Microsoft introduced the Extensible File Allocation Table or exFAT in 2006 as a file system optimized for flash memory such as USB flash drives and Secure Digital or SD cards. Originally a proprietary technology until Microsoft released its technical specification on 28 August 2019, it is now one of the most popular file systems used in removable storage mediums due to its advantages, especially its compatibility across different platforms.
Pros of Extensible FAT: Advantages of exFAT File System
Specific Advantages Over the FAT32 File System
The FAT32 file system provided notable advantages over the previous version of the File Allocation Table file system. However, it has notable drawbacks centered on limited maximum file size and maximum volume size that make it unideal as a storage solution for storing and transferring files larger than 4GB. Extensible FAT is fundamentally a derivative of FAT that includes improvements.
Compared to FAT32, which supports a maximum file size of 4GB and volume size of 32GB on Windows format, 2TB on other operating systems, and 16TB on certain theoretical applications, exFAT supports a maximum file size of 16 exabytes while storing file size references in eight bytes instead of four bytes. These characteristics make it ideal for storing large files, recording high-quality video, and formatting high-capacity flash memory devices. Note that the SD Association has adapted it as a default file system for the high-capacity SDXC cards.
Operating Systems and Platform Compatibility
Another advantage of exFAT, especially when compared to NTFS, the Extended File System, and Apple File System or APFS, is that it is seamlessly interoperable between different operating systems and platforms. Windows can read and write on storage mediums formatted based on this file format. The same is true for macOS, Linux distributions such as Debian and Ubuntu, Android, and the platforms used in several video gaming consoles and other consumer electronic devices, including digital media players and television sets.
The AFPS is limited to Apple devices running the macOS or the iOS and iPadOS operating systems. macOS can read storage mediums formatted based on NTFS, but it cannot write new data, thereby making these storage devices useless for transferring files between different operating systems or platforms. Furthermore, digital cameras, media players, and television sets would not be able to read storage mediums based on the NTFS file system.
Extensible FAT is essentially useful when working with different operating systems and large files. It is a suitable file system in situations in which NTFS does not provide a practical solution. Of course, it is important to reiterate the fact that it also supports a range of storage mediums to include hard disk drives, solid-state drives, and flash memory storage to include MultiMediaCard and Embedded MultiMediaCard or eMMC, and Universal Flash Storage.
Other Notable Features of exFAT File System
Similar to NTFS, Extensible FAT has a file and cluster pre-allocation feature, which pre-allocates disk space for a file by just marking arbitrary space on a disk. It also uses a cluster bitmap to keep track of allocated and free clusters. The bitmap significantly reduces the number or frequency of required read-write operations of the file system. Similar to other FAT file systems, its simple and lean structure, as well as power efficiency, make it suitable for embedded storage solutions.
There are also specific features that make it ideal for flash memory storage. One of such is boundary alignment for file system structures, which allows adjusting FAT offsets and cluster heap based on format-time, thereby enabling writing on as few flash blocks as possible to preserve the integrity of the entire flash memory. There is also an OEM Parameters field that is useful for recording the block size of an underlying storage, as well as the absence of journaling to maximize storage space and the longevity of flash memory by writing fewer data.
Cons of Extensible FAT: Disadvantages of exFAT File System
Absence of Journaling and Compression
A key disadvantage of exFAT, particularly when compared to NTFS and Extended FileSystem, including iext3 and ext4, is the absence of journaling. A journaling functionality is a specific system in which any changes to the files on the disk are tracked and recorded in a log or journal before they are actually performed or before these changes transpire.
Journaling works by allocating a special area or journal to record changes ahead of time. It essentially tracks changes that have not transpired in the main part of the file system by recording them in a data structure known as a journal. The absence of this capability in the File Allocation Table file systems makes them prone to errors due to system or crashes and power outages, while a particular storage medium is in operation. Mediums based on Extensible FAT are susceptible to data corruption or data losses due to interruptions.
None of the FAT file systems provide built-in compression features. Files stored on storage mediums based on either one of these systems are usually larger than similar files stored on mediums formatted based on New Technology File System. Small files will also take up more storage space because clusters are larger than NTFS.
Other Notable Drawbacks of this File System
NTFS remains the ideal file system for use in Windows since the introduction of Windows XP, while Apple uses its proprietary APFS file system. Note that exFAT is not as compatible as FAT32 when it comes to cross-platform applications or working across different operating system environments. For example, although it is compatible with Linux distributions, additional software is needed to make it readable and writable.
This file system also lacks advanced features built into NTFS. For example, similar to FAT32, it does not have the ability to protect and encrypt files. Note that built-in read-only and encryption capabilities are standard features in Windows operating system. The specific file allocation table and the file allocations themselves are not readily ideal for multi-user environments, thereby making it prone to file fragmentation.