AfterDawn: Glossary


NTFS or New Technology File System was introduced as the standard file system structure of Microsoft's Windows NT system. This file system has remained the standard for all subsequent file systems after the release of Windows NT including the newest, Windows Vista.

NTFS replaced the aging FAT32 file system common to the MS-DOS based Windows operating systems. What the file system gained in its replacement was improved disk space utilization, improved performance, reliability and support for metadata. In addition, the file system was given additonal security through its built in access control lists.

NTFS has undergone several revisions with versions 1.0 and 1.1 reserved as test file systems, the first version which was deployed in Windows NT 3.51 and 4.0 was NTFS v1.2. The file system saw major upgrades and 2 full version numbers to 3.0 in its Windows 2000 integration, while NTFS 3.1 is currently being used in Windows XP and Windows Vista.

NTFS as a whole focuses on everything to do with the files themselves. How data is stored on the hard drive is goverened by the NTFS file system. NTFS prefers to store data as metadata. Metadata in its most simplistic definition is extra data associated with a file that tells the operating system and/or user what attributes are inherant to a specific file. For example, if a digital picture is stored on your hard drive it could contain data that tells the resolution, time taken, time altered, last viewed etc. This data is not essential to the function of the file, however in other forms, can be absolutely essential for indexing of files within the hard drive.

Some of the key features of NTFS are as follows:

  • Alternative Data Streams (ADS) - which allows files to be associated with more than one data stream which aids in keeping files hidden from users who do not know the specific ADS name of the hidden file.
  • Disk Quota - which allows administrators of NTFS systems to allocate specific amounts of disk space for users to have access to.
  • Volume Mount Points - similar to Unix, this allows multiple file systems to be attached to a single partition without the need for an additional drive letter.
  • Hierarchical Storage Management (HSM) - transfers files that are not used for some time to a non-essential storage area and reparses the files when called upon. This practice helps minimize defragmentation of the hard drive as well as speeds up indexing.
  • Volume Shadow Copy (VSC) - allows old data to be overlaid updated data in the event a user needs to revert a file back to a specific revision. This also helps in data recovery efforts where important data may have been lost.
  • File Compression - the ability to compress files into smaller chunks to streamline disk space.
  • Encrypting File System (EFS) - works in conjunction with the Microsoft service, CryptoAPI to create a symetrical key and public key to encrypt a file, directory or entire parition so that data can only be retrieved by the user who holds the public key.

NTFS isn't without its limitations either. Some of them are:
  • Maximum File Size - NTFS was first developed when it was thought that a Gigabyte (Gb) of information was an incredible amount of data potential. As a result, the NTFS master boot record is only capable of indexing 2 Terabyte (Tb) of information. For systems larger than 2Tb, dynamic volumes must be created. With the default 4Kb clustering, an NTFS dynamic volume can hold a maximum of 16Tb of data. If the clustering size is changed to 64Kb, the maximum size of an NTFS dynamic volume can hold a maximum of 256Tb of data.
  • Maximum File Size - Theoretically a file on NTFS cannot exceed 16Tb.


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