What is NTFS?

NTFS is a Microsoft file system. It was introduced in Windows NT and has been the default file system for every version of Microsoft Windows since. NTFS replaced the aged FAT file system and addresses most of FAT's shortcomings. NTFS has been continuously maintained and improved by Microsoft, and the current version provides secure data storage that meets the requirements of modern hardware and usage. However, NTFS remains a closed standard, Microsoft does not publish its API nor implementation details. Therefore only Microsoft operating systems can use NTFS natively, and even OS's that are capable of reading and writing to NTFS cannot be installed on hard disks formatted as NTFS.

The NTFS acronym stands for New Technology File System. The name derives from the implementation of very innovative data storage techniques that were refined in NTFS. While none of the techniques are unique to NTFS, it is the first time that so many innovations were released at once on a production file system. The FAT file system had long been criticized for not including some of the more obvious improvements such as journaling, disk quotas, and file compression. However, these improvements made NTFS incompatible with previous versions of Windows, and also with hard disk tools designed for FAT file systems. For example, data recovery tools such as GetDataBack and partitioning tools such as PartitionMagic would run on Windows NT, yet could not function on the newer file system. This led to much frustration with users who had purchased licenses for these products before upgrading to Windows NT.

Although designed specifically for use with Microsoft Windows, work has been done to provide some level of interoperability between NTFS and other operating systems (notably Mac OS-X and Linux). Most of the projects involved in deciphering the NTFS API have been open source efforts, however a few proprietary solutions have come to light. Microsoft keeps the NTFS a close-guarded secret, so all work must be reverse engineered. Read access has proven to be relatively easy to implement, and all current interoperability solutions provide full read access for uncompressed files and folders, with the exception of ADS files. While the LZ77 compression algorithm optionally used in NTFS compression is well documented, the level compressed file readability varies from implementation to implementation. Also, no NTFS interoperability solution currently provides reliable write access. Most implementations limit the amount of writes that they will make to the file system to prevent corruption, while others provide read-only access.