Friday, June 29, 2012

Why not exFAT?

Quote Wikipedia's exFAT page:
Microsoft has not released the official exFAT file system specification, and a restrictive license from Microsoft is required in order to make and distribute exFAT implementations. Microsoft also asserts patents on exFAT which make it impossible to re-implement its functionality in a compatible way without violating a large percentage of them.[11] This renders the implementation, distribution, and use of exFAT as a part of free or open-source operating systems or of commercial software, for which the vendors could not obtain a license from Microsoft, not only technically difficult, but legally impossible in countries that recognize United States software patents.
Team Epic's CWM does not, and will never support the exFAT filesystem for several reasons.
  • Legally Hazardous: Microsoft intentionally created exFAT to be legally hazardous and incompatible with software freedom and Open Source Software.
  • You Don't Need It: You can format your 64GB sdcard as FAT32.  While it is a bit inefficient in filesystem slack, FAT32 is compatible with every computer you could mount your storage on, including all versions of Windows, MacOS X and Linux.  exFAT can only be used with MacOS X 10.6+, which the majority of Mac users do not have.  The above Wikipedia page also suggests FAT32 might even have better I/O performance.
  • CM probably won't support it either: CM has not made any decision about exFAT, however given this legally hazardous situation it is unlikely to ever support exFAT.
How do I avoid exFAT?
  • Copy the data from your existing exFAT formatted sdcard into a folder on your computer.
  • Re-format to FAT32 using the phone's Storage menu.
    • Alternatively, try this utility that claims to format > 32GB disks on Windows to the FAT32 filesystem.  If this works for you please report your results so we can update this blog post.
  • Copy your data from your backup folder onto the sdcard after it is reformatted.


    1. I store the pictures and videos taken from my phone's camera onto the external SD card. If I format it to FAT32 will it limit the maximum size of the videos to 4GBs?

    2. Yes the 4gb file size is a limitation of the fat32 file system.

    3. Samsung Galaxy S3 reformats as exFAT, fortunately the FAT32format utility was able to change it and the phone reads the SD card still.

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    5. Used that Ridgecorp utility you posted and it worked perfectly in formatting my 64GB card in FAT32. Did not need admin rights either (unlike what the site says). Used it on a Team 64GB UHS1 MicroSDXC that Newegg frequently has for $30-35. Model TUSDX64GUHS03. Thanks for the heads up.

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