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Model A1419 / Late 2013 / 3.2 & 3.4 GHz Core i5 or 3.5 GHz Core i7 Processor, ID iMac14,2

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Fusion Drive iMac won't boot, Mechanical HD failure?

My iMac is giving me the 'circle slash' on a black screen when trying to boot. I ran recovery this is what I'm seeing in Disk Utility (see attached image). Does this mean that the mechanical hard disk has failed?

And if so, the repair procedure would be: Replace mechanical HD, use fusion utility to rebuild drive, reinstall os?

Block Image

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Fusion Drives are a bit mysterious! You have two physical drives the HDD and a special cache drive which sits on the back side of the logic board. The OS deals with the caching on its own, you don’t see it within Disk Utility only the HDD.

The best way to deal with this is to reformat the HDD fully to see if that resolves the issue. But you first need to backup anything you don’t want to loose and you need a bootable external drive a 32GB USB thumb drive will do here.

Use disk Utility to wipe the thumb drive and then run the OS installer program to prep the drive. Once done you may want to copy the OS installer to the drive so you can then repeat the same process on your internal drive.

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They certainly do seem mysterious! :-)

This was either a 1TB or 2TB fusion drive. Only 121GB are showing up in disk utility and I get an error when I try to format/erase/repair.

I guess I'm trying to assess whether it's worth trying to fix. If it's just the mechanical drive, then I'd do it. If it's both, then probably not.


Forgot to mention, there's nothing on this machine that needs to be backed up.


@cg4n6 - Are you booting up from the external? If not you can’t format the drive!


I'm booting into the recovery console. Maybe fusion drive machines are different? I have formatted drives via recovery disk utility many times.

In disk utility I'm not even seeing the full 1 or 2 TB (I can't remember which this has). Only a "122GB apple ssd" is showing up

I'm wondering if anyone has seen this particular behavior before and if it indicates a mechanical hard drive failure.


@cg4n6 - What you are seeing is the firmware/recovery volume. This is not your data volume. The rub here is the recovery OS is either El Capitan or Sierra (just don’t remember which) yet the macOS you are currently is based on APFS not the older HFS+ which is why you need the external bootable drive based on what the system was running.

Basically, the older OS has no idea how to deal with drives which are running APFS. The volume you are seeing is a FAT32 volume which the older Utility can see!

Download from here the needed OS How to download macOS and follow this guide to create the bootable external thumb drive Create a bootable installer for macOS


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Chris Good zal eeuwig dankbaar zijn.

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