huge increase is disk space used on Win 8.1 laptop after upgrade to Windows 10

[soybean]

For those of you who upgraded a Win 8.1 system to Win 10 during the free upgrade period, have any of you noticed a surprisingly large increase disk space used after the upgrade.  I have to admit I do not recall exactly how much space was consumed on drive C before the upgrade but I believe it was under 50GB.  After the upgrade, right clicking on drive C and selecting Properties shows 175GB used.  In contrast, a desktop system with Win 10 (from Microsoft Insider program) has 40.3GB consumed on drive C and a system upgraded from a retail version of Win 7 Pro to Win 10 Pro has about 37.8GB used on drive C. 

I will list where I see major areas of disk space consumption:

Users 14.2GB
Windows 18.5GB
Windows.old 16.2 GB
Windows10Upgrade 15.4GB

Documents, Downloads, Music, Pictures, and Video account for less than 10GB.

I'm wondering whether this situation will change by itself after the 30 day period for going back to the previous version expires.  At some point, the Windows.old folder can be deleted.  But, that would still leave a perplexedly large amount of drive space consumed.   

[Calum]

Interesting.
So you're saying that those are the four largest folders showing, totaling roughly 65GB - I'm assuming that your program files folders aren't empty, but if they're smaller than the above, that does leave a lot of space unaccounted for.
Have you checked to see if system restore is using a large amount of space, or if Windows has perhaps created you a large page file?  I once had Windows go a little overboard and create me something like a 30GB page file which was less than helpful.
Basically just trying to think of what could be taking up that space without being obvious or included in what you've checked.  You're correct that the Windows.sold and Windows10Upgrade folders can be removed using disk cleanup once 30 days have passed (that reminded me to check mine...since the Windows 10 Anniversary upgrade the other day I now have a 16GB Windows.old folder myself, time to nuke that!).

[soybean]

Calum, thanks for your response to my post.  Since I posted about this, I ran the Windows disk defrag utility. After that, drive space used actually increased.  It is now 199GB.  Oh, by the way, I checked the setting for pagefile and it is set to allow Windows to control the size; it currently shows 1218MB as the size. 

I downloaded a hard drive graphing tool called HDGraph to see whether it might shed some light on the situation.  I captured the graph created by HDGraph and am inserting it here.  As you can see, it shows about 131.31GB as unidentified files.  In the lower right corner, it says "284 elements skipped due to scan errors".  If I click on the text below below that info, a panel pops up showing a list of those 284 elements. 


[attachment deleted by admin to conserve space]

[Calum]

Interesting.  Curious - have you tried running that utility as administrator?  Just wondering whether the "unknown files" are showing that way because you don't have direct permissions on them...

[BC_Programmer]

"unknown files" is the difference between the total size of the files that HDGraph tallied and the Total used space reported by the drive (total size-used space).

Files not being accessible is one reason, either via security settings or otherwise, but that is a massive amount of files to be "locked out", I don't see any "Unknown files" listed with the program, even when not running it as admin, so it's certainly atypical for that to be the case.

As to the "original" issue regarding disk space, Both my Laptop and my desktop are on Windows 10 upgraded from Windows 8.1. My Desktop system has a 44.4GB Windows folder and my laptop has a 36.6GB Windows folder.

C:\Windows\Installer consumes the majority of the space on both systems; I notice that it's not present on the screenshot, which seems to suggest that perhaps that folder (which b asically saves all the Installer packages for all software and also has all installed patch files/updates) may be owned by another account such as "TrustedInstaller" and can't be enumerated?