Deeper understanding of SFC and DISM scans

[Lekro44]

Hello,

Out of curiosity I'd like to know what does SFC actually scan. Meaning, what folders. Does it scan the built in apps? The user profile with NTUSER.DAT? If I complete this scan what is included and excluded from it?

Same applies to the command DISM -Online -Cleanup-Image -RestoreHealth. What is the windows image that it scans exactly?

If anyone knows the answer to these, I'm very interested.

 

[Colif]

Finding what SFC scans exactly is difficult, I believe you could look in the cbs log and see what it shows there. Look under More info here - https://support.microsoft.com/en-au/help/929833/use-the-system-file-checker-tool-to-repair-missing-or-corrupted-system

DISM: The image it uses is a compressed copy of the install files used when Windows was 1st installed. When you install Win 10 it copies the image onto your PC before it restarts and decompresses the image to install it on PC.
So the image DISM uses is the original installation files unless you have received a version update since then, as they replace the image with a newer version of win 10 so that DISM doesn't freak out at all these newer versions of files it uses.

Sometimes the images get corrupted themselves and one way to fix them is an extended version of DISM that uses a Win 10 ISO to replace the corrupted files. It is run in command prompt (I am sure there is a variation for powershell) - DISM /Online /Cleanup-Image /RestoreHealth /source:WIM:X:\Sources\Install.wim:1 /LimitAccess

Maybe too much info on dism - https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/dism---deployment-image-servicing-and-management-technical-reference-for-windows