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iMac 2014 (Fusion Drive) not working from SDD alone?

G

grani13

macrumors member
Original poster
Mar 31, 2012
39
6
Hello,

a few weeks back my 2014 iMac died and wasn't able to reboot. Apple had a look at it and the HDD is completely gone. They formatted the system and installed OSX on the SDD portion - everything seemed fine at the store but using it at home the computer shuts down and reboots frequently (around every 15 minutes or so....). When it is switched back on there is an error message that the attached disk cannot be read (but while that computer is running)

Shouldn't the iMac (in theory) be able to run from the SDD portion alone? Did we miss something in the installation part? Or is it more complex than that?

What are my options - the iMac is not my workhorse but it would be nice to have it for one or another task...

thanks
grani13
 
grani13 said:
a few weeks back my 2014 iMac died and wasn't able to reboot. Apple had a look at it and the HDD is completely gone. They formatted the system and installed OSX on the SDD portion - everything seemed fine at the store but using it at home the computer shuts down and reboots frequently (around every 15 minutes or so....). When it is switched back on there is an error message that the attached disk cannot be read (but while that computer is running)

Shouldn't the iMac (in theory) be able to run from the SDD portion alone? Did we miss something in the installation part? Or is it more complex than that?

What are my options - the iMac is not my workhorse but it would be nice to have it for one or another task...
Click to expand...
Unless Apple opened the iMac and removed the failed HDD, it's still installed. The system will still attempt to access it. The ideal "fix" here is to replace the failed HDD with a SSD. You will then have two internal SSD. Many retailers sell DIY SSD upgrade kits w/ everything you need. Recommend you do not make Fusion Drive from two SSD. Just use them as separate drives. Reinstall macOS and boot from the larger SSD which has replaced the HDD.

Example kit:
eshop.macsales.com

DIY Bundle - 500GB OWC 6G SSD and HDD Kit for iMac

Add an SSD to your hard drive equipped iMac to experience faster booting, near instant application launches and data transfer speeds up over 500 MB/s.
eshop.macsales.com eshop.macsales.com
 
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grani13 said:
Hello,

a few weeks back my 2014 iMac died and wasn't able to reboot. Apple had a look at it and the HDD is completely gone. They formatted the system and installed OSX on the SDD portion - everything seemed fine at the store but using it at home the computer shuts down and reboots frequently (around every 15 minutes or so....). When it is switched back on there is an error message that the attached disk cannot be read (but while that computer is running)

Shouldn't the iMac (in theory) be able to run from the SDD portion alone? Did we miss something in the installation part? Or is it more complex than that?

What are my options - the iMac is not my workhorse but it would be nice to have it for one or another task...

thanks
grani13
Click to expand...

You can run your iMac entirely from external SSD via USB port.
Delete the internal drive completely, unmount both of them from the system....

Unmount a disk set or disk member using Disk Utility on Mac

In Disk Utility on your Mac, unmount a RAID set to repair it or perform other maintenance.
support.apple.com

Mac Diskutil Commands (diskutil list/erase/apfs/repair)

Learn how to use the diskutil command on Mac with verbs including diskutil list, diskutil eraseDisk, diskutil apfs, diskutil mount/unmount, diskutil repair, and diskutil eject.
iboysoft.com iboysoft.com
 
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I seen multiple different issues related to failed HDDs and failed fusion drives on my many Macs, and once on a Late 2013 iMac I seen a very similar issue, but I was trying to run on an external drive. After about 10 or 15 minutes, the Mac would Kernel panic then restart by itself.

It was weird, I didn’t have any issues with it until I upgraded the OS to Catalina from Mojave. When I boot from Catalina, it would restart about 15 minutes, if I would boot back into Mojave, no problems at all it ran great.

Another symptom I was having regardless of what OS I tried to boot from was the boot times were abnormally long for running a solid-state drive, but once the computer booted, everything seemed fine.

I open the iMac and pulled the failed HDD out, the Kernel panic went away and a boot times improved a lot.
 
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grani13 said:
They formatted the system and installed OSX on the SDD portion - everything seemed fine at the store but using it at home the computer shuts down and reboots frequently (around every 15 minutes or so....).
Click to expand...
The SSD volume on those Fusion Drives is very small -- 100 Gb if you're lucky; 20 Gb otherwise!
 
OP:

Since the iMac won't be your "main computer", if you'd like to keep it going a while longer, I'd suggest an EXTERNAL USB3 boot SSD.

You can put one together quite cheaply yourself, or buy one "ready to use".

For an old iMac, you might consider a 2.5" SATA SSD, 512gb in size. Something like:
(many others available)

Then, get an external enclosure like this:
(again, many choices available)

Put the drive into the enclosure.
Use disk utility to format it to APFS, GUID partition format.

Then, download SuperDuper from here:
(above link initiates download).

Use SuperDuper to "clone" the contents of the internal SSD to the external SSD.
It's VERY easy to understand and use. One-minute learning process.

When the clone is done, go to the startup disk preference pane and set the external drive to be the new boot drive.

Then, reboot.

That should do it.
Good luck.
 
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Thanks to all the feedback. I think I will tempt an "internal" repair so that the Mac remains more or less as is...

I think this is the right kit to repair my Mac:

www.galaxus.ch

OWC Complete HDD Upgrade Kit

Required for any drive installed in the main drive bay. Eliminates fan noise and ensures proper control of the system fan when upgrading your iMac from 2012 or newer. The only iMac hard drive upgrade option on the market that has passed the Apple Hardware Test. Resolves firmware compatibility...
www.galaxus.ch www.galaxus.ch

What I am less certain, is what kind of SDD I would need to complete this? What is the form factor and interface that I need? Something like this?

www.galaxus.ch

WD Green (2000 GB, 2.5")

In 3D V-NAND (also known as V-NAND or 3D NAND), the transistors are oriented vertically to the chip surface, and the flash memory cells are arranged in layers stacked on top of each other. This results in a higher storage density while simultaneously reducing the risk of interference between the...
www.galaxus.ch www.galaxus.ch


thanks in advance.
grani13
 
grani13 said:
Thanks to all the feedback. I think I will tempt an "internal" repair so that the Mac remains more or less as is...


What I am less certain, is what kind of SDD I would need to complete this? What is the form factor and interface that I need? Something like this?


thanks in advance.
grani13
Click to expand...

2.5" SATA is the most compatible and popular SSD to work in iMac 2014.
 
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