In this article we will talk about the WinSxS folder in Windows, the reasons of its constant growth and ways to clean up it. The C:\Windows\WinSxS directory is the repository of Windows components. This directory contains DLLs, binary and XML files necessary for installation and operation of various Windows roles or features. When installing the Windows updates (usually this happens every month), the new version of the updated component is installed on the system, while the old one is saved to the WinSxS folder (it is necessary to provide compatibility and make it possible to rollback to the previous versions of the components when you uninstall the Windows update).

The WinSxS directory has grown in size over time. Moreover, its size is not limited by anything (although in practice the size of the WinSxS folder in Windows 10 rarely exceeds 15-20 GB).

In this article, we’ll go over the safest ways to clean up the WinSxS folder on Windows 10 and Windows Server 2016/2019:

• Optimize the component store and remove old versions of Windows component files left after installing Windows updates;
• Features on Demand – allows you to remove unused Windows components from the disk;
• Enable NTFS compression on the WinSxS folder – a way to reduce the size of the WinSxS directory using the built-in compression of the NTFS file system.

How to Check the Actual Size of WinSxS Folder on Windows 10?

The easiest way to get the current size of the WinSxS folder on Windows is to open the properties of the %windir%\WinSxS folder in File Explorer (or use a PowerShell script). But keep in mind that most file managers (including File Explorer) show a slightly larger WinSxS folder size than it takes on disk.

The fact is that the WinSxS directory contains a large number of hard links (symbolic links) to system files in other folders. File managers, when calculating the size of the WinSxS folder, take into account the size of files referenced by hard links, but this is not correct.

You can find out the real size of the WinSxS folder on disk using the du tool from Sysinternals:
du -v c:\windows\winSXS

You can also analyze the size of the component store (WinSxS folder) using the DISM command:

Dism.exe /Online /Cleanup-Image /AnalyzeComponentStore

Deployment Image Servicing and Management tool
[==========================100.0%==========================]
Component Store (WinSxS) information:
Windows Explorer Reported Size of Component Store : 8.44 GB
Actual Size of Component Store : 8.15 GB
Shared with Windows : 5. 74GB
Backups and Disabled Features : 1.97 GB
Cache and Temporary Data : 438.31 MB
Date of Last Cleanup : 2021-02-22 20:37:29
Number of Reclaimable Packages : 1
Component Store Cleanup Recommended : Yes
The operation completed successfully.

As you can see, in this case, I can reduce the size of the WinSxS folder by (1,97 + 0,44) Gb.

How to Clean Up the Component Store (WinSxS folder) on Windows?

The fastest and easiest way to clear the Windows Component Store (the WinSxS folder) is to optimize the storage with the command:

Dism.exe /Online /Cleanup-Image /StartComponentCleanup

After cleaning is complete, check the current size of the component store:

Dism.exe /Online /Cleanup-Image /AnalyzeComponentStore

In my example, this reduced the size of the WinSxS folder by 2.4 GB.

The /StartComponentCleanup option has an additional /ResetBase option that allows you to remove all previous versions of components left after installing Windows updates. After that you won’t be able to remove installed updates or Service Packs, and the Uninstall button will disappear from the Uninstall an Update Control Panel item). To clean up old versions of components, run:

Dism.exe /Online /Cleanup-Image /StartComponentCleanup /ResetBase

You can also remove old update files using the “Disk Cleanup” wizard:

1. Run the cleanmgr command as an administrator;
2. Select the disk and in the next window, click the “Clean up system files” button;
3. Then select the “Windows update cleanup” option. The Disk Cleanup tool will show how much space you can free up by deleting old Windows update files. In my example, this is 324 MB. Click OK to start the cleanup.

After you finish cleaning up the component store using DISM, check how much disk space has been freed.
In addition, Windows 10/Windows Server?2016 Task Scheduler has a special automatic maintenance task that regularly optimizes and cleans up the WinSxS folder (same operation as DISM with StartComponentCleanup parameter). This StartComponentCleanup task is located under the \Microsoft\Windows\Servicing section of the taskschd.msc. This task runs in the background and automatically removes component versions older than 30 days that have been superseded by newer files.

You can start this task manually like this: