I was quite confused on finding the free disk space for a volume that was mounted on the D Drive. It was not possible for me view the size in GUI. However, I was able to find the free disk space using the command “FSUTIL”.

For example:
C:\>fsutil volume diskfree c:
Total # of free bytes : 22047387648
Total # of bytes : 34365186048
Total # of avail free bytes : 22047387648

Similarly we can use the same command to find the free disk space on the volume that is already mounted.

C:\>fsutil volume disk free c:\windows\Backup

Its simple and easy. This will help you when you get automated tickets for the low disk space.