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Microsoft Knowledge Base Article - 118335
Maximum Partition Size Using FAT16 File System
The information in this article applies to:
- Microsoft Windows Millennium Edition
- Microsoft Windows 98 Second Edition
- Microsoft Windows 98
- Microsoft Windows 95
- Microsoft MS-DOS operating system
This article was previously published under Q118335
SUMMARY
Microsoft MS-DOS versions 4.0 and later allow FDISK to partition hard disks up to 4 gigabytes (GB) in size.
However, the MS-DOS file allocation table (FAT) file system can support only 2 GB per partition. Because of this
fact, a hard disk between 2 and 4 GB in size must be broken down into multiple partitions, each of which does not
exceed 2 GB.
NOTE: Windows 95 OEM Service Release version 2 and later support drives larger than 2 GB using the FAT32 file system.
For more information about the FAT32 file system, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: 154997
TITLE : Description of the FAT32 File System
MORE INFORMATION
The 2-GB partition limit is imposed by the maximum number of clusters and the largest cluster size supported
by the FAT file system. The FAT file system is limited to 65,525 clusters. The size of a cluster must be a power
of 2 and less than 65,536 bytes--this results in a maximum cluster size of 32,768 bytes (32K). Multiplying the
maximum number of clusters (65,525) by the maximum cluster size (32,768) equals 2 GB.
Note that the hard disk drive must be supported by the computer's ROM BIOS APIs, which have a 1024-cylinder limitation,
in order for FDISK to partition the hard disk.
Because 32K per cluster can waste valuable hard disk space, the FAT file system is not always the best hard disk
management scheme. Microsoft Windows NT uses the NT File System (NTFS), which uses a different file/cluster scheme.
Microsoft OS/2 version 1.3 offered HPFS, which also uses a more conservative method of allocating disk resources.
NOTE: Microsoft Windows NT also supports FAT drives. Windows NT 3.51 supports FAT drives up to 4 GB in size. FAT
drives from 2 GB to 4 GB in size are not supported by MS-DOS or Windows. In other words, if you wish to have a
FAT drive accessible from MS-DOS or Windows 95/98 and Windows NT, your FAT drive should be no larger than 2 GB.
If you will be accessing the FAT drive from only Windows NT, then the drive can be 2 GB to 4 GB in size. For additional
information, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: 127851
TITLE : Problems Accessing Windows FAT Drives Larger than 2 GB
For additional information about MS-DOS and Windows drive size and partition limits, please see the following articles
in the Microsoft Knowledge Base:
ARTICLE-ID: 67321
TITLE : FAT Type and Cluster Size Depends on Logical Drive Size
ARTICLE-ID: 69912
TITLE : MS-DOS Partitioning Summary
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Last Reviewed:
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12/28/2001 |
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Keywords:
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kbHardware kbinfo kbsetup KB118335 |
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Microsoft Knowledge Base Article - 153550
Hard Disk Limited to 8-GB Partition
The information in this article applies to:
- Microsoft Windows Millennium Edition
- Microsoft Windows 98 Second Edition
- Microsoft Windows 98
- Microsoft Windows 95
This article was previously published under Q153550
SYMPTOMS
When you try to partition a drive that is larger than 8 gigabytes (GB) in size, the maximum partition size may
be 8 GB.
CAUSE
This behavior can occur if the hard disk controller does not fully support the interrupt 13 extensions. This
information applies to both IDE and SCSI hard disk drives.
RESOLUTION
Contact the drive controller's manufacturer for information about a possible BIOS upgrade to a version of the
BIOS that fully supports interrupt 13 extensions.
MORE INFORMATION
In order for a hard disk that is larger than 8 GB and uses the FAT32 file system to be fully addressed, it must
support interrupt 13 extensions. Io.sys tests for the presence of interrupt 13 extensions. If interrupt 13 extensions
are not detected, the default CHS LBA limit of 7.9 GB is used.
To determine whether your BIOS supports interrupt 13 extensions, please refer to your computer's documentation
or consult your computer's manufacturer.
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Last Reviewed:
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7/27/2001 |
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Keywords:
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kbDiskMemory kbFAQ kbHardware kbprb KB153550 |
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Microsoft Knowledge Base Article - 154997
Description of the FAT32 File System
The information in this article applies to:
- Microsoft Windows Millennium Edition
- Microsoft Windows 98 Second Edition
- Microsoft Windows 98
- Microsoft Windows 95 OEM Service Release 2
- Microsoft Windows 95 OEM Service Release 2.1
- Microsoft Windows 95 OEM Service Release 2.5
This article was previously published under Q154997
NOTE: This article is for informational use only. It does not contain any troubleshooting information.
If you are searching for troubleshooting information that is not mentioned in this article, search the Microsoft
Knowledge Base again by using keywords that are listed in the following Microsoft Knowledge Base article:
242450 How to Query
the Microsoft Knowledge Base Using Keywords
SUMMARY
This article describes the FAT32 file system that is included with Windows 95 OEM Service Release 2 (OSR2),
Windows 98, and Windows Millennium Edition (Me).
MORE INFORMATION
Windows 95 OSR2, Windows 98, and Windows Me include an updated version of the FAT file system. This updated
version is called FAT32. The FAT32 file system allows for a default cluster size as small as 4 KB, and includes
support for EIDE hard disk sizes larger than 2 gigabytes (GB).
NOTE: Microsoft Windows NT 4.0 does not support the FAT32 file system. For additional information
about supported file systems in Windows NT 4.0, click the article number below to view the article in the Microsoft
Knowledge Base:
100108 Overview
of FAT, HPFS, and NTFS File Systems
FAT32 Features
FAT32 provides the following enhancements over previous implementations of the FAT file system:
- FAT32 supports drives up to 2 terabytes in size.
NOTE: Microsoft Windows 2000 only supports FAT32 partitions up to a size of 32 GB.
- FAT32 uses space more efficiently. FAT32 uses smaller clusters (that is, 4-KB clusters for drives up to 8 GB
in size), resulting in 10 to 15 percent more efficient use of disk space relative to large FAT or FAT16 drives.
- FAT32 is more robust. FAT32 can relocate the root folder and use the backup copy of the file allocation table
instead of the default copy. In addition, the boot record on FAT32 drives is expanded to include a backup copy
of critical data structures. Therefore, FAT32 drives are less susceptible to a single point of failure than existing
FAT16 drives.
- FAT32 is more flexible. The root folder on a FAT32 drive is an ordinary cluster chain, so it can be located
anywhere on the drive. The previous limitations on the number of root folder entries no longer exist. In addition,
file allocation table mirroring can be disabled, allowing a copy of the file allocation table other than the first
one to be active. These features allow for dynamic resizing of FAT32 partitions. Note, however, that although the
FAT32 design allows for this capability, it will not be implemented by Microsoft in the initial release.
FAT32 Compatibility Considerations
To maintain the greatest compatibility possible with existing programs, networks, and device drivers, FAT32
was implemented with as little change as possible to the existing Windows architecture, internal data structures,
Application Programming Interfaces (APIs), and on-disk format. However, because 4 bytes are now required to store
cluster values, many internal and on-disk data structures and published APIs have been revised or expanded. In
some cases, existing APIs will not work on FAT32 drives. Most programs will be unaffected by these changes. Existing
tools and drivers should continue to work on FAT32 drives. However, MS-DOS block device drivers (for example, Aspidisk.sys)
and disk tools will need to be revised to support FAT32 drives.
All of the Microsoft bundled disk tools (Format, Fdisk, Defrag, and MS-DOS- based and Windows-based ScanDisk) have
been revised to work with FAT32. In addition, Microsoft is working with leading device driver and disk tool manufacturers
to support them in revising their products to support FAT32.
NOTE: A FAT32 volume cannot be compressed by using Microsoft DriveSpace or DriveSpace 3.
FAT32 Performance
Converting to the FAT32 file system is one of the biggest performance enhancements you can make to your Windows
98-based computer.
Dual-Boot Computers
At this time, Windows 95 OSR2, Windows 98, Windows 2000, and Windows Me are the only Microsoft operating systems
that can access FAT32 volumes. MS-DOS, the original version of Windows 95, and Windows NT 4.0 do not recognize
FAT32 partitions, and are unable to boot from a FAT32 volume. Also, FAT32 volumes cannot be accessed properly if
the computer is started by using another operating system (for example, a Windows 95 or MS-DOS boot disk).
Windows 95 OSR2 and Windows 98 can be started in Real mode (for example, to run a game) and can use FAT32 volumes.
Creating FAT32 Drives
In Windows 95 OSR2, Windows 98, and Windows Me, if you run the Fdisk tool on a hard disk that is over 512 megabytes
(MB) in size, Fdisk prompts you whether or not to enable large disk support. If you answer "Yes" (enabling
large disk support), any partition you create that is larger than 512 MB is marked as a FAT32 partition.
Windows 98 and Windows Me also includes a FAT32 conversion tool that you can use to convert an existing drive to
the FAT32 file system. To use the conversion tool, follow these steps:
- Click Start, point to Programs, point to Accessories, point
to System Tools, and then click Drive Converter (FAT32).
- Click Next.
- Click the drive that you want to convert to the FAT32 file system, and then click Next.
- Follow the instructions on the screen.
Support Boundaries
Microsoft will support the functionality of the FAT32 file system for error-free reading, and saving of files
either in Real mode or Protect mode. Microsoft supports the Real-mode and Protected-mode tools that are included
with Windows 95.
For legacy (older) programs that cannot be installed on a FAT32 volume, or do not properly save files or read them,
you must contact the manufacturer of the software package.
NOTE: Although the FAT32 file system supports hard disks up to 2 terabytes in size, some hard
disks may not be able to contain bootable partitions that are larger than 7.8 GB because of limitations in your
computer's basic input/output system (BIOS) INT13 interface. Please contact your hardware manufacturer to determine
if your computer's BIOS supports the updated INT13 extensions. For additional information about Windows 95 OSR2,
click the article number below to view the article in the Microsoft Knowledge Base:
155003 Desription
of Windows 95 OEM Service Release 2
For additional information about FAT32, click the article number below to view the article in the Microsoft Knowledge
Base:
253774 Common Questions
About the FAT32 File System
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Last Reviewed:
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2/22/2002 |
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Keywords:
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dtssb kbinfo KB154997 |
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