Author Topic: Preparing cards to exFAT – Mac weirdness sorted!  (Read 470 times)


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Preparing cards to exFAT – Mac weirdness sorted!
« on: February 01, 2020, 03:46:30 PM »
Windows users can safely ignore this post! This is to help out with Mac-only weirdness.

If you are using the new card spanning and sd overclocking features from ilia and Danne you may find that formatting your cards to exFAT with larger allocation block sizes could improve the write speeds. Thanks to @70MM13 for alerting me to this option!

When formatted in exFAT from Mac's own Disk Utility, my SD Sandisk Extreme Pro 64G is given a default block size of 32768 bytes (0.3Mb).

Write speed was then tested on the Black Magic Speed tester, = 51

After formatting to exFAT with a block size of 16Mb, the write speed = 72

Your mileage may vary!

You can format the card to this spec by either doing it in Windows disk management, or use the Terminal in Mac:

Code: [Select]
sudo newfs_exfat -b 16777216 -v NameThePartition /dev/diskNumber
That's all great, but if you now try to mount an exFAT card on the Mac that has been formatted with anything larger than 1048576 bytes (1Mb), the partition will just not mount. No way. So you either need Windows running to empty the cards – which I started doing, but it's a pain. Then I found this project on GitHub:

I think it's based around FUSE and it works a treat! Anyone who has used MLVFS will be familiar with the concept. When commanded it will mount the custom exFAT cards on the Mac with ease! :)

I do:

Code: [Select]
cd exfat

sudo ./fuse/mount.exfat-fuse /dev/diskNumber /Users/Me/Desktop/mount

Note for when the installation and directions call for being a 'root' user. In Terminal you can start a root session by:

Code: [Select]
sudo -s
Be careful though – and type with care in this mode. This gives you super powers to destroy planet earth – and your Mac entirely!
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