Not relevant to the size of the vdisk unless you do this
Since that disk is 100% full, basically you either need to do the above which keeps the vdisk the same size as what windows reports is used, or shrink the vdisk.
Basically by default, the vdisk no matter what you do will always expand to the size you've set for it.
IE: say from a fresh install of Windows and a new vdisk Windows says that 1TB is used. the vdisk size on the hard drive will also be 1TB
Now copy 1 TB of files to the VM. Windows will say that the used space is 2TB, and the vdisk will also be 2TB.
Delete those 2TB of files, windows will report 1TB used, but the vdisk is still 2TB
Copy over another 1TB of files and windows says 2TB used, but the vdisk now takes up 3TB and so on until the vdisk takes up the maximum size you've specified or you run out of space on the drive storing it (which is what's happened here due to overhead etc)
Oh yeah, that drive that you think is 10TB isn't. It's only an 8TB (7.7TB after formatting)