FAT32 File System [Files]

The FAT file system organizes data on fixed and floppy disks. The main advantage of FAT file system volumes is that they are accessible by MS-DOS, Microsoft Windows, and OS/2 systems. The FAT file system is the only file system that is currently supported for floppy disks.

The FAT32 file system is the most recently defined file system based on the FAT file system format, which is included with Windows 95 OSR2, Windows 98, and Windows Me. The FAT32 file system uses 32-bit cluster identifiers, but reserves the high 4 bits, so it has 28-bit cluster identifiers.

Valid file names have the following syntax:

[[drive:]][[directory\]]filename[[.extension]]

The drive parameter must name an existing drive and can be any letter from A through Z. The drive letter must be followed by a colon (:).

The directory parameter specifies the directory that contains the file directory entry. This value must be followed by a backslash (\) to separate it from the file name.

If a specified directory is not in the current directory, directory must include the names of all directories that are in the file path, separated by backslashes. The root directory is specified by using a backslash at the beginning of the name. For example, if the directory ABCD is in the directory SAMPLE, and SAMPLE is in the root directory, the correct directory specification is \SAMPLE\ABCD. A directory name consists of any combination of up to 8 letters, digits, or the following special characters: $ % ' – _ @ { } ~ ` ! # ( )

A directory name can also have an extension that is any combination of up to 3 letters, digits, or special characters that are preceded by a period (.).

The filename and extension parameters specify a file. The filename can be any combination of up to 8 letters, digits, or the special characters previously listed. The extension can be any combination of up to 3 letters, digits, or special characters that are preceded by a period (.). The filename can also include embedded spaces, which are spaces preceded and followed by 1 (one) or more letters, digits, or special characters. For example, disk 1 is a valid value for filename.

The FAT file system volumes are case insensitive, and do not distinguish between uppercase and lowercase letters.

FAT File System Features

The following features are supported on FAT file systems:

• Defragmentation

• Volumes and volume mounting

• Opportunistic locks

  An opportunistic lock (also called an oplock) is a lock that a client places on a file located on a server. Typically, a client requests an opportunistic lock so it can cache data locally to reduce network traffic and improve response time. Opportunistic locks are used by network redirectors on clients with remote servers, and by client applications on local servers.

  Opportunistic locks coordinate data caching and coherency between clients and servers, and among multiple clients. Data that is coherent is data that is the same across the network. That is, if data is coherent, data on the server and all the clients are synchronized.

  For more information, see Opportunistic Locks.

Default Cluster Sizes

The following table identifies the default FAT32 file system cluster sizes.

Because FAT32 file system cluster sizes can be as large as 32 KB, the FAT32 file system has a theoretical ability to work with 8-terabyte (TB) volumes. Although Windows 2000 works with existing FAT32 file system volumes of larger sizes that are created in other operating systems, it limits new FAT32 file system volumes to a maximum of 32 GB. The FAT32 file system's higher potential cluster numbers enable it to manage disks more efficiently than the FAT12 file system. It can handle up to 128-MB volumes with 512-byte clusters.