Split Your Fusion Drive Apart

1
How to Delete Your Mac's Fusion Drive

man using laptop
Ezra Bailey/Taxi/Getty Images

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

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 for doing it, separating the drives into their individual components is an easier task than Apple lets on.

Disk Utility Doesn't Come to the Rescue

Disk Utility doesn't completely 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 as well. That's the method we'll use in this guide to deleting a Fusion drive.

Using Terminal to Delete a Fusion Drive

The process of deleting a Fusion drive isn't very difficult; all it takes is three Terminal commands, and your Fusion drive will be split into its individual drives. As a bonus, they will be reformatted and ready to use.

That's an important point to remember; deleting a Fusion drive destroys all data contained on the drives. This includes not only the normal system and user data you may have stored on them but also any data on a hidden partition, such as the Recovery HD used for OS X Lion and later.

This is an advanced DIY process so take your time and read through the entire process. And before you do anything, take the time to back up your data as well as copy your Recovery HD to a new location.

When you're ready, proceed to the next page to get started.

2
How to Delete Your Mac's Fusion Drive - Listing Core Storage Components

How to Delete Your Mac's Fusion Drive - Logical Volume Group and Logical Volume UUID
The two UUID's needed are outlined in red (click to expand). Screen shot courtesy of Coyote Moon, Inc.

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 and 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 and ready for you to use as you see fit.

Display the Fusion Drive's UUIDs

  1. Close all apps, except your web browser (so you can read these instructions).
  2. Launch Terminal, located at /Applications/Utilities.
  3. At the Terminal prompt (usually your account name followed by a $) enter the following command:
  4. diskutil cs list
  5. Press enter or return.

Terminal will display an overview of your Fusion drive. Actually, it will display all volumes that are included in the Core Storage system, but for most of us, that will be just 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 usually the first line that appears; it will have the following format:

Logical Volume Group UUID

=======================

An example would be:

Logical Volume Group E03B3F30-6A1B-4DCD-9E14-5E927BC3F5DC

=====================================================

Once you locate the Logical Volume Group, write down or save (copy/paste) the UUID; 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, in the following format:

Logical Volume UUID

----------------------------

An example would be:

Logical Volume E59B5A99-F8C1-461A-AE54-6EC11B095161

----------------------------------------------------------------------------------

Once again write down or save (copy/paste) the UUID; you will need it in the next step.

3
How to Delete Your Mac's Fusion Drive - Delete Core Storage Volume

Delete Core Storage Volume
The two Core Storage commands to delete the Logical Volume and the Logical Volume Group are highlighted (click to expand). Screen shot courtesy of Coyote Moon, Inc.

Now that we have the UUIDs of the Logical Volume Group and the Logical Volume (see the previous page), we can delete the Fusion drive.

Warning: 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 from the Logical Volume Group. An example would be:

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

  1. Launch Terminal, if it isn't already open.
  2. The first thing you need to do is delete the Logical Volume. You do this by using the following command, together with the UUID you saved in step 2 (see the previous page).

    The command format is:

    diskutil cs deleteVolume UUID

    where UUID is from the Logical Volume. An example would be:

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

  3. Be sure to enter the correct UUID. Enter the above command in Terminal, and then press enter or return.
  4. Once the command completes, you're ready to delete the Logical Volume Group.
  5. Be sure to enter the correct UUID from your Fusion group. Enter the above command in Terminal, and then press enter or return.
  6. The 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.
  7. When the Terminal prompt reappears, your Fusion drive has been removed, and you can now use the individual drives as you wish.
  8. 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-out. When you're ready to re-fuse the drives, follow the instructions in 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. Take a look at page 2 for details about finding the UUID for each one. The image on page 2 has each item highlighted to help you.
  • Making a typo in the UUID is also a very common error. Make sure the UUID is correct.
  • Last but not least, it's very 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.