NTFS supports compression on volumes, folders, and files. Files that are compressed on an NTFS volume can be read and written by any Windows-based application without first being decompressed by another program; decompression happens automatically during the file read. The file is compressed again when it is closed or saved.

雖然知道有這個function 很久，不過這是第一次用，
我的259G partition 用了10 小時才轉完，多出了25Gb空間!

Insufficient System Resources Exist to Complete the API.

http://support.microsoft.com/kb/909095