This article was previously published under Q118335
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Microsoft MS-DOS versions 4.0 and later allow FDISK to partition harddisks up to 4 gigabytes (GB) in size. However, the MS-DOS file allocationtable (FAT) file system can support only 2 GB per partition. Because ofthis fact, a hard disk between 2 and 4 GB in size must be broken downinto multiple partitions, each of which does not exceed 2 GB.
NOTE: Windows 95 OEM Service Release version 2 and later support driveslarger than 2 GB using the FAT32 file system. For more information aboutthe FAT32 file system, please see the following article in the MicrosoftKnowledge Base:
ARTICLE-ID: 154997 TITLE : Description of the FAT32 File System
The 2-GB partition limit is imposed by the maximum number of clusters andthe largest cluster size supported by the FAT file system. The FAT filesystem is limited to 65,525 clusters. The size of a cluster must be apower of 2 and less than 65,536 bytes--this results in a maximum clustersize 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 BIOSAPIs, which have a 1024-cylinder limitation, in order for FDISK topartition the hard disk.
Because 32K per cluster can waste valuable hard disk space, the FAT filesystem is not always the best hard disk management scheme. MicrosoftWindows NT uses the NT File System (NTFS), which uses a differentfile/cluster scheme. Microsoft OS/2 version 1.3 offered HPFS, which alsouses a more conservative method of allocating disk resources.
NOTE: Microsoft Windows NT also supports FAT drives. Windows NT 3.51supports FAT drives up to 4 GB in size. FAT drives from 2 GB to 4 GB insize are not supported by MS-DOS or Windows. In other words, if you wishto have a FAT drive accessible from MS-DOS or Windows 95/98 and WindowsNT, your FAT drive should be no larger than 2 GB. If you will be accessingthe FAT drive from only Windows NT, then the drive can be 2 GB to 4 GB insize.
For additional information about MS-DOS and Windows drive size andpartition limits, please see the following articles in the MicrosoftKnowledge Base:
ARTICLE-ID: 67321 TITLE : FAT Type and Cluster Size Depends on Logical Drive Size
ARTICLE-ID: 69912 TITLE : MS-DOS Partitioning Summary