Laru: About one week earlier my C: drive had nearly 110GB free (24% free). Then more recently Windows Explorer said my C: drive had only 6% free (with no additional big files added by me). So I started looking for a space consumption (memory leak) problem on drive C:.
This link was the first I came across.
https://answers.microsoft.com/en-us/windows/forum/all/my-c-drive-is-full/b40fd83a-d55e-47e9-96db-74bd1d4a89e6
The comment on that thread by DaveM121 says Windows Explorer is useless (in this situation). I am inclined to agree with that. I had a space leak on my machine and Windows Explorer just was not finding it for me. Then I started using TreeSize which did find it for me (right away).
This link was the second I came across.
https://www.groovypost.com/howto/map-hardrive-usage-find-hidden-files-windows-10-treesize-freeware/
On my machine, TreeSize said my C:\Program Files\Microsoft SQL Server folder was very much larger than the size value reported then by Windows Explorer. So I uninstalled SQL Server and reinstalled it again, but put some on drive D: (to save some space on C:, which is history by now).
I did not accurately know just how big the (non-leaking) SQL folder was when I decided to re-install it to D: drive. But I do now. Laru, your comment that the (non-leaking) SQL folder could (or should) have stayed on drive C: is correct. Even so my SQL install is working correctly, although it is split over the two disks. At this point I have learned how to install and un-install SQL so very well, that I can change the install configuration later efficiently if the need arises.
The total amount of space freed up on C: by the reinstall should only have been 14.8GB (see count below). So Laru you probably came to think there was something wrong. And indeed there was (a memory leak). But there was also about another 60GB freed up moreover on C: by the reinstall, which is what I was trying to recover. So again I think there must have been an on disk C: memory leak. The SQL reinstall appears to have fixed that completely now. Thanks to TreeSize for finding the right problem folder (right away).
C:\Program Files\Microsoft SQL Server, (4.8GB)
C:\Program Files (x86)\Microsoft SQL Server, (0.163GB)
C:\Program Files (x86)\Microsoft SQL Server Management Studio 18, (1.1GB)
D:\Program Files\Developer_ENU, (1.5GB)
D:\Program Files\Microsoft SQL Server, (11.0GB)
D:\Program Files\Microsoft SQL Server Reporting Services, (0.309GB)
D:\Win_10_Pro_Stores\Installed Softwares\MS SQL Server, (2.0GB)
The D: sum amount is 14.8GB (saved from C:)
Hope this clears the confusion.
Regards.