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Benefits of the exFAT File System

The exFAT file system was developed to overcome a few inefficiencies of the FAT-32 file system. exFAT is in fact quite similar to FAT-32. Major changes are:

• No Short File Names. exFAT files have only one name, which is encoded as Unicode on disk and can have up to 255 characters.
• 64-Bit File Size. exFAT overcomes the 4G file size limitation of FAT.
• Cluster Sizes up to 32M. exFAT overcomes the 64k cluster size limit of FAT which makes exFAT suitable for much larger disks than FAT.
• Only One FAT. exFAT volumes do not maintain two FATs, but only one, reducing the space and processing overhead.
• Free Cluster Bitmap. In addition to the FAT (File Allocation Table) also used on FAT-32, exFAT also uses a cluster bitmap to keep track of allocated and free clusters. The bitmap dramatically reduces the number of required read/write operations of the FAT.
• Contiguous File Optimization. Contiguous files get special treatment by exFAT, making reading and writing such files faster. Typically, more than 90% of all files on a disk are contiguous.
• File Name Hashes. The use of file name hashes and the lack of short file names makes searching in directories or opening files significantly faster than on FAT volumes.

The improvements listed above are particularly significant on large volumes or slow disks (e.g., large USB sticks on a USB 1.1 port) or on systems with a weak CPU. Microsoft Windows refuses to format disks above 32G with FAT to avoid the performance problems FAT can have on large disks.

The exFAT File System Structure

API Differences Between FAT and exFAT