Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

ZacC2024

macrumors newbie
Original poster
May 26, 2024
4
0
I upgraded to latest OS (Big Sur 11.7.10) back in April, then after multiple kernel panics I went to YouTube, tried all the tips and ultimately I ended up reinstalling clean OS, then installed OS on external SSD to boot off of in case that didn't work. For a month or so I could boot up from either the internal Fusion Drive or the external SSD with intermittent kernel panic restarts. Now I can only boot from the external SSD. On startup, when I go into recovery mode and look at the internal drives in disk utility, they show twice the capacity (4GB instead of 2GB ??), and the drive names become generic (SSD = diskOs2, HDD = ST3000DM001 Media), not the MacHD named drives I had when the trouble started. For a few weeks I was able to boot from the external disk and see the contents of the internal disk, now I get an error message on restart that says "the disk you attached was not readable by this computer, and gives me the option to eject, ignore or initialize. I have clicked ignore. I don't see these drives in finder anymore. I have noticed that when running off the SSD the runtime until next kernel panic forced restart is getting pretty short.

Questions
1. Is this solvable with fusion drive swap?
2. if not what else could be going on? I want to try to keep this machine alive until M4 refresh.
 

Nguyen Duc Hieu

macrumors 68030
Jul 5, 2020
2,913
959
Ho Chi Minh City, Vietnam
Try ejecting, unmounting, deleting all internal disks from Disk Utility to see whether it improves your situation.
They are both dead and need to be removed from your system, if not physically, then logically at least, so the OS won't have to bother about them any more.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
28,618
12,744
First:
Is all "the stuff" on the internal fusion drive backed up?

In other words, can you afford to lose it if you "wipe" the fusion drive?

WHY I'm asking:
I would suggest you make the external SSD your main boot drive, and then "erase and split" the internal fusion drive (which is actually a small SSD and a larger HDD).

It's possible that one portion of the fusion drive is failing -- this is most commonly the HDD portion, but sometimes it can be the SSD, as well.

IF you can just "erase" both of them and leave them "in place" as "standalone, but unused" drives for now, you should be able to go on using the external SSD as your main drive.

It may even be possible to "revive" the SSD portion or HDD portion, and use as a "data drive", or perhaps as a backup.

Final thoughts:
You have a Mac that is now 10 years old.
It's time to start thinking "replacement".

I'd suggest that you NOT buy another iMac.
This time, get a Mini.
Perhaps an m2pro Mini (and the display of your choice).
BE AWARE that Apple may be releasing the m4 and m4pro Minis later this year (if you can hold out).
There won't be any m3 Minis.
 

ZacC2024

macrumors newbie
Original poster
May 26, 2024
4
0
Data is backed up fortunately. I have uncounted the internal drives. both are greyed out in disk utility. The computer ran off the external SSD for about 5 minutes then does a restart. Do you think the SDD replacement for the HDD will make sense? I see a couple kits online that look sort of involved but it's only a $200 investment. I can live with my M1 MacBook Pro but I would love a new 27" M4....hoping to drag this old iMac across the finish line as a family web browser until then.
 

Nguyen Duc Hieu

macrumors 68030
Jul 5, 2020
2,913
959
Ho Chi Minh City, Vietnam
Data is backed up fortunately. I have uncounted the internal drives. both are greyed out in disk utility. The computer ran off the external SSD for about 5 minutes then does a restart. Do you think the SDD replacement for the HDD will make sense? I see a couple kits online that look sort of involved but it's only a $200 investment. I can live with my M1 MacBook Pro but I would love a new 27" M4....hoping to drag this old iMac across the finish line as a family web browser until then.

If you want a 2TB SATA SSD, then 200$ price tag is a little pricey but not very irrational.
A SATA SSD will replace the internal HDD with a 3,5" to 2.5" mounting kit (cheap one cost only 5$ or less) or just tape it to the aluminum case.
5" restart when using external SSD may be caused by defective external enclosure or bad SSD, or for worse, by internal defectives.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
28,618
12,744
OP wrote:
"The computer ran off the external SSD for about 5 minutes then does a restart."

This suggests that something else might be wrong inside, beyond "just the drives".

My advice is:
Boot and run from an external SSD.
If necessary, erase both components of the fusion drive (SSD and HDD).
If you're still having problems, don't spend any more money on this. It may not help. The iMac is now 10 years old.
It's time to look for a replacement.

Next time, I recommend going with a Mini.
 
Last edited:

ZacC2024

macrumors newbie
Original poster
May 26, 2024
4
0
rolling the dice on the ifixit hdd to ssd replacement will report back. worst case scenario I get a decent priced ssd and waste a couple hours trying to resurrect a nearly dead 10 yo Mac. my 2008 iMac I never use is still humming along lol.

mini seems like a good option thx
 

shorty135

macrumors newbie
May 17, 2024
4
0
rolling the dice on the ifixit hdd to ssd replacement will report back. worst case scenario I get a decent priced ssd and waste a couple hours trying to resurrect a nearly dead 10 yo Mac. my 2008 iMac I never use is still humming along lol.

mini seems like a good option thx
I am really interested in seeing what you ended up doing and how it is working out for you. I have the same late 2014 imac configuration and it was crashing with an error log pointing to a problem with my internal drive. I am trying to run the iMac with a $80 external SSD from Costco (takes a couple of minutes to get to the log in screen after power up). Can I ask what was the cost for getting ifixit to replace the fusion drive with an internal SSD? What O/S are you running?
 

ZacC2024

macrumors newbie
Original poster
May 26, 2024
4
0
I am about to embark on the journey - I will let you know how it goes soon. Got the kit from ifixit 2gb ssd. mainly because the instructions seem pretty bullet proof and I haven't done this before. you can just get the tools from them without the drive. close to $200 for everything which is more than the crucial SDD by itself on Newegg for some reason.
 

shorty135

macrumors newbie
May 17, 2024
4
0
I am about to embark on the journey - I will let you know how it goes soon. Got the kit from ifixit 2gb ssd. mainly because the instructions seem pretty bullet proof and I haven't done this before. you can just get the tools from them without the drive. close to $200 for everything which is more than the crucial SDD by itself on Newegg for some reason.
When I booted the iMac from an external SSD running Big Sur, it was still crashing during sleep mode. When the iMac was on Mojave, it did not crash. Since it was crashing when it was running Big Sur, I tried to install Big Sur onto an external SSD to see if it would perform better. If the iMac was not not in sleep mode, browsing the internet was a lot quicker when I booted the iMac from the SSD. Since the iMac is still crashing when it is in sleep mode, I am attempting to install a newer operating system onto the external SSD (with OCLP) and hoping that there is a newer O/S version that would not cause the iMac to crash when it goes into sleep mode.
 

pshufd

macrumors G3
Oct 24, 2013
9,988
14,462
New Hampshire
I bought a 2015 iMac 27 about 8 months ago and it had the standard 1 TB HDD and it's perfectly healthy. The machine apparently wasn't used very much. I hooked up an old EVO 860 SATA3 SSD to it with Monterey and have been running it off the external SSD as that was my overall plan. The machine runs fine. It's often up for 2 months at a time getting rebooted only for updates.

I've read reports about using NVMe external SSDs on Macs where they can cause crashes or hangs. I've never tried to run off of those as the performance wouldn't make a difference because of the limitations of the interface but it's possible that this is a problem if you're using an NVMe drive. I do have an NVMe drive on my Mac Studio and it's had a few disconnects.

I've run Macs off of USB3 external SSDs - MacBook Pros, Mac minis, etc. with no problems.
 
  • Like
Reactions: shorty135

shorty135

macrumors newbie
May 17, 2024
4
0
I bought a 2015 iMac 27 about 8 months ago and it had the standard 1 TB HDD and it's perfectly healthy. The machine apparently wasn't used very much. I hooked up an old EVO 860 SATA3 SSD to it with Monterey and have been running it off the external SSD as that was my overall plan. The machine runs fine. It's often up for 2 months at a time getting rebooted only for updates.

I've read reports about using NVMe external SSDs on Macs where they can cause crashes or hangs. I've never tried to run off of those as the performance wouldn't make a difference because of the limitations of the interface but it's possible that this is a problem if you're using an NVMe drive. I do have an NVMe drive on my Mac Studio and it's had a few disconnects.

I've run Macs off of USB3 external SSDs - MacBook Pros, Mac minis, etc. with no problems.
Thanks for that information. I just read that Sandisk SSDs have slow loading time for Ventura and Monterey (when they are used as external boot disks).
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.