# Over 20GB of disk space is gone

disk-space

System drive, OS is Windows 7 x64 SP1 Ultimate.

• Windows Explorer shows 100GB of used space.

• TreeSizeFree shows 75GB of used space.

• Total Commander and FAR confirm TreeSizeFree's measurements (counting hidden files).

• Shadow copy is using up to 5GB with the current usage of 1.36GB.

• Running FAR from Win7 PE shows the same.

• Checkdisk shows no bad sectors. Disk is an OCZ SSD.

• SMART monitor suggests SSD condition is perfect.

Where is the rest of space gone?

Most Likely Problem: There's a large number of directories and files that even Administrator accounts do not normally have access to, especially in the ProgramData and Windows trees. Without doing something special, most space analysis programs aren't going to correctly account for the space they're using.
Using space analysis programs on the Windows folder is already fraught with problems anyway. The folders are densely hardlinked, and very few programs (including Explorer itself) can correctly handle that. In fact, the only one I know of offhand is Sysinternals' du.exe tool, when passed the -u flag.