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
TITLE : Description of the FAT32 File System
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
For additional information about MS-DOS and Windows drive size and
partition limits, please see the following articles in the Microsoft
TITLE : FAT Type and Cluster Size Depends on Logical Drive Size
TITLE : MS-DOS Partitioning Summary