File Systems

Support for FAT32 is new in Windows 2000. The FAT32 on-disk format and features on Windows 2000 are similar to those on Windows 95 OSR2 and Windows 98.

The size of a FAT32 cluster is determined by the system and can range in size from 1 sector (512 bytes) to 128 sectors (64 KB), incremented in powers of 2.

Note

The use of 64 KB clusters in FAT32 can lead to compatibility problems with certain programs. The maximum recommended size cluster for a FAT32 volume is 32 KB.

Since FAT32 requires 4 bytes to store cluster values, many internal and on-disk data structures have been revised or expanded. Most programs are unaffected by these changes; however, disk tools which read the on-disk format must be updated to support FAT32.

The most significant difference between FAT16 and FAT32 is the maximum number of clusters supported, which in turn affects a volume's maximum size and storage efficiency. FAT32 breaks the 4-GB volume limitation of FAT16 by extending the maximum number of clusters to over 4 million. FAT32, as implemented in Windows 2000, can mount a volume as large as 127 GB. Due to the greater number of available clusters within FAT32, each cluster can be made smaller for a particular volume, making data storage more efficient. If you have a FAT16 volume between 2 and 4 GB in size, a 64-KB cluster is used; with FAT32, volumes ranging in size between 256 MB and 8 GB use a 4-KB cluster.

The largest possible file for a FAT32 volume is 4 GB minus 2 bytes. FAT32 contains 4 bytes per cluster in the file allocation table; FAT16 contains 2 bytes per cluster; and FAT12 contains 1.5 bytes per cluster. A FAT32 volume must have at least 65,527 clusters, but no more than 4,177,918 clusters.

In Windows 2000, you cannot format FAT32 volumes greater than 32 GB. Use NTFS to format larger volumes. For more information about why it is recommended that you format all Windows 2000 volumes with NTFS, see NTFS File System earlier in this chapter.

Note

The Windows 2000 Fastfat driver enables you to mount and fully support a FAT32 volume larger than 32 GB that was created by another operating system.