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FAT16
File Allocation Table (commonly known as FAT or FAT16) is supported by Windows XP Professional, all Windows operating systems, and DOS, as well as a host of other non-Microsoft OSes.
FAT is allocated in clusters, the size of which are determined by the size of the partition. The larger the partition, the larger the cluster size. The larger the cluster size, the more space "required" when using it to store data.
FAT file system cluster sizes
Partition Size Cluster Size FAT Type
0M to less than 16MB 4,096 bytes 12-bit
16M through 128MB 2,048 bytes 16-bit
128 through 256MB 4,096 bytes 16-bit
256 through 512MB 8,192 bytes 16-bit
512 through 1,024MB 16,384 bytes 16-bit
1,024 through 2,048MB 32,768 bytes 16-bit
As you can see, with a 2GB partition size, (the maximum allowed under FAT16 in most cases) if you were to save 50 different files, all 1024 bytes (1KB) in actual size (or to have 50 fractions of larger files "fall over" to the next cluster by that same amount), the amount of hard drive space used up would be 1,638,400 bytes (a little over 1 MB), for 51,200 bytes of actual data.
You can obviously see that this is a serious problem when there are thousands of small *.DLLs and other types of small files.
Also, with the advent of super-inexpensive hard drives that are 80GB in size, you can see where using FAT would be an issue as well.
In summary, there are "advantages" for using the FAT file system on a Windows XP Professional installation:
MS-DOS, Windows 95, Windows 98, Windows NT, Windows 2000, and some UNIX operating systems can use FAT16. If there is some reason to dual boot the system, FAT16 allows you the greatest number of options.
There are many software tools that can address problems and recover data on FAT16 volumes.
If you have a startup failure, you can start the computer by using a bootable floppy disk to troubleshoot the problem.
FAT16 is efficient, in speed and storage, on volumes smaller than 256 MB.
(Those 50 files I mentioned above, all 1024 bytes (1KB) in actual size, would use up "only" 409,600 bytes on a 400MB partition formatted with FAT16 and "only" 204,800 bytes on a 250MB partition.)
There are also some FAT16 disadvantages as well:
The root folder (usually the C:\ drive) has a limit 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. The largest FAT16 volume on Windows 2000 and Windows XP Professional is limited to 4 GB and uses a cluster size of 64 KB. To maintain compatibility with MS-DOS, Windows 95, and Windows 98, a volume cannot be larger than 2 GB. (Those 50 files I mentioned above, all 1024 bytes (1KB) in actual size, would use up 3,276,200 bytes of hard drive space to store 51,200 bytes of actual data on a 4 GB FAT16 partition used in this scenario.)
FAT16 is inefficient on larger volume sizes, as the size of the cluster increases. We have seen this in the examples above.
The boot sector is not backed up on FAT16 partitions. Because FAT16 does not include a backup copy of critical data structures, they are susceptible to single point of failure issues, more so than other file systems.
There is no native file level security, compression or encryption available in the FAT16 file system.
Below is a table of Microsoft Operating systems and which file systems they can natively access.
Operating System Supports NTFS Supports FAT32 Supports FAT Max Partition
Windows XP Professional Yes Yes Yes 4GB
Windows XP Home Yes Yes Yes 4GB
Windows 2000 Professional Yes Yes Yes 4GB
Windows Millennium Edition No Yes Yes 2GB
Windows 98 and Second Edition No Yes Yes 2GB
Windows 95 OSR2 and OSR2.5 No Yes Yes 2GB
Windows NT4 Workstation Yes No Yes 4GB
Windows 95 Gold (Original Release) No No Yes 2GB
Windows NT3.5x Workstation Yes No Yes 4GB
MS-DOS (versions 3.3 and higher) No No Yes * see below