Learn Windows XP Professional in 15 Minutes a Week: Implementing and Conducting Administration of Resources

by Jason Zandri

Welcome to this week's installment of Learn Windows XP Professional in 15 minutes a week, the sixth in the series. With this article I will begin focusing on the next section of material which centers on Implementing and Conducting Administration of Resources on Windows XP Professional, this one covering Windows XP Professional file systems.

Jason Zandri's latest article in the Learning Windows XP Professional in 15 Minutes a Week series focuses on implementing and conducting the administration of resources on Windows XP Professional and specifically covers Windows XP Professional file systems.

Implementing and Conducting Administration of Resources

File System Overview

To have a good understanding of how and why you can set up or deny access to data on a Windows XP Professional system, you need to have an underlying understanding of any native file security that may or may not be in place.

One place to start would be the file system the operating system is utilizing.

Windows XP Professional supports the three major computer files systems of File Allocation Table (commonly known as FAT or FAT16), FAT32 and NTFS.


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

[NOTES FROM THE FIELD] - There is no test requirement to memorize these tables, but 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.

The maximum FAT partition that can be created and accessed by the operating systems listed above is 2GB in most cases. 4GB FAT partitions can be created and properly accessed only under those operating systems specifically listed above. A dual boot NT family of operating system can create a 4GB FAT partition and a lower level OS such as Windows 98 may be able to see data on it, however, issues will arise when data access is attempted above the 2GB threshold that the OS normally uses.

For more information on the Maximum Partition Size Using the FAT16 File System in Windows XP, you can look up Q310561 at the Microsoft PSS webpage.

The "OSR" in "Windows 95 OSR2 and OSR2.5" stands for OEM Service Release.

The "OEM" in "OEM Service Release" stands for Original Equipment Manufacturer.

For more information on Accessing FAT16 Drives Larger Than 2 GB, or Maximum Partition Size Using FAT16 File System, feel free to follow the links I have provided to the Microsoft web site.

* There are some exceptions, but for the most part, DOS 3.3 and higher can access up to 2GB of single partition space, as outlined in Q67321 at the Microsoft PSS webpage. The MS-DOS Partitioning Summary (Q69912) names some exceptions and points out the fact that some earlier versions didn't support many of today's FAT16 standards.

The maximum single file size on a FAT16 partition is 2 GB, regardless of the fact that some OSes can have a 4GB partition.

This article was originally published on Jun 3, 2002
Page 1 of 5

Thanks for your registration, follow us on our social networks to keep up-to-date