OK, so you have 1TB OneDrive storage in the cloud. Nice. But your puny little SSD is only 128 GB, and every last gig counts.
Sure, you could move your entire OneDrive folder to your secondary, mechanical hard drive. But you don’t want to do that. You work with lots of those documents all the time, and want them to be as speedy as possible. It’s just a few folders with big, old content that you would want to have somewhere else, but still synced to the cloud.
Turns out it’s perfectly possible. In fact, it’s so easy you’ll kick yourself for not thinking of it earlier. It probably works equally well with DropBox, GDrive etc.
Just create an NTFS reparse point within your OneDrive folder, to your secondary drive.
So, say for instance that you have OneDrive mapped to C:\Data\OneDrive, and you have a secondary disk with some big data in D:\BigData. Just open a command prompt, and go
MKLINK /J C:\Data\OneDrive\BigData D:\BigData
You data appears as a directory within C:\Data\OneDrive, and is synced to the cloud, but it actually resides on D: so no space is wasted on C: