Windows 10 $Extend folder eating up disk space

Question

I am struggling for a while with the problem, my computer running out from space time-to-time. I didn't see anything on the Storage analysis of Windows 10 but the "System and Reserved files" is over 250-300 GB.

Every time if I restart my computer, this size is reduced back to normal 25 - 30 GB.
The computer is used for development, usually running all the time (without restart) but now running out of space in one day.
Yesterday I installed the WizTree (earlier I used WinDirStat what was not able to show what eating my space) and got the result the $Extend hidden folder is using 294GB from the 500GB.
Any idea what could cause this?

Answer 1

@Istvan Nyari
Hi,
'System Volume Information' is almost all reclaimable.

Windows keeps backups of all the windows updates you have received. These can be safely deleted. All your restore points are kept in the 'System Volume Information' folder and it's this that's taking up a lot of space. The safe way to clean up both is to run Disk Clean up and click its 'Clean up system files' button.

On the 'More options' tab you can delete all but the most recent restore point. On the 'Disk Cleanup' tab you should see 'Update backup files', tick the box next to this (and anything else you think you won't want to keep) then click OK.

The system and reserved files may continue to consume space due to a certain service log that could add to your system as a result of multiple operations. At this moment, we suggest that you run CHKDSK command prompt by following the steps below:
Plug in your external hard drive, USB drive or memory card to PC.
Open Command Prompt; then, press Windows key + X button and select the Command Prompt (Admin) option.
In the new Command Prompt window, type chkdskE: /f /r. Here, you should replace E with the drive letter of your external hard drive or USB device.
Note: This operation will run CHKDSK to check and repair file system corruption, errors, corruptions or bad sectors on the external hard drive or USB disk.
It is also advisable to manually delete files in C:\Windows\Logs\CBS. To do so, follow the steps on this article: Clean Up Component-Based Servicing logs
https://social.technet.microsoft.com/wiki/contents/articles/38259.clean-up-component-based-servicing-logs.aspx

Hope above information can help you.

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Answer 2

@Istvan Nyari
Hi,
$Extend is a system reserved folder used by NTFS v3.0 or later. These files are required by the OS and should not be deleted.
The files in $Extend\$Deleted\ are files that some Windows program requested deletion for, that all open handles allow deletion of the file, and that while deleted aren’t actually gone.
Normally on reboot those files shall be cleared.

If you really want to delete it, then you'll need to perform a clean install of Windows 10.

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