What is EXFat and how is it different from FAT32?

Louise Booth October 17, 2012
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I use a Macbook and Windows and I need to format two 16GB USB drives. They need to be compatible with Mac and different versions of Windows, so I was considering FAT32.

Someone mentioned EXFat, but I don’t know much about it or the difference between it and FAT32. Which is better between the two?

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  1. Robert
    October 19, 2012 at 12:22 am

    You can start with my exfat blog at rshullic.wordpress.com
    Exfat is supported with windows XP SP2 and SP3 with a KB patch. With vista with SP1 and SP2, and windows 7 out of the box.
    I hear compatibility with the latest version of macs, but not all macs.
    So the first and important issue is cross system compatibility. You should test by formatting one USB stick, and plugging in each machine and see if the machine recognizes the file system, and that you can create, delete, and change files on the stick, going back and forth a couple of times between systems. This way you can check to see if a file created by Mac can be read by windows, and vise versa.

    For a 16gb stick, the only advantage you would probably get is being able to write a single file that is greater than 4gb. File performance isn't going to make much of a difference. You may be better with FAT32. When you start getting into larger external drives, then exfat may ave an advantage, especially in performance.
    Another issue, which you won't see with 16gb is that Microsoft won't let you format storage media larger than 32gb unless it is NTFS, or if supported, exFAT. That doesn't app,y here because your median is smaller.

  2. Boni Oloff
    October 18, 2012 at 12:15 pm

    Exfat32 let you store larger files..

  3. Harshit Jain
    October 18, 2012 at 10:42 am

    FAT32 issues and problems -

    By default windows systems can only format a drive up to 32 GB. Additional software works around this issue. When formatted at these bigger sizes, FAT32 becomes increasingly inefficient.
    The maximum file size on a FAT32 formatted drive is around 4 GB. With DVD and high resolution DVD formats now available, this limit is commonly reached.
    Dealing with fragmentation and free disk space calculations can become painfully resource intensive in large FAT32 systems.
    A FAT32 directory can have 65,536 directory entries. Each file or subdirectory can take up multiple entries; therefore, FAT32 directories are limited with how many files it can hold.

    exFAT Advantages
    1 File size limit is now 16 exabytes.
    2 Format size limits and files per directory limits are practically eliminated.
    3 Like HPFS, exFAT uses free space bitmaps to reduce fragmentation and free space allocation/detection issues.
    4 Like HTFS, permission systems should be able to be attached through an access control list (ACL). It is unclear if or when Vista will include this feature, however.

    In conclusion, FAT32 is a simple system. The simplicity of FAT32 causes it to lose efficiency at large sizes but allows it to run with less resources. The complexity of NTFS increases features but requires more memory and processing power. exFAT is an improved and more complex system than FAT but is designed for flash drives only.

    Source: http://www.tech-recipes.com/rx/2801/exfat_versus_fat32_versus_ntfs/

    • Robert
      October 19, 2012 at 12:39 am

      The current desktop/server version of exFAT is 1.0, so TexFAT, and ACL is not yet supported. I clarify this because the windows CE version has these features.
      File directories size AE not completely unlimited, the root directory is, but subdirectories have a max size of 256mib, and the 32 byte directory entries requires at least 3 and up to 19 entries per file.
      FAT32 has 2 FAT tables, so there is some recovery if a FAT becomes toast, exFAT only has ONE FAT table, and you don't get recovery unless you use Transactional ExFAT and then you get 2 FAT tables, but there is no desktop/server support today.

  4. Keefe Kingston
    October 18, 2012 at 12:34 am

    EXFat is just an extended version of the FAT format. Unlike FAT, and FAT32, it can support files as large as 16 Exbibytes, and can support disk sizes up to 64 Zebibytes. FAT32 only supports files as large as 4GBs, and drives as large as 2TBs. If you plan on storing files larger then 4GBs on it, then you should use EXFat on your USB drive, as it will then be able to support files that large. As long as you have MacOSX Snow Leopard 10.6.5 or greater on your Mac, then you'll be able to use your drive with both computers. However, if your not going to be storing files that large on your USB drive, then just stick with FAT32. Hope this helps a bit!

    • salim benhouhou
      October 18, 2012 at 12:31 pm

      thank you Keefe for the explanation

      • Keefe Kingston
        October 18, 2012 at 5:47 pm

        No problem! ^^

    • Robert
      October 19, 2012 at 12:32 am

      Half of this information is actually wrong, but the key parts are correct. Aside from the 4gb restriction, the other numbers are wrong. In the current Microsoft specification for exFAT, because of the 32 bit fat size entries, you could never get a file greater thn 128pib, although the value is less than 128pib. The 64zib is a bogus number, even if you had a device that big and formatted, the fie system can never be much larger than 128pib. The 64zib is theoretical than the current spec can't actually support. It was derived by taking a 4k sector size and assuming a maximum number of sectors based on a 64 bit number (I.e. 2^64 times 2^12 = 2^76. 2^70 is a ZIB, and 2^6 is 64, thus 2^76 is 64ZIB)

      Since the file system can never exceed 128PIB, a single file can't be that big either. You can't have a file outside the cluster space. So the 16EIB is also wrong, people use that value because the file size goes into a 64 bit number, but jut because the field supports 2^64 does not mean you can get a file that big.

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