Inside Windows Storage: Server Storage Technologies for Windows 2000, Windows Server 2003 and Beyond

6.4 Nonprimary File Systems

Windows NT provides support for several different file systems, for various purposes. The primary, full-featured file system is NTFS. Microsoft has clearly indicated that the legacy FAT file system is primarily in maintenance mode, with no new significant feature development planned at all. Besides NTFS and FAT (described in the following sections of this chapter), the other file systems supported include

• An ISO 9660 “compliant CD-ROM file system (CDFS) for I/O on CD-ROM disks.

• Universal Disk Format (UDF), defined by the Optical Storage Technology Association (OSTA). Support for UDF was introduced with Windows 2000. UDF will be the successor to CDFS, which also supports DVD. Windows 2000 initially shipped with only read-only support, but read and write support shipped in Windows XP.

Note that often a single Windows system may be running multiple file systems. To elaborate, a single Windows system typically has multiple volumes, and not all of the volumes need to be operating with the same file system.

6.4.1 FAT File System

Windows 2000 supports an updated version of the FAT (file allocation table) file system, with the following highlights:

• There are two versions of the FAT file system: FAT16, which uses 16-bit pointers, and FAT32, which uses 32-bit pointers.

• FAT16 supports partitions up to 4GB in size, using 64K clusters. FAT32 can support partitions up to 32GB in size , using 16K clusters.

• The root directory can contain only 512 entries.

• Compression and security are not supported.