Split Your Fusion Drive Apart

How to use Terminal to split a Mac's Fusion Drive

The Fusion drive on a Mac is made up of two physical drives: an SSD and a standard platter-based drive. It combines the best of both worlds: the wonderfully fast performance of an SSD, and the large but cheap storage space of a standard hard drive.

Deleting Your Mac's Fusion Drive

man using laptop
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While the Fusion setup creates a nice performance boost for most Mac users, there may be a time when you no longer want the Fusion drive and would prefer to have two distinctly separate drives for your Mac. You may find that having separate drives is a better configuration for your data needs, or perhaps you just want to replace either the SSD or the hard drive with a larger or faster one. No matter the reason, separating the drives into their individual components is rather easy.

Disk Utility and Fusion Drives

Disk Utility does not entirely support Apple's Core Storage technology, which is the system behind the scene that allows the Fusion drive to work. Yes, you can see your Fusion drive in Disk Utility, and you can erase its data, but Disk Utility lacks a way to split the Fusion drive into its basic components. Likewise, there is no way to create a Fusion drive in Disk Utility; instead, you have to resort to Terminal to set up a Fusion drive.

Of course, if you can create a Fusion drive in Terminal, you can split one up, too. That's the method we will use in this guide to delete a Fusion drive.

Using Terminal to Delete a Fusion Drive

Deleting a Fusion drive requires three Terminal commands. As the Fusion drive is split into its individual drives, it will be reformatted and ready to use.

Deleting a Fusion drive destroys all data contained on the drives. This includes not only the normal system and user data but also any data on a hidden partition.

This is an advanced DIY process. It's a good idea to read through the entire process before starting. Take the time to back up your data, and copy your Recovery HD to a new location.

Listing Core Storage Components

How to Delete Your Mac's Fusion Drive - Logical Volume Group and Logical Volume UUID

We will use Terminal to split apart your Fusion drive. These three Core Storage commands will allow us to see the current Fusion drive's configuration. It will also help us discover the UUIDs (Universal Unique Identifiers) we need to delete the Core Storage Logical Volume and the Core Storage Logical Volume Group. Once both are deleted, your Fusion drive will be split apart.

How to Display the Fusion Drive's UUIDs

  1. Close all other apps or programs. You can leave your web browser open f you need to read these instructions.

  2. Launch Terminal, located under /Applications/Utilities/.

  3. In the Terminal prompt, enter the following command:

    diskutil cs list
  4. Press enter or return on your keyboard.

Terminal will display an overview of your Fusion drive, including all the volumes of the Core Storage system. For most people, that will just be the Fusion drive.

We're looking for two pieces of information: the Logical Volume Group UUID and the Logical Volume UUID of your Fusion drive.

The Logical Volume Group is a long sequence of numbers, letters, and dashes, and it is usually the first line that appears. Once you locate the Logical Volume Group, write down or copy/paste the UUID to a secure location; you will need it later.

The second item we need from the list is the Logical Volume. You can find it near the bottom of the display. It usually presents as a sequence of words and numbers. Once again write down or save (copy/paste) the UUID; you will need it in the next step.

Delete Core Storage Volume

Delete Core Storage Volume

Now that we have the UUIDs of the Logical Volume Group and the Logical Volume, we can delete the Fusion drive.

Deleting the Fusion drive will cause all data associated with the drive, including any Recovery HD partition that may be hidden, to be lost. Be sure to back up your data before proceeding.

The command format is:

diskutil cs delete UUID

where UUID is the Logical Volume Group you wrote down in the first set of instructions. An example would be:

diskutil cs delete E03B3F30-6A1B-4DCD-9E14-5E927BC3F5DC

  1. Launch Terminal, if it isn't already open.

  2. To delete the Logical Volume, enter the following command format into the Terminal prompt, together with the UUID you saved in the second set of instructions.

    diskutil cs deleteVolume UUID

    In this format, the UUID is from the Logical Volume, so an example might be:

    diskutil cs deleteVolume E59B5A99-F8C1-461A-AE54-6EC11B095161

    Be sure to enter the correct UUID.

  3. Once the full command is entered in the Terminal prompt, press enter or return. Once the command completes, you're ready to delete the Logical Volume Group.

  4. Be sure to enter the correct UUID from your Fusion group. Enter the above command in Terminal, then press enter or return.

  5. Terminal will provide feedback on the process of deleting the Logical Volume Group. This process can take a bit longer since it includes reformatting the individual volumes that once made up the Fusion drive.

    When the Terminal prompt reappears, the Fusion drive has been removed and you can use the individual drives as you please.

  6. If you split up your Fusion drive in order to install a different SSD or hard drive, you can go ahead and make the change. When you're ready to re-fuse the drives, follow the instructions in our article Setting Up a Fusion Drive on Your Current Mac.

Troubleshooting

  • Most problems encountered when deleting a Fusion drive come from misidentifying the Logical Volume or Logical Volume Group. Go back and take a look at the second set of instructions for details about finding the UUID for each one. The image has each item highlighted to help you.
  • Making a typo in the UUID is another common error. Make sure the UUID is correct.
  • It's common to perform the deletes in the wrong order. You must do the Logical Volume first, followed by the Logical Volume Group. Should you accidentally delete the Logical Volume Group first, you may find that Terminal never finishes reformatting one of the drives in the Fusion group. You can correct this problem by quitting Terminal and restarting your Mac. Once your Mac restarts, launch Disk Utility and reformat each drive from your old Fusion array.