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Limitations of FAT32 File System

August 24th, 2009

FAT32 File System The following limitations exist using the FAT32 file system with Windows operating systems:

  • Clusters cannot be 64 kilobytes (KB) or larger. If clusters were 64 KB or larger, some programs (such as Setup programs) might calculate disk space incorrectly.
  • A volume must contain at least 65,527 clusters to use the FAT32 file system. You cannot increase the cluster size on a volume using the FAT32 file system so that it ends up with less than 65,527 clusters.
  • The maximum possible number of clusters on a volume using the FAT32 file system is 268,435,445. With a maximum of 32 KB per cluster with space for the file allocation table (FAT), this equates to a maximum disk size of approximately 8 terabytes (TB).
  • The ScanDisk tool included with Microsoft Windows 95 and Microsoft Windows 98 is a 16-bit program. Such programs have a single memory block maximum allocation size of 16 MB less 64 KB. Therefore, The Windows 95 or Windows 98 ScanDisk tool cannot process volumes using the FAT32 file system that have a FAT larger than 16 MB less 64 KB in size. A FAT entry on a volume using the FAT32 file system uses 4 bytes, so ScanDisk cannot process the FAT on a volume using the FAT32 file system that defines more than 4,177,920 clusters (including the two reserved clusters). Including the FATs themselves, this works out, at the maximum of 32 KB per cluster, to a volume size of 127.53 gigabytes (GB).
  • You cannot decrease the cluster size on a volume using the FAT32 file system so that the FAT ends up larger than 16 MB less 64 KB in size.
  • You cannot format a volume larger than 32 GB in size using the FAT32 file system in Windows 2000. The Windows 2000 FastFAT driver can mount and support volumes larger than 32 GB that use the FAT32 file system (subject to the other limits), but you cannot create one using the Format tool. This behavior is by design. If you need to create a volume larger than 32 GB, use the NTFS file system instead.

NOTE: When attempting to format a FAT32 partition larger than 32 GB, the format fails near the end of the process with the following error:

Logical Disk Manager: Volume size too big.

FAT32 offers the best compatibility for PC and Mac operating systems, including cross-platform compatibility with the MAC OS X. However, FAT32 has inherent limitations in regards to file size, partition size, and performance.

Limitations under Windows, Mac OS 9, and Mac X:

  • A file cannot be transferred to a FAT32 partition if the file is larger than 4GB.
  • Apple’s Time Machine backup utility will not store data on FAT32 partitions.

Limitations under Windows 2000/XP/Vista:

  • A FAT32 partition cannot be created that is larger than 32GB.
  • A file cannot be transferred to a FAT32 partition if the file is larger than 4GB.
  • FAT32 file system performs more slowly than NTFS (Windows) or Mac OS Extended (HFS Plus, Mac).
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