Get free disk space of a Windows mount point remotely

Does anyone know of a way to get the free disk space of a Windows mount point on a remote system without using WMI?

For example, GetDiskFreeSpaceEx returns the following values:

C:\ - 29 GB
C:\MountedDir - 50 GB

When run remotely on a Windows 2003 server (orig_server is 2008 R2) it reports the following:

\\orig_server\C$ - 29 GB开发者_如何学编程
\\orig_server\C$\MountedDir - 29 GB

Anyway to get the true space of MountedDir remotely without WMI?

[UPDATE] I found that if the target server AND the requesting server are both Windows 2008 R2 I get:

\\orig_server\C$ - 29 GB
\\orig_server\C$\MountedDir - 50 GB

Apparently Windows 2008 R2 (only if both are 2008?) fixes this. Does anyone know of any documentation that confirms this and explains the boundaries of the scenario?

I would guess that the original SMB protocol does not support mount points, when both the server and client is >=NT6, they can use SMB2 which probably why it works correctly when both are Server 2008