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Teach your Mac a new trick. If you’ve plugged a USB stick or external hard drive only to find out it’s “Read Only”, don’t panic: there’s a reason for this, and there’s a way to fix it.

Different operating systems organize files in different ways From FAT To NTFS To ZFS: File Systems Demystified [MakeUseOf Explains] From FAT To NTFS To ZFS: File Systems Demystified [MakeUseOf Explains] Do you really know what your hard drive does whenever you read a file from it or write one to it? Our hard drives can now store massive amounts of data, and that massive space... Read More . Mac OS X, for example, uses a filing structure called HFS+ – modern versions of Windows use NTFS. These different ways of physically arranging files on a drive confuse operating systems that aren’t used to them. Windows computers cannot open HFS drives, for example. Macs can read NTFS drives, but not write to them.

Why is this? It’s complicated, but the answer basically boils down to patents. For Windows computers to read HFS drives, Microsoft would have to pay Apple… something they won’t do. Enabling Apple computers to write to NTFS drives would involve similar expense. It’s a little more complex than this, but the basic result is that your Mac cannot write to NTFS drives.

For now.

read only external hard drive mac

Like I said: don’t panic. You can fix this. You’ve got three main options:

  1. Reformat your USB drive with FAT. This format can be read by Macs and Windows PCs alike. This is probably the simplest method, but there’s one drawback: reformatting requires deleting everything on the drive, so back it up first. On your Mac you can use Disk Utility to reformat; in Windows you need to right-click the drive, then click Format. Be sure to select FAT32 as your filesystem.
  2. Turning on OS X’s built-in support for writing to NTFS. Doing so requires some confidence, as the process isn’t entirely user-friendly – and needs to be re-done for every NTFS drive you wish to mount. Check out this blog post by Prateek V. Joshi for more information.
  3. Install software that automatically allows you to read every NTFS drive. This is the simplest option, and it’s what I’m going to outline below.

Below I’ll outline the easy-to-use paid options and a slightly-more-complex free alternative.

Using Commercial Software

Let’s go over the easiest way to solve this problem first: commercial software. Paragon NTFS for Mac is easy to install, and enables NTFS writing almost instantly. Once it’s installed you won’t even notice it’s there, save for a single entry in your OS X preferences window.

read only external hard drive

Read more about Paragon NTFS Paragon NTFS For Mac OS X Review Paragon NTFS For Mac OS X Review One of the drawbacks when switching from Windows to Mac is the lack of native NTFS support. You can read from NTFS volumes with no problems, but writing is another story. Luckily software like Paragon... Read More , if you’re interested. The software isn’t expensive – it runs you $20 – and it’s one of the first such programs out there to officially support Mountain Lion (10.8).

Paragon isn’t the only paid software for the job out there – Tuxera (which maintains the free solution outlined below) offers similar software for 25 euros ($31). Check out for more information.

NTFS-3G: The Free Alternative

Prefer a free alternative? NTFS-3G is an open source driver used by many Linux users to read and write to NTFS drives, and and you can use it on your Mac too. It’s just a matter of knowing where to find it – and the answer is this blog post from 2010. It includes the most recent download for NTFS-3G for Mac.

The installation process is easy, but pay attention during this part:

read only external hard drive

It’s probably safest to go without the caching, but there are performance advantages to using it. It’s up to you.

Of course, if you’re using Lion or Mountain Lion (and you probably are), you’ll notice this software doesn’t work. You didn’t think it would be that easy, did you?

Fixing NTFS-3G for Mountain Lion

Simply installing NTFS-3G isn’t enough if you use Mountain Lion or Lion – the free software hasn’t been updated for these releases, and doesn’t work. You’ll see warnings at boot, and none of your NTFS drives will mount.

Again: don’t panic. This blog post by Julian Xhokaxhiu has all the answers. To summarize, you need to:

  1. Install MacFUSE.
  2. Install the Fuse error fix package
  3. Install Install OS X Fuse. Be sure to check Emulate MacFUSE during installation:

read only external hard drive mac

Do all of this and you should be able to mount your NTFS drives without any problems – and write to them. Enjoy!


Incompatibilities between Macs and Windows PCs used to be a lot worse than today – the two computers had hardly any file formats in common. Those days are largely past, but a few reminders remain. NTFS hiccups are one of them.

As you can tell, though, there are ways around most computer frustrations – including this one. You can buy software that solves the problem, or you can do a little work and solve the problem for yourself using free alternatives. It’s up to you, and I want to know: which tool did you use for the job? Share in the comments below!

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