FAT or File Allocation Table is a computer file system architecture or hard drive format. It was originally designed in 1977 for use on floppy disks before being adapted for use on hard drives in the Microsoft DOS to Windows 9x variants. In modern operating systems FAT has been replaced as the hard drive format of choice in Windows by NTFS since Windows XP due to overall disk size limitations and maximum single file size limits that are not present in NTFS, however FAT is still widely used in removable media such as SD cards and USB thumb drive memory sticks.
Technipages Explains FAT
FAT defines a hard drive by splitting it into equal-sized blocks or clusters of memory and storing references to those allocated blocks in a table. There are four major variants: FAT, FAT12, FAT16 and FAT32, with the increasing number reflecting the increasing size of the table. FAT came with a number of drawbacks which were at first addressed by increasing the size of the table but eventually lead to FAT32 being superseded. FAT32 comes with a maximum file size limit for a single file of 4GiB.
Only one file can be allocated to each block (although it can run over multiple blocks) this means that for very small files end up taking up significantly more space than they actually require (with a 32KB block size and a 1KB file, 31KB’s are left unusable). It is possible to format the disk to use a smaller block size so less space is wasted but because there is a limited number of possible blocks this has the net effect of reducing the maximum possible size of the FAT formatted drive.
Fat32 is still relevant today especially for removable media and is supported in all operating systems but it is best suited to use in drives of 32 GB or less.
Common Uses of FAT
- The USB stick is formatted to FAT32.
- You should only use FAT for removable storage devices.
- My computer can read FAT32 formatted SD cards.
Common Misuses of FAT
- My hard drive is too FAT.