How to fix my split Fusion Drive (iMac) using Mojave

[Weaselboy]

What drive or drives did the technician install? I ask because I think there is only one physical drive shown there.

Look at the screenshot up in post #19 and see where it shows two "physical" drives there? I'm not seeing that with yours.

 

[casperes1996]

What drive or drives did the technician install? I ask because I think there is only one physical drive shown there.

Look at the screenshot up in post #19 and see where it shows two "physical" drives there? I'm not seeing that with yours.

Good point; That is rather curious. Hadn't even spotted that.
I've PM'ed Ellie some instructions but that is an interesting curiosity; But then in Ellie's case, what is /dev/disk1? Cause aside from it not being listed as "Physical" it otherwise looks like an independant hardware drive.

 

[Weaselboy]

But then in Ellie's case, what is /dev/disk1?

Not sure and that is why I asked the follow up. I am also suspicious the reset Fusion command seems to only see one physical drive.

 

[casperes1996]

Not sure and that is why I asked the follow up. I am also suspicious the reset Fusion command seems to only see one physical drive.

Right but resetFusion is known to not always work with disks that didn't come as a Fusion to begin with. If the IDs of the drives just don't clearly identify them as a pair of Solid State and rotational.

Told Ellie to use the diskutil ap createContainer -main <disk> -secondary <disk>

to manually specify SSD and HDD, but yeah it's a little weird that it's not labelled as physical. But it also is clearly not a synthesised container or anything, it's a disk that holds a container of its own and its internal. Bit odd, but I guess we'll find out

 

[Diegosan12346]

Not sure and that is why I asked the follow up. I am also suspicious the reset Fusion command seems to only see one physical drive.

Can you help with a problem im having with my 2017 mac i used bootcamp and idk what happened but now i think the drives are messed up i dont know what to do since im not good with this type of stuff this is how my disk utility looks if that gives you an ideo of whats wrong

 

[Weaselboy]

Can you help with a problem im having with my 2017 mac i used bootcamp and idk what happened but now i think the drives are messed up i dont know what to do since im not good with this type of stuff this is how my disk utility looks if that gives you an ideo of whats wrong.

Open Terminal and run each of the commands below, then tell me the output of both.

diskutil cs list

diskutil list

Also, what version of macOS are you on?

 

[Diegosan12346]

Open Terminal and run each of the commands below, then tell me the output of both.

diskutil cs list

diskutil list

Also, what version of macOS are you on?

Thats what i got and idk what macos im on i tried to download the macos in the recovery and it didnt work so idk before it got messed up i was on catalina

 

[EllieH]

After casperes1996 helped me repair my iMac with the Macworld article #2014011 (How to make your own fusion drive), Disk Utility and Terminal both have very short responses. The iMac is very fast again while running Mojave.

 

[Weaselboy]

Thats what i got and idk what macos im on i tried to download the macos in the recovery and it didnt work so idk before it got messed up i was on catalina

How to fix a split Fusion Drive - Apple Support

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

support.apple.com

Try this... reboot then hold command-option-r to get to Internet recovery. You should see a spinning grey globe while it downloads. Once in recovery, run the command below in Terminal. That should rebuild the Fusion drive. Once that is done, close Terminal and reinstall the OS.

diskutil resetFusion

Obviously, this will wipe any data that was there, so make sure you have a backup.

 

[Diegosan12346]

How to fix a split Fusion Drive - Apple Support

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

support.apple.com

Try this... reboot then hold command-option-r to get to Internet recovery. You should see a spinning grey globe while it downloads. Once in recovery, run the command below in Terminal. That should rebuild the Fusion drive. Once that is done, close Terminal and reinstall the OS.

diskutil resetFusion

Obviously, this will wipe any data that was there, so make sure you have a backup.

It worked, thank you for the help I guess all i had to do was do command option r and that made it so resetfusion works

 

[Diegosan12346]

How to fix a split Fusion Drive - Apple Support

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

support.apple.com

Try this... reboot then hold command-option-r to get to Internet recovery. You should see a spinning grey globe while it downloads. Once in recovery, run the command below in Terminal. That should rebuild the Fusion drive. Once that is done, close Terminal and reinstall the OS.

diskutil resetFusion

Obviously, this will wipe any data that was there, so make sure you have a backup.

I am having a problem with my windows partition again yesterday i was using windows it was working fine i turn off my computer to go to bed today i try to turn it on hold alt to open the windows drive but it doesnt work do you know whats happening or if i can fix it

 

[casperes1996]

I am having a problem with my windows partition again yesterday i was using windows it was working fine i turn off my computer to go to bed today i try to turn it on hold alt to open the windows drive but it doesnt work do you know whats happening or if i can fix it

Can be many explanations. What exactly do you mean with "it doesn't work"? Do you not see the boot-picker at all, or do you get to it, but Windows is not on the list anymore?

If it is the latter, I would assume it is a partition table issue - Bootcamp creates a hybrid MBR table inside the GPT to which Windows is installed - however, MBR is limited to 3 volumes, so if Windows update or something attempts to add an extra volume it can go wrong, since Apple already maps its Macintosh HD volume into the hybrid MBR (at least they used to when it was HFS+ - haven't checked if they still do now that there's no reading it from within Windws) and something else I've forgotten as well. - Last time I dealt with this I had to use GDisk to rewrite the partition tables, recreating the MBR pointers to only point to the Windows and Macintosh HD volumes

If the former, try with a wired keyboard

 

[fhopper]

I left mine separated and loved the speed of the internal SSD.

 

[lazlo409]

Hi there!

I know this is an old thread but I have a similar issue. Made a new account cause I'm stumped. "diskutil resetFusion" didn't work and tried doing other fixes I found on google. I've backed everything up already so I'm ok with wiping the entire drive.

I'm on the latest version of Big Sur.

 

[Weaselboy]

Unless I am missing something, all I see there is a 500GB hard drive and I don't think you ever had a Fusion drive.

Can you explain what happened to cause you to do this and what you have done so far. Also the model and tear Mac you have.

 

[lazlo409]

Unless I am missing something, all I see there is a 500GB hard drive and I don't think you ever had a Fusion drive.

Can you explain what happened to cause you to do this and what you have done so far. Also the model and tear Mac you have.

I have a 2014 MacBook Pro. I upgraded to Catalina but my main program that I use for video editing wouldn't launch (I know, stupid of me). So I downgraded to High Sierra, at this point is when my fusion drive was split. I used it for months like this just cause I needed to do some video editing and had no time to troubleshoot this. I ended up forgetting about the split completely but now I'm running out of space so here we are. I ended up getting a new version of my editing software so I decided to upgrade to Big Sur.

 

[Weaselboy]

Like I mentioned, it looks like you just have one internal drive there, so there is no way you had a Fusion drive. What makes you think you did?

So is Big Sur working now?

 

[casperes1996]

I have a 2014 MacBook Pro. I upgraded to Catalina but my main program that I use for video editing wouldn't launch (I know, stupid of me). So I downgraded to High Sierra, at this point is when my fusion drive was split. I used it for months like this just cause I needed to do some video editing and had no time to troubleshoot this. I ended up forgetting about the split completely but now I'm running out of space so here we are. I ended up getting a new version of my editing software so I decided to upgrade to Big Sur.

No laptop Apple has made has ever come with a fusion drive and unless you frankensteined an external+internal setup you cannot even make a fusion drive setup happen on the 2014 MBP.

 

[lazlo409]

I am mistaken, wow. My apologies, you are right. I know for a fact I had 1TB of flash storage on it but it failed and had to get it replaced. I never really bothered checking to see if it was in fact a 1TB storage that was replaced. But now I'm starting to think they replaced it with a 512GB drive and I just assumed something happened during the OS upgrade. So now I got a completely separate problem. Thanks for clearing that up!

 

[casperes1996]

I am mistaken, wow. My apologies, you are right. I know for a fact I had 1TB of flash storage on it but it failed and had to get it replaced. I never really bothered checking to see if it was in fact a 1TB storage that was replaced. But now I'm starting to think they replaced it with a 512GB drive and I just assumed something happened during the OS upgrade. So now I got a completely separate problem. Thanks for clearing that up!

Sorry for your issue but yeah that's a 512GB drive

 

[Michał]

Hi. I know it's an old post, but only you can help me. Tried following the previous tips but nothing helps. I have a problem with my Fusion Drive, how can I merge the drives? I am sending a picture from diskutil list, please help. Mac mini Mojave.

 

[Weaselboy]

How to fix a split Fusion Drive - Apple Support

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

support.apple.com

Follow the steps in this page under the Mojave section.

 

[Bauk18]

Thats what i got and idk what macos im on i tried to download the macos in the recovery and it didnt work so idk before it got messed up i was on catalina View attachment 948048

Hi All,

I'm having a similar problem to Jafrican in Post #15 and Diegosan123456 above with my wife 2017 27" iMac. I erased the Fusion drive and tried to reinstall Mojave, but the Fusion disk isn't found.

Found this thread and tried diskutil resetFusion but it doesn't work as there are 27 disks! I then tried diskutil ap deleteContainer disk18 (for example) and there error message states, "you must specify either an AFPS Container Reference or Physical Store. Any help will be much appreciated.

 

[Bauk18]

Hi All,

I'm having a similar problem to Jafrican in Post #15 and Diegosan123456 above with my wife 2017 27" iMac. I erased the Fusion drive and tried to reinstall Mojave, but the Fusion disk isn't found.

Found this thread and tried diskutil resetFusion but it doesn't work as there are 27 disks! I then tried diskutil ap deleteContainer disk18 (for example) and there error message states, "you must specify either an AFPS Container Reference or Physical Store. Any help will be much appreciated.

I think it's sorted. I had Mojave on the computer but the Apple instructions for "How to fix a split Fusion Drive" for High Sierra seemed to work. I'm reinstalling the OS and will see. One issue I see is I had to format it as jhfs+ but think I need APFS? I want to upgrade to Catalina.

 

[casperes1996]

I think it's sorted. I had Mojave on the computer but the Apple instructions for "How to fix a split Fusion Drive" for High Sierra seemed to work. I'm reinstalling the OS and will see. One issue I see is I had to format it as jhfs+ but think I need APFS? I want to upgrade to Catalina.

macOS will be able to automatically convert jHFS+ to APFS when necessary