Mac OS X can't write to a hard drive with the NTFS format. It can, however, read it.

Why can't it write to it?

My basic understanding is that a file format dictates how is data stored and retrieved in a device. So, the key to working with a storage device is to know the rules for data storage and retrieval.

Since OS X is able to read devices with the NTFS format, obviously OS X knows such rules. What exactly stops OS X from following the necessary rules to write data to an NTFS device? It knows that it is NTFS (just do Get Info), so I see no reason why it can't do this.

  • Mac OS X can write to NTFS disks. There is a terminal command (I believe it is this: sudo echo "UUID=ENTER_UUID_HERE none ntfs rw,auto,nobrowse" >> /etc/fstab) that allows Mac to write. As to why Apple didn't enable it by default, I don't know. – PoisonNinja Mar 24 '14 at 23:13
  • Actually it can and it works well if you do as AnonymousAppDev wrote. – Max Ried Mar 24 '14 at 23:51

OS X can write to NTFS volumes. However, it's a hidden switch, and it's not supported. Use it at your own risk.

OS-level support for a file system is a major technical investment. It's not just about knowing the rules. There are fundamental differences between HFS+ and NTFS, such as characters supported in the name and maximum file size. When writing an OS, not to mention applications, it's very easy to make assumptions in your code that rely on the expected file system.

Reading a file from a different file system is significantly easier than writing a file to a different file system. In only reading a file, there is very little chance of data loss. In writing a file, it is imperative that the act of writing the file does not lose data (either in the file that you are writing, or other files on the disk).

Supporting another file system means that there is a massive expense to the OS development and test teams. If you take a look at this comparison of file systems, you can see many places where these two file systems differ. Without official support for NTFS, the safest assumption is that it hasn't been sufficiently tested and might not support all of the features of NTFS.

  • Great explanation! In some cases the interoperability is impossible: a caes sensitive file system where there exit files named a and A in the same directory can't be correctly managed on an OS which is case unsensitive (because this OS won't be able to deal with the difference between these 2 files). – dan Mar 25 '14 at 9:18

Perhaps if we parse the EULA we would gain insight. It obviously CAN once you type the cheat code. Chromebooks and Linux (most) can. All file systems are abstracted away from the base OS since well 25+ years ago, that is to say they are all operated via a plug-in (eg how can a DOS PC read NTFS? mount it as a SMB share and use the network drivers etc etc) So in summary there is no technical limitation, the limitation encountered is of a legal nature (define intentional rather than accidental). This is the Apple we all know, smartly dressed, impecable mannners, lite on small talk and holding those cards real close. The old Apple, the one that grabs you by the throat and screams halitosis perfumed deaththreats an inch from your eyeballs, that Apple has gone.

  • Do you have any evidence for this? I haven't found anything supporting this, it can read NTFS fine, AFAIK there's no legal restrictions that could be put in place anyways, and Apple's "image" doesn't seem at stake in any way here. – JMY1000 Nov 27 '17 at 3:14

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