Microsoft Corporation Staff, IT Professional Staff - Microsoft Windows 2000 Server Operations Guide

Table 3.9 provides a comparison of FAT16 and FAT32 cluster sizes according to drive size.

Table 3.9 Cluster Sizes of FAT16 and FAT32

There are additional differences between FAT32 and FAT16:

• FAT32 allows finer allocation granularity (approximately 4 million allocation units per volume).
• FAT32 allows the root directory to grow (FAT16 holds a maximum of 512 entries, and the limit can be even lower due to the use of long file names in the root folder).

Advantages of FAT16

Advantages of FAT16 are:

• MS-DOS, Windows 95, Windows 98, Windows NT, Windows 2000, and some UNIX operating systems can use it.
• There are many tools available to address problems and recover data.
• If you have a startup failure, you can start the computer with an MS-DOS bootable floppy disk.
• It is efficient, both in speed and storage, on volumes smaller than 256 MB.

Disadvantages of FAT16

Disadvantages of FAT16 are:

• The root folder can manage a maximum of 512 entries. The use of long file names can significantly reduce the number of available entries.
• FAT16 is limited to 65,536 clusters, but because certain clusters are reserved, it has a practical limit of 65,524. Each cluster is fixed in size relative to the logical drive. If both the maximum number of clusters and their maximum size (32 KB) are reached, the largest drive is limited to 4 GB on Windows 2000. To maintain compatibility with MS-DOS, Windows 95, and Windows 98, a FAT16 volume should not be larger than 2 GB.
• The boot sector is not backed up.
• There is no built-in file system security or file compression with FAT16.
• FAT16 can waste file storage space in larger drives as the size of the cluster increases. The space allocated for storing a file is based on the size of the cluster allocation granularity, not the file size. A 10-KB file stored in a 32-KB cluster wastes 22 KB of disk space.

Advantages of FAT32

FAT32 allocates disk space much more efficiently than previous versions of FAT. Depending on the size of your files, there is a potential for tens and even hundreds of megabytes more free disk space on larger hard disk drives. In addition, FAT32 provides the following enhancements:

• The root folder on a FAT32 drive is now an ordinary cluster chain, so it can be located anywhere on the volume. For this reason, FAT32 does not restrict the number of entries in the root folder.
• It uses space more efficiently than FAT16. FAT32 uses smaller clusters (4 KB for drives up to 8 GB), resulting in 10 to 15 percent more efficient use of disk space relative to large FAT16 drives. FAT32 also reduces the resources necessary for the computer to operate.
• FAT32 is more robust than FAT16. FAT32 has the ability to relocate the root directory and use the backup copy of the FAT instead of the default copy. In addition, the boot record on FAT32 drives has been expanded to include a backup of critical data structures. This means that FAT32 volumes are less susceptible to a single point of failure than FAT16 volumes.

Disadvantages of FAT32

Disadvantages of FAT32 include:

• The largest FAT32 volume Windows 2000 can format is limited in size to 32 GB.
• FAT32 volumes are not accessible from any other operating systems other than Windows 95 OSR2 and Windows 98.
• The boot sector is not backed up.
• There is no built-in file system security or compression with FAT32.

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