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Disk Cleanup is an essential Windows system tool which allows you to delete various unnecessary files created by the OS to save space on your disk drive. By default, it works in a simpler mode which allows you to delete only the files related to your current user account. You can switch it to the extended mode, which allows you to delete more unused files such as the ones used by Windows Updates, or service packs and so on. In Windows 10, the extended mode was updated to add one more feature. Now it provides a System compression option. Let's explore what it is about.

To see the feature in action, you need to run the Disk Cleanup app as Administrator or switch it from the regular mode to extended by pressing the Clean up system files button.

  1. Type cleanmgr at the Start screen or in your Start Menu search box.
  2. Press Ctrl+Shift+Enter to open it directly as administrator. You can also right click it in the search results and select the Run as administrator option from the context menu.
You need to wait for a few seconds before the Disk Cleanup window will appear on the screen. There you will find the new System Compression item:

It is not clear what data exactly gets compressed, but from its description it appears that it uses the built-in NTFS compression to compress files and free up some disk space. Longtime Windows users will remember that Windows XP had a similar "Compress old files" option in Disk Cleanup which was removed in Vista. Compressing data can free up a large amount of space from your disk drive. If you have a Windows 10 device with a limited amount of disk space, then this feature is a welcome addition. Anyway, this feature is not documented yet.


Staff member
Could it be similar to WIMBoot (Windows Image File Boot)?

"In a standard Windows installation (without WIMBoot), every file is written to disk at least twice: once in the compressed form for recovery, and once in the uncompressed form in the applied image. When the push-button reset feature is included, the compressed image remains on the PC. Having both the Windows installation and recovery image on the device can take up a lot of disk space.

When installing Windows with WIMBoot, you write the files to the disk only once, in compressed format. Next, you apply a set of pointer files onto the Windows partition that point back to the compressed files in the Images partition. When the user adds files, apps, or updates, they're added onto the Windows partition.
In WIMBoot, your WIMBoot image is also used as the recovery image, saving disk space."


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