Many users have C:\ with a small SSD and D:\ with a larger HDD.
Windows puts the user folders on C:\, which means that AppData, Downloads, and Documents for several users rapidly fill up the smaller disk. The whole point of the larger disk is user data.
Plenty of discussions (1, 2 3, 4, 5, 6, 7) make it clear that moving user data is difficult or risky, with sysprep, hardlinks, registry edits, and other deep technical work that is not suitable for non-technical users.
Even just moving Documents is blocked because of a link -- I think OneDrive did this -- putting Documents under C:\Users\MyName\OneDrive\Document. (And the user name is hardcoded instead of passed with a variable). And in any case, Documents is not the main culprit -- AppData is.
Is there an easy and safe way to set the user folders in D:\?
If not, it seems that the larger "data disk" with 900 GB is of little value other than perhaps manually moving movies to it.
Documentsis blocked by some sort of link that OneDrive shoved into the OS. – Joshua Fox Dec 05 '21 at 13:35