “Resize Partition”.

Resize System Partition

Step 2: In the pop-up window, shrink partition C via dragging the slider leftwards or change the value behind “Partition size”. Then, click “OK”.

Shrink System Partition

PS:

  • If you need to specify the location of C drive, you can tick the box before “I need to move this partition”.

  • If your disk is SSD, click “Advanced” < put a tick before “Allow partition alignment…” to make SSD at great state.

Step 3: You can review the operation in main interface. Check the pending operation and click “Apply”< “Proceed” to shrink C drive.

Apply Resize Partition Shrink

Proceed Shrink C Partition

 And you shall gain an unallocated space after decreasing the size of C drive via AOMEI Partition Assistant.

Notice:

  • A reboot is required as this program will run under AOMEI Partition Assistant PreOS Mode.

  • When you need a new partition to store data or install another operating system, you can create new partition with the unallocated space on the hard drive. Or just create new a partition from C drive.

  • When you need to extend the partition size of another drive with the unallocated disk space, you can take advantage of the function “Merge Partitions” that allows you to add the unallocated space to any partition on the same disk whether the unallocated space is right behind the partition or not.

Verdict

When Windows is unable to shrink C drive due to unmovable files, it is acceptable to disable these files and shrink volume; but it is better to apply AOMEI Partition Assistant. With concise and user-friendly interface, this tool is simple to handle. Just within simple three steps, you can get an unallocated space to create new partition or extend partition. What’s more, AOMEI Partition many other features such as convert MBR to GPT and change serial number.