Choosing filesystem for external HDD under OS X

OS X diskDid you get a new Mac and you need to format your external HDD? Many computer beginners are confused by something “strange” – filesystem. In this post I won’t explain what is filesystem, I will just notice that every disk must have some. Here I will teach you about most common filesystems you can meet on OS X operating system. Don’t forget, formating your disk will erase all data!

It’s very important to choose right filesystem. Each got it’s own pros and cons. Now we will look at most common filesystems you can meet on OS X operating system:

  • OS X Extended (Journaled) with option for Case-sensitive and Encrypted
  • MS-DOS (FAT)
  • ExFAT

OS X Extended (Journaled):

Default filesystem for OS X. It’s support for other operating systems is poor, so I can recommend this filesystem for HDD if you only work with Macs or on your personal Mac. And whatabout that two other options? Case-sensitive means, that system recognizes capitalized characters, so “Raynor” is not same as “raynor”. Default is non-Case-sensitive, so “Raynor” and “raynor” means same. I strongly recommend to use default non-Case-sensitive, because some apps and games have problem to run on it, including Adobe products and Steam. Last option “Encrypted” is more safe option for your data on external HDD, but you will experience slower performance and some services may not work. You can combine “Case-sensitive” and “Encrypted”:

  • OS X Extended (Journaled)
  • OS X Extended (Case-sensitive, Journaled)
  • OS X Extended (Journaled, Encrypted)
  • OS X Extended (Case-sensitive, Journaled, Encrypted)

Best option for most users is “OS X Extended (Journaled)”.


This filesystem works well on Macs and PCs, you can both read and write, but again we got 4 GB limit per file. For example, DVD capacity is 4.7 GB, CD is 0.7 GB (700 MB). If you need to store file bigger than 4 GB on FAT32, here are two workarounds. First is split file on smaller ones with special program. If you split 6 GB file into three 2 GB, you can store them on FAT32. Second one is try to compress it – I’m sure you did hear about WinRAR or WinZip. If you got, for example, 4.5 GB file, you can try to compress in into ZIP/RAR file. Maybe you will be lucky and get file under 4 GB. You can combine these workarounds too. But don’t forget, you won’t be able to open files on FAT32, only store it, because when you merge or decompress file, it will be over 4 GB again.

And last one – exFAT:

exFAT is most universal from these filesystems. Disks with exFAT filesystem can be both read and written by Macs and most PCs and devices and all without annoying 4 GB limit on FAT32. If you need to share files on external HDD with Windows/Linux computers and your Mac, exFAT is best solution. From modern Windows operating system is just one problem – Windows XP need Service Pack 2 or 3 and “WindowsXP-KB955704-x86-ENU.exe” installed.

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