Understanding File System Options Page 2

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FAT32 File Systems

FAT32 is supported by the Windows Server 2003 family of operating systems as well as a number of the newer Microsoft operating systems. FAT32 was first introduced with Microsoft Windows 95 OSR2. The major differences between FAT and FAT32 are volume and cluster sizes and that only Microsoft operating systems can natively access FAT32.

The FAT32 file system supports drives up to 2 TB in size (in theory). Because it uses space more efficiently, FAT32 uses smaller clusters (i.e., 4,096 byte clusters for drives up to 8 GB in size), resulting in more efficient use of disk space compared to large FAT16 drives.

FAT32 File System Cluster Sizes
Partition Size
Cluster Size
0 MB - less than 260 MB 512 bytes
260 MB - 8 GB 4,096 bytes
8 GB - 16 GB 8,192 bytes
16 GB - 32 GB 16,384 bytes
32 GB - 2 TB 32,768 bytes

The 50 files mentioned in the FAT16 section, all 1,024 bytes (1KB) in actual size, would consume only 409,600 bytes on a 16 GB partition formatted with FAT16, and only 204,800 bytes on a 8 GB partition. As you can see, however, we now run into the issue with FAT32 drives with 80 GB and 100 GB partitions that we did a few years ago under FAT16 -- wasted space. Those same 50 files would use 819,200 bytes on either of the two large drives previously mentioned.

While the FAT32 file system can support drives up to a standard theoretical size of 2 TB, (it "can" be jury-rigged under Windows Millennium Edition to support partitions of up to 8 TB) Windows Server 2003, Windows 2000 Server or Professional, and Windows XP Professional and Home Edition cannot FORMAT a volume larger than 32 GB using their native FAT32 file system.

The FastFAT driver can mount and support volumes larger than 32 GB that use the FAT32 file system, such as those created locally by Windows 98 or ME in dual boot configuration (subject to a variety of limitations), but you cannot CREATE one using the Format tool from within Windows Server 2003, Windows 2000 Server or Professional, or Windows XP Home or Professional. If you attempt to format a FAT32 partition larger than 32 GB, the format fails near the end of the process with the following error message: Logical Disk Manager: Volume size too big.

In summary, the advantages of the FAT32 file system are:

  • FAT32 allocates disk space much more efficiently than FAT16.
  • The root folder on a FAT32 drive is not restricted in the number of entries in the root folder as was FAT16.
  • FAT32 is a more robust file system than FAT16. FAT32 can 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.

And the disadvantages are:

  • FAT32 volumes are not accessible from operating systems other than certain ones from Microsoft.
  • FAT32 partition sizes are limited to 32 GB in size using the native FAT32 file system format tools under Windows Server 2003, Windows 2000 and Windows XP.
  • No native file level security, compression or encryption available in the FAT32 file system.

Below is a list of Microsoft operating systems indicating which support native access to the FAT32 file system.

Operating System
Windows Server 2003 Yes
Windows XP Professional Yes
Windows XP Home Yes
Windows 2000 Professional Yes
Windows Millennium Edition Yes
Windows 98 and Second Edition Yes
Windows 95 OSR2 and OSR2.5 Yes
Windows NT4 Workstation No
Windows 95 Gold (Original Release) No
Windows NT3.5x Workstation No
MS-DOS (versions 3.3 and higher) No

Answers to a variety of common questions about the FAT32 File System, can be found on Q253774.

More information on the Limitations of FAT32 File System on Windows 98, ME and 2000, you can look up Q184006. You can find the information for the limitations of the FAT32 File System in Windows XP information at Q314463. Maximum partition sizes, both practical and theoretical is listed here as well.

Volumes from 33 MB to 2 TB can be accessed under Windows Server 2003; however, the maximum size that can be formatted under is 32 GB. The maximum single file size on a FAT32 partition is 4 GB, regardless of the size of the partition.

This article was originally published on Jul 24, 2003
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