Two virtually identical installations: C drive on one is 10GB larger

This is probably too elementary for words, but it's puzzling me. I have two desktops with essentially the same software installed on both, both with two SSDs, both running the same build of W10 Pro 20H2. I never install software to C if I can help it -- D is my applications and utilities drive; F is storage -- so C has only Windows and the few apps that won't permit custom installation, but when I check File Explorer I find that C is 31GB on one computer and only 21 on the other. I've run through the folders on C on both to see whether I can find the heavy culprit, but nothing obvious shows up. I have no Windows.old on either computer. Page files sized the same (2,048) on both.

Yeah, I know: 10GB is no big deal. But I sure would like to find that space-hog. Any ideas?

Wisewiz said:

....I've run through the folders on C on both to see whether I can find the heavy culprit, but nothing obvious shows up....

One thing you won't be able to see in File Explorer is how much space any system restore points occupy. They are stored in the hidden and protected System Volume Information folder which you don't have permission to explore. Check to see how much each PC is using.

Change System Protection Max Storage Size for Drive in Windows 10

Thanks for responding, friends. I do, indeed run Disk Cleanup (plus System Files) once each week on both, and I have my System Restore files always down to just the most recent one. I let Google and Mozilla put Chrome and Firefox on C, but I watch and weed the accumulation of cache and cookie files frequently. Please keep the suggestions, coming, you wizards. I'm in a Sherlock Holmes frame of mind today.

These are work computers, so no games, no photos, no vids, no music, fewer than 20 installed applications/utilities (same on each). Running bare bones for speed and functionality, but somebody stole 10 Gigs more of my main disk on one than on the other.

TreeSizeFree when run as administrator has no permissions limitations, allowing you to see things that Explorer can't.

TreeSize Free Portable (directory size and usage analyzer) | PortableApps.com

Gittin' 'er now. Back soon.

Okay: Windows is 4GB larger and Program Files is 4GB larger on system A than on B. I'm sure I can figure out what the heavyweights are in program files, but I have no idea what to look for ---- wait, I bet I can use that tree program again to check just the Windows folder. Back soon.

Well, that narrows it down. Why would SxS and Sys32 be significantly larger on one?


- - - Updated - - -

Okay, I used that little gem of a tree program (THANKS, Bree, it's a keeper!) to drill down and down and down, and what I've decided on the evidence is that I have no hogs; only a bunch of not-very-substantial piglets here and there, and they all add up to the 10 Gig difference between the two C drives. Given that the two machines are used slightly differently, and their record-keeping functions thus have different data, I am no longer either surprised or concerned.

Many thanks to Navy and Bree (Dr. Watsons 1 & 2) for helping me to solve this case. Now back to Scotland yard.

Wisewiz said:

...Well, that narrows it down. Why would SxS and Sys32 be significantly larger on one?...

WinSxS is the Component Store. 'Disk Clean up - clean up system files' should normally clean up the windows updates held here, but I've noticed for a few CUs recently that it failed to find anything to clean up. Use DISM to analyse your component store and see its actual size, then clean it up using DISM.

Analyze Component Store (WinSxS folder) in Windows 10

Clean Up Component Store (WinSxS folder) in Windows 10

Bree, Many thanks for all this time you've spent helping an old man with a not-terribly-important matter.

I used the DISM reset option, and it sucked 3 Gigs of unnecessary stuff from SxS. Yay! The rest is too diffuse and insubstantial to bother with, now that I know there's nothing major causing the size difference between C on #1 and C on #2. Thanks again. I'm going to mark this Solved now. As we say up here in the Great White North, "Have an iced eh?" (which sounds exactly like what you folks say in the Tropical South, if you say it carefully). BTW: We're having snow tomorrow in Southern Ontario.

Wisewiz said:

Bree, Many thanks for all this time you've spent helping an old man with a not-terribly-important matter.

I used the DISM reset option, and it sucked 3 Gigs of unnecessary stuff from SxS. Yay!