Windows File Systems

The various flavours of Windows all need to support older file systems for backward compatibility, as well as new file systems that provide better functionality. The following is a list of most of the supported file systems.

FAT16 and FAT32

FAT (File Allocation Table) is the file system that has been around since MS-DOS days. Bill Gates supposedly created the original FAT system in 1976, in a hotel room in Albuquerque. It has been superseded by better systems, but is still used for floppy disk support. The original FAT, or FAT16 system supports volumes up to a maximum size of 4 GB. The FAT32 file system will support volumes up to 8 TB (Windows 2000/3 will support 127GB volumes, but can only create 32GB volumes). The FAT32 system also uses a smaller cluster size, so it uses disk space more efficiently than FAT16.


CIFS is an open system which lets groups of users to work together and share documents across the Internet. It is discussed in the CIFS page.

Compact Disk File System

The Compact Disk File System (CDFS) replaced the MS-DOS MSCDEX utility. It is used to read data from CD-ROM devices.

Universal Disk Format

Universal Disk Format (UDF) in turn replaced CDFS. The Optical Storage Technology Association (OSTA) defined the UDF file system to work with CD, DVD and Magneto Optical storage.
Windows 2000 and 2003 can read UDF version 1.02 and 1.50 files. Microsoft plan to introduce read/write support in the Vista release of Windows

Offline Files

Offline Files was developed by IntelliMirror, and was introduced to Windows 2000. It is intended for mobile users who sometimes log into a network, and sometimes work standalone, and allows them to access locally cached versions of networked files, if they are working stand alone. They can also use locally cached versions of files when they are logged into the network, which can greatly improve network performance.

Windows uses the Synchronisation Manager feature to keep local and remote files in step. Three Synchronisation options are available:

  • Manual Caching for Documents
    This option provides offline access to only those files that someone using your shared folder specifically (manually) identifies. This caching option is ideal for a shared network folder containing files that are to be accessed and modified by several people. This is the default option when you set up a shared folder to be used offline.
  • Automatic Caching for Documents
    This option makes every file that someone opens from your shared folder available to that user offline. However, this setting does not make every file in your shared folder available offline, only those files that are opened. Files that are not opened are not available offline.
  • Automatic Caching for Programs
    This option provides read-only access to certain files that are not to be changed, typically .exe and .dll files. Automatic Caching for Programs reduces network traffic once cached, because offline files are opened locally without accessing the network versions in any way, and generally start and run faster than the network versions.

File Replication Service (FRS)

File Replication Service (FRS) was introduced in Windows Server 2000. FRS will synchronise files and folders locally, or between remote servers. It uses the NTFS change journal to identify files that have changed, and must be replicated. It does not provide the same synchronous copy facilities as hardware mirroring, as remote data will not be copied synchronously, that is, the remote data is not guaranteed to be exactly the same as the local data.

FRS can be used in conjunction with DFS to make data on remote sites highly available. FRS is not a replacement for tape backups, as data corruption, accidental deletion and viruses will be replicated to failover disks.

To activate FRS,

  • go into 'Distributed File System'
  • Click the domain DFS root or link for which you want to manage replication
  • On the Action menu, click Properties
  • On the Replication tab, click Schedule
  • The replication schedule appears, with blue representing the times when replication is available, and white representing the times when replication is not available
  • On the replication schedule, click to select an hour or drag to select a range of hours
  • Enable or disable replication for the selected time period or periods as follows:
    • To enable replication, click Replication Available
    • To disable replication, click Replication Not Available

FSR was enhanced in Windows 2008 and renamed DFSR (Distributed File System Replication). The main advantage is that DFS will only replicate those parts of files that have changed, rather than replicating an entire changed file.


NTFS was introduced in the Windows NT operating system. Its advantages and disadvantages are discussed in the NTFS page


ReFS was introduced with Windows Server 2012. Its advantages and disadvantages are discussed in the ReFS page


DFS (Distributed File Sharing) was introduced in Windows NT, and then developed further in Windows 2000 and 2003. The idea behind DFS is to hide the location of a file or directory from the user, so that if a file or disk moves around the user is unaware of the details. This is all discussed in the DFS page

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