Late 2015 iMac HD Split

[Skeptical.me]

Hi,

Late 2015 iMac i5 3.2Ghz 5K 32GB 1TB Fusion

I really need help with this.

I've been having issues with kernel panics on macOS Mojave. I couldn't boot into Recovery nor Internet Recovery (Both would end in Kernel Panics). Yet no issues were detected in a disgnostics test. And so I created a bootable Mojave USB Drive from my housemates Mac to do a fresh Mojave install.

However, when I was able to boot into Recovery by holding down the Option key at boot and selecting the USB Drive, then selecting Disk Utilities I saw this:

It appears as though the Fusion drive has split (Container disk0 and disk1), or am I incorrect? (edit: I was incorrect, please see further down the page, it appears the drive may have unmounted)

I ran First Aid on Container disk2:

"Running First Aid on "Container disk2"

Repairing storage system
Performing fsck_apfs - y -x /dev/disk0s2
Checking the container superblock.
Checking the EFI jumpstart record.
Warning: Could not iterate gbitmap tree to read reaper objects (old 0x18a36c) : 22
The volume /dev/disk0s2 could not be verified completely.
Storage system check exit code is 0."

I tried to reformat the drive but I couldn't:

So, I opened Terminal and ran the # diskutil list command:

Then I tried # diskutil cs to try to create a coreStorage Group, first I tried 'list', then I tried 'create'.

As you can see I am not able to create a coreStorage Group as there is nothing mounted, and of course now at boot up there's no Mac HDD displayed for selection only the USB Installer.

So, I'm not sure what to do now.

I want to:

1. Re-join the disks; and
2. Fresh Install of macOS Mojave

Any help is honestly appreciated.

Thanks.

 

[Skeptical.me]

I found the answer here:

https://support.apple.com/en-us/HT207584

However, the answer apparently is to do this in Terminal:

diskutil cs create Macintosh\ HD disk0 disk1

And as soon as I tapped the Enter key the command executed and then I had a Kernel Panic.

Everything I have tried to re-install or recover this Mac ends in a Kernel Panic, yet when I boot into Diagnotics (by pressing the key D at boot) it indicates there are no issues found.

See here: https://forums.macrumors.com/thread...constant-kernel-panics.2148452/#post-26675227

I am beyond confused ...

 

[Skeptical.me]

Should I just take it into a Apple service agent?

 

[Hater]

On the top right, on view, click "show disks" so we can see what disks it detects. One of the fusion drives might be faulty, and if it is, far better to upgrade it yourself far cheaper than what Apple will charge.

Might be a good time to upgrade anyway, 1TB NVME + 8TB WD drive would give you a 9GB Fusion drive for ~$1500, which is probably what Apple would charge for a 1TB SSD anyway

 

[Skeptical.me]

On the top right, on view, click "show disks" so we can see what disks it detects. One of the fusion drives might be faulty, and if it is, far better to upgrade it yourself far cheaper than what Apple will charge.

Might be a good time to upgrade anyway, 1TB NVME + 8TB WD drive would give you a 9GB Fusion drive for ~$1500, which is probably what Apple would charge for a 1TB SSD anyway

Ok, so maybe the drive isn't split. I lack knowledge about hardware issues like this.

I already have 22TB available to me with my NAS (internal 12TB - 10TB External).

I'm confident enough to follow the guides online to safely replace the HDD (I use to do minor repairs to PC's and Mac's in a job years ago).

Is there a cheaper option for a replacement drive that you know of? I only need a 1TB or less for the iMac. Is it possible to just put a 500GB SSD into this Model? About 500GB of that 800GB+ on the disk is just synced data with Qsync on the NAS.

Thanks a lot for the reply. Much appreciated.

 

[Hater]

Not mounted, hmm. I'm out of my depth by not being there but right click on the "Fusion Drive" header and try formatting that rather than the container below it.

You can use any normal off the shelf HDD (Or SSD) for the HDD part of the fusion drive, but i'm not sure if the NVMe part of the drive needs an Apple M2 NVME or an off the shelf one.

If it does need an Apple specific NVMe drive, and you're anywhere near Canberra, I have a 250GB one you can take to test with.

 

[nambuccaheadsau]

Your problem maybe in that 'container' listing. This is usually an additional step in formatting the drive. Being a 2015 model, the blade drive (SSD) is only 24GB which is not large enough for an operating system. My OS Mojave, no iTunes, movies and very limited photos comes in at 60GB.

Maybe remove the San Disk flash drive, and try to erase the drive, if no joy reboot from the flash drive, hold down option on restart. Hopefully you will see an install option and this will format the blade and hard drives APFS.

Formatting will erase whatever is on the drives.

 

[Skeptical.me]

Not mounted, hmm. I'm out of my depth by not being there but right click on the "Fusion Drive" header and try formatting that rather than the container below it.

You can use any normal off the shelf HDD (Or SSD) for the HDD part of the fusion drive, but i'm not sure if the NVMe part of the drive needs an Apple M2 NVME or an off the shelf one.

If it does need an Apple specific NVMe drive, and you're anywhere near Canberra, I have a 250GB one you can take to test with.

I live about 6 hours away from Canberra ... dmn it lol


As you can see I cannot install macOS Mojave as there is no disk available...

And I can't reformat the drive here as the "Erase" is greyed out (and right clicking on it did nothing) and if I try on "Container disk2" the "Erase (format) fails.

[doublepost=1540204391][/doublepost]

Your problem maybe in that 'container' listing. This is usually an additional step in formatting the drive. Being a 2015 model, the blade drive (SSD) is only 24GB which is not large enough for an operating system. My OS Mojave, no iTunes, movies and very limited photos comes in at 60GB.

Maybe remove the San Disk flash drive, and try to erase the drive, if no joy reboot from the flash drive, hold down option on restart. Hopefully you will see an install option and this will format the blade and hard drives APFS.

Formatting will erase whatever is on the drives.

Hey, thanks for the reply, much appreciated.

As I wrote above I'm unable to access Recovery or Internet Recovery. I can only access Recovery with a macOS Mojave USB Install Drive. And before whatever happened to make the Mac HD disappear (I assume its unmounted) I tried a fresh install and experienced a Kernel Panic. I was unable to erase (re-format) the drive as well.

I'm very confused.

 

[Skeptical.me]

On the top right, on view, click "show disks" so we can see what disks it detects. One of the fusion drives might be faulty, and if it is, far better to upgrade it yourself far cheaper than what Apple will charge.

Might be a good time to upgrade anyway, 1TB NVME + 8TB WD drive would give you a 9GB Fusion drive for ~$1500, which is probably what Apple would charge for a 1TB SSD anyway

I'm just going to take it to an authorized agent and get a diagnosis, if they can fix it without replacing the drive that'll be great. But if it needs a new drive I can't afford Apple pricing at the moment. I have a very sick elderly dog and vet bills without insurance is ridiculous :-(

 

[Skeptical.me]

Not mounted, hmm. I'm out of my depth by not being there but right click on the "Fusion Drive" header and try formatting that rather than the container below it.

You can use any normal off the shelf HDD (Or SSD) for the HDD part of the fusion drive, Thanks for your help, I appreciate it.but i'm not sure if the NVMe part of the drive needs an Apple M2 NVME or an off the shelf one.

If it does need an Apple specific NVMe drive, and you're anywhere near Canberra, I have a 250GB one you can take to test with.

I'm talking with Crucial for the exact SSD's they sell that are compatible with this iMac model. And they supply all the parts and tools/guides to help install

 

[Hater]

I'm talking with Crucial for the exact SSD's they sell that are compatible with this iMac model. And they supply all the parts and tools/guides to help install

I wouldn't bother, any old SSD will work. The tools and guide are nice though.

 

[Skeptical.me]

I wouldn't bother, any old SSD will work. The tools and guide are nice though.

Pretty sure now it was a surge that's screwed the iMac. I experienced the problem after a bad thunderstorm last week.