Mac Instructions: Disconnect or undo Fusion Drive

Mac computer HDD and SSD separate, disconnect, disconnect

Some time ago I showed you how to make a Create Fusion Drive can, and now I thought that some users of the Apple Mac, iMac or MacBook want to disconnect or undo the Fusion Drive. The following instructions are intended for this purpose. If you want to dissolve the Fusion Drive, i.e. use the HDD hard drive and SSD hard drive separately again, then I hope that the steps outlined below will help you.

Apple Fusion Drive but that you make a backup.” width=”620″ height=”290″ /> Disconnecting or undoing the Fusion Drive is not that difficult. It is important before dissolving the Apple Fusion Drive but that you make a backup.

Preview: Disconnect or undo Fusion Drive

Before you carry out the steps described below on your Apple Mac, you should definitely make a backup, i.e. move all your data from the SSD and HHD hard drive to an external hard drive, to the cloud and / or to other storage media! Because dissolving the Fusion Drive on the Apple Mac ensures that all data and files are deleted from the SSD and HDD. Without the backup, they are then irretrievably lost. Also keep in mind that after disconnecting the Fusion Drive, you will have to reinstall the system and programs and make new settings.

Internal or external plate composite?

As is always the case with such system matters, everything is not straightforward and is seldom easy to understand. However, I will try to explain the individual steps to you Undo Fusion Drive as clearly as possible.

First, we check whether your Fusion Drive is external and the operating system itself is stored on an internal disk - or whether the two internal hard disks have been connected to form a Fusion Drive. If the disk network is external and the OS is on a separate disk, the Mac will start normally. If the internal plates are connected to a unit, then press the CMD key and R at the same time when the Apple Mac starts up. cmd + r puts the computer in the so-called Recovery mode.

Dissolve Fusion Drive: this is how it works!

The first step is to start it Port, in order to track down the two individual components of the storage group there. Once you have the terminal open, give the command discuss the coreStorage list a. After confirming the individual hard drives (Physical volume) in the corresponding group (Logical Volume Group) is displayed. The first entry is “+ - - Logical Volume Group long number“Mark the long identification number and copy it (CMD + C).

In step two you give the command in the terminal discussil coreStorage delete UUID long number a. The abbreviation UUID stands for the identification number that you have copied and which you can now paste into the command instead of the “long number”. Attention: If you now confirm the command, the Fusion Drive will be dissolved and both hard drives will be formatted, i.e. deleted. If that's okay, then confirm the command. Finished.

Set up macOS again: Internet or boot stick

Great, now you have an expensive Mac standing around, but you can't do anything with it. Because after dissolving the Fusion Drive, the hard drives are empty and even the recovery partition for the new installation of the Apple operating system macOS is gone. Now, if you want to use the Mac or iMac again, you have to feed the OS from an external source. On the one hand, this works via an internet connection; even easier but with a macOS boot stick. You will learn how to create such a bootable USB stick in this manual. Too heavy Then use the app Boot buddy.

Instructions as video

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29 Responses to “Mac Guide: Disconnect or Undo Fusion Drive”

    1. I'm not 100% sure since I didn't have the case, but I think you can only format these one at a time and use them as new hard drives. The Fusiondrive is probably dependent on the Mac it belonged to ... I think. If this is not the case, the Mac should recognize the drives as a drive again if they were connected at the same time as the system was booting. But I'm afraid that is not intended.

  1. Hello, I successfully disconnected my 128GB / 2TB Fusion Drive and restored or installed Mojave. Unfortunately, the setup of Bootcamp with Windows 10 no longer works. The iso image is no longer recognized and you cannot create a partition for Windows. After I set up the Fusiondrive again, Bootcamp ran again immediately.

    1. Hello Sven! So I don't know about Bootcamp. I installed that once and then switched to Parallels Desktop after the battle with the appropriate drivers. That makes everything I want very comfortable for years ...
      But maybe another reader has a tip about your problem ?!
      VG! Jens

  2. Thanks for the link, you could have found it yourself.

    Now I have a question, in the terminal I'm at "[-bash-3..2#" and the command doesn't give me a list.

    Am I in the wrong area or do you have an idea? :)

    1. Hello Jan! You typed “diskutil coreStorage list” and got no output? If necessary, we can also easily disconnect the Fusion Drive, since you will completely flatten the Mac anyway: You start it with the CMD + R key pressed so that it boots in recovery mode. Then you choose Disk Utility and erase the internal disk. Then you can install the system freshly on the internal disk.

      1. Yes, really strange, unfortunately nothing was listed for me. I've now solved it the separate way. Thank you and keep going with the great blog. :)

  3. Hello Sir Apfelot, the instructions for creating and dissolving a Fusion Drive are really good. Thanks a lot for this.
    When I converted my Mac Mini 2012 from the FD to a large SSD, the upload to iCloud Drive no longer worked. Apple support said that it might be because the Mini no longer has a Fusion Drive. I restored it with the old HD and the new SSD, but the upload still doesn't work. That brings me, Apple Support and a computer technician to the end. I'll have to live without iCloud Drive then. Or do you have any advice?

    1. Hi Michael! Unfortunately, I have no idea what it might be, but I have an idea how it might be solved. If you currently have a Fusion Drive consisting of an external HDD and an internal SSD, the speed should not be as good as with two internal drives anyway. For this reason, you may be able to connect an external SSD and copy the system to it (without Fusion Drive). Then you always start from the external SSD and benefit from its speed and you no longer need a Fusion Drive. As an external SSD, you could use a SanDisk or Samsung to take. I usually use SanDisk as they are cheaper per GB. Do you think this could help with you?

  4. Hello Sir Apfelot,
    Thanks for the tip. I only created the FD for testing, it should never be used properly. The performance of the new SSD alone is better. I just wanted to know if restoring would fix the problems with the iCloudDrive upload (Apple support assumption). But it didn't.
    I will only use the internal SSD and forego the iCloud Drive.
    Greetings from the North

  5. Good day

    First of all, thank you very much for the instructions. If you have now converted from HDD to SSD, how is the Fusiondrive with the blade (here 32GB) restored after it was separated by the terminal? Is this done automatically after you restart the OS in recovery?

  6. Hello
    I have an old iMac 27inch (late 2014) with an internal Fusion drive. One HDD and one SSD. The HDD is now broken but I was able to save the data on an external disk. Now I just want to install the OS on the still intact SSD and use the data from the external disk. But if I start with CMD R and then enter discuss coreStorage list in the terminal I get “No CoreStorage logical volume groups found”. What am I doing wrong?

    1. Hello Sellini! I assume that's because the drive is software 'defective' for him. Try using Disk Utility to find and erase the internal SSD. That should actually work, because I just had a similar case here in the family.

  7. I'll hang on here and hope that my question is placed correctly.

    I want to install an internal SSD in my wife's iMac (27 late 2014, High Sierra). The SSD has been running quite well externally via USB 3.0 for some time. But I don't like the cables and I want to install them now.

    Now I'm not sure how to deal with the Fusion Drive setup.

    Do I understand correctly that I first disconnect the FD and "flatten" everything? If I then replace the HDD with the SSD - can I be sure that the computer will always recognize the SSD as a boot device or will I get into trouble?

    I don't really care about the 128 GB SSD from the Fusion Drive at first, I want the change to run as smoothly as possible.

    Thanks for some advice

    1. Hello Hans! I'm not someone who tinkers with my Mac. For that reason I can't tell you whether he would also use the SSD to boot if it was internal. But I strongly suspect that you will have to dissolve the Fusion Drive first before installing the platter. If at all possible, I would then test the iMac setup before you put the disk back on.

  8. Hello, I just replaced my internal HDD with an SSD (on an iMac 27 late 2014 Big Sur with Fusion Drive)
    Before I had cloned the HDD to the SSD with CCC. Everything works. But now I still have the Fusion Drive. Is that stupid now? I wonder if this will make me lose speed or if it doesn't matter ...

    1. Hello Sebastian! Theoretically, you could lose a bit of speed because the Mac now has to access two SSDs instead of just one. But I think you don't notice that in practice. What is important, however, is that you always have a greater risk of data loss with a Fusion Drive, as you have two hard drives, each of which would produce a complete data loss in the event of a failure. So always diligently make backups and maybe also a service like Backblaze additionally use.

  9. Hello Jens, I would like to upgrade my 5k iMac (late 2014, 3TB Fusiondrive) with a 1TB Blade SSD and a 2TB SSD. Since it doesn't really make sense to create a Fusiondrive again later, I wonder whether the MAC can still be restored from the Time Machine backup after the OS has been reinstalled.
    What do you think about that? Thank you.

    1. Hello Stephan! Yes, in theory it should work like this. After installation, macOS will ask if you want to restore data from a Time Machine backup. But unfortunately that is always quite shaky. Sometimes Migration Assistant just pops up a message that the process cannot be completed. And then there you are... that's why I would always make an additional 1:1 backup of the system hard drive. Carbon Copy Cloner or SuperDuper! helps here.

  10. I have an iMac 18.3 here. with a 2TB Fusiondrive. This is getting slower and slower. extremely now at boot. I've already done everything you do on the software side... took all parts out of the launch demons. Removed all startup objects that are not absolutely necessary. Dropbox switched off when the computer started, PR RAM reset done, everything removed from the desk and placed in the documents folder, photo APP. Disconnected from iCloud, plugged in all external USBs, created a new admin user and tried... ––– no improvement. B What else is there? Software side? Now I'm at the end of my wits and suspect that it's something to do with the very small internal apple ssd that works together with the internal hard drive as a fusion drive. It can't be due to the disk space either, since almost half is still free.

    1. Hello Albertyy! Is the iMac a lot of airing? Sometimes the ventilation slots are dusty, the iMac warms up, cannot cool down and slows down the processor. You could check the activity monitor to see if someone is using +100% CPU. Otherwise, if you think it could be the Fusion Drive, then you can install a fresh system on an external hard drive (or preferably an SSD) and boot from that drive. If it's fast then your Fusion Drive could be defective. Then a backup would be urgently needed. Feel free to report back if you find something new.

  11. I replaced the homebuilt fusion drive (both drives) in my Mac Mini with a new SSD in late 2012. When I boot from the OCLP USB drive to install the OS, the system doesn't see the SSD at all. I cut the cable from the mechanical hard drive instead of removing it from the OWC doubler kit that the previous owner used for the Fusion drive. However, I no longer have an easy way to connect both old drives. Is there an easier way to get my Mac to "see" the SSD?

    1. Hello Len! Unfortunately, I'm not really up to date on the subject. I've never opened my Mac and accordingly I don't have the knowledge to give you tips here. Sorry.

    2. Argon analytics

      What is a homemade fusion drive? What kind of SSD is used? Has the fusion function via terminal been resolved? How was the SSD formatted? Have you also looked in the hard disk utility in recovery mode to see if the SSD appears there?

  12. Hello everyone,

    I need to recover data from a 2017 iMac HS using a Fusion Drive. I'm afraid that the drives will be merged and the information on the mechanical drive won't be as easy to read if you just put it in a 2,5 sata usb enclosure?

    Did anyone else do this before?

    Thank you

    1. Hi Krysstoff! I think if you still have both hard drives, then it should also work if you connect them via a housing or other adapter. But I haven't done it yet.

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