The Master File Table (MFT) contains an index of the files on an NTFS drive. The MFT is the Master File Table which contains the identifying information used by the file system to manage file storage. My CCleaner just randomly started cleaning. What is free disk space? Free disk space, also called as unused disk space, is the space on the disk where there's no data saved. What Does Wipe Free Space Mean In CCleaner? CCleaner.