Learn Windows XP Professional: Administration of Resources (Page 2) Page 2


FAT32 is supported by Windows XP Professional, as well as a number of the newer Microsoft Operating systems. FAT32 was first introduced with Microsoft Windows 95 OSR2 and the major differences between FAT and FAT32 are volume and cluster sizes for the most part as well as the fact that only Microsoft Operating systems can natively access FAT32.  

The FAT32 file system can support drives up to 2 terabytes in size (in theory), and because it uses space more efficiently, FAT32 uses smaller clusters (that is, 4,096 byte clusters for drives up to 8 GB in size), resulting in more efficient use of disk space relative to large FAT16 drives.

FAT32 File System Cluster Sizes

Partition Size   Cluster Size
0M to less than 260MB 512 bytes
260MB through 8GB 4,096 bytes
8GB through 16GB 8,192 bytes
16GB through 32GB 16,384 bytes
32GB through 2TB 32,768 bytes

The 50 files I mentioned in the FAT16 section, all 1024 bytes (1KB) in actual size, would use up only 409,600 bytes on a 16GB partition formatted with FAT16 and only 204,800 bytes on a 8GB partition. As you can see however, we are now running into the issue with FAT32 drives with 80GB and 100GB 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 I mentioned. There's a Windows 2000 Professional and XP Professional catch, however.

While the FAT32 file system can support drives up to a standard theoretical size of 2 terabytes, (it "can" be jury-rigged under Windows Millennium Edition to support partitions of up to 8 TB Windows 2000 Professional and XP Professional cannot FORMAT a volume larger than 32 GB in size 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 other limits listed here for Windows 98, ME and 2000 and here for Windows XP), but you cannot CREATE one using the Format tool from within either Windows 2000 Professional or XP 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 was. 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.
Just as there were disadvantages to the FAT16 file system, so there are in FAT32 as well:

  • FAT32 volumes are not accessible from any other operating systems other than certain Microsoft ones.

  • FAT32 partition sizes are limited to 32GB in size using the native FAT32 file system format tools under Windows 2000 and Windows XP. (The maximum size is 127.5 GB practical and 2TB standard theoretical.

  • There is no native file level security, compression or encryption available in the FAT32 file system.

Below is a table of Microsoft Operating systems which support native access to the FAT32 file system.

Operating System  Supports FAT32 
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

[NOTES FROM THE FIELD] - There is no test requirement to memorize the FAT32 tables either, but again, it's good to understand the "how and why" of it. Also, it is never a "best practice" to dual boot any workstation or server that has sensitive data on it with any file system installed that cannot secure those files or any operating system that threatens that security. This would include the FAT32 file system.

For answers to some common questions about the FAT32 File System, you can look up Q253774 at the Microsoft PSS webpage.

For more information on the Limitations of FAT32 File System on Windows 98, ME and 2000, you can look up Q184006 at the Microsoft PSS webpage. You can find the information for the limitations of the FAT32 File System in Windows XP information available at Q314463. You will also find the maximum partition sizes, both practical and theoretical listed there as well.

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 Jun 3, 2002

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