OS Upgrade Failed; Disk Utility Shows an SSD and won't boot

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Level 1

4 points

OS Upgrade Failed; Disk Utility Shows an SSD and won't boot

I'm updating my Mac mini (Late 2014, 1TB HDD) from OS X El Capitan to Big Sur. 60 GB of free space on the target partition, but the install failed and Disk Utility now shows I have both an HDD and an SSD drive.

My 1TB SATA HDD is partitioned in half: MacOS and MacOS-Clone (I cloned my El Capitan install and data so I can run legacy software).

The Big Sur install on the MacOS partition failed at the dreaded "one minute remaining" mark. The drive rebooted several times before I saw the prohibitory symbol (circle w/ line through it).

I rebooted in Recovery mode and ran Disk Utility; no errors. But the MacOS-Clone partition started up — not my previously designated startup disk.

Disk Utility reports that I now have two drives in the machine: Apple HDD (disk1) and Apple SSD (disk0). Apple HDD has two partitions: MacOS-Clone and Untitled (formerly my MacOS/startup disk and hopefully my Big Sur partition).

The "new" disk is named Apple SSD SM0128G Media, an Untitled 121.33 GB PCI Internal Physical Disk.

I have a Time Machine backup from the old MacOS but no drive to restore it to, unless I overwrite my MacOS-Clone.

I'm thinking I will need to erase the entire machine and start with a fresh install of El Capitan (the last OS that worked properly).

Any thoughts are welcome. If you want more tech details, some appear below.

Mac mini (Late 2014)

Hardware Overview:

Model Name: Mac mini

Model Identifier: Macmini7,1

Processor Name: Intel Core i5

Processor Speed: 2.6 GHz

Number of Processors: 1

Total Number of Cores: 2

L2 Cache (per Core): 256 KB

L3 Cache: 3 MB

Memory: 16 GB

Boot ROM Version: 431.6.0

SMC Version (system): 2.24f32

Apple SSD SM0128G Media

121.33 GB PCI Internal Physical Disk

One GUID Partition: Untitled (121GB)

S.M.A.R.T. status: Verified

Child count: 2

Type: Solid state

Device: disk0

APPLE HDD HTS541010A9E662 Media

1 TB SATA Internal Physical Disk

Two GUID Partitions: Untitled (443GB) and MacOS-Clone (556GB)

S.M.A.R.T. status: Verified

Child count: 4

Type: Disk

Device: disk1

Mac mini, OS X 10.11

Posted on May 4, 2022 12:12 PM

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Answer 1

Top-ranking reply

chuckbl

Community Specialist

May 6, 2022 6:55 AM in response to GerryC33

GerryC33,

Those entries in the Disk Utility could be due to a split Fusion Drive. This resource has more details on a possible fix: How to fix a split Fusion Drive - Apple Support

Those steps would permanently erase any data on the drive, so definitely make sure you have an updated Time Machine backup beforehand.

If you need any further assistance with that process, you'll want to reach out to Apple Support: Contact - Official Apple Support

Take care.

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Answer 2

JovonaP.

Community Specialist

May 5, 2022 10:15 AM in response to GerryC33

Hello GerryC33,

Thanks for using Apple Support Communities. You've done a great job trying to get this resolved so far! At this point we recommend that you reinstall macOS using the steps in the following resource:

How to reinstall macOS

Let us know the results. Be sure to include specific error messages and any other troubleshooting steps you may have tried.

Cheers!

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Answer 3

GerryC33 Author

Level 1

4 points

May 6, 2022 6:44 AM in response to JovonaP.

Thanks for the encouragement Jovona. I first attempted a Time Machine restore; a time-consuming mistake.

Next I restored the macOS through Disk Utility. High Sierra was the OS offered there and the installation was successful.

I still have the phantom SSD drive that appeared after the attempted upgrade to Big Sur. Will tackle that issue next.

Best practices (to save time and headache) would have been:

complete backup through Time Machine
erase drive through Disk Utility
reinstall macOS through Disk Utility
test macOS reinstallation
use Migration Assistant to restore profile(s) from Time Machine

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Answer 4

May 5, 2022 10:26 AM in response to GerryC33

> I'm thinking I will need to erase the entire machine and start with a fresh install of El Capitan (the last OS that worked properly).

That is the best solution.

I have used Mojave, Catalina, Big Sur and Monterey from the some disk and from the same APFS container with no problems. Creating, deleting and re-creating APFS volumes has been OK in the external disk. I have used the Apple installer and Carbon Copy Cloner.

But unlike those, El Capitan does not support APFS so I'd install it on an external disk. Or use Mojave which supports APFS and 32-bit apps (the oldest apps might have problems, though).

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Answer 5

GerryC33 Author

Level 1

4 points

May 6, 2022 7:03 AM in response to Matti Haveri

Thanks for your suggestions, Matti -- you clearly have a better grasp on using multiple OS. I'm going to be practical and not try to jam old software onto my updated machine; instead I'll resort to plan b, which is using my older mac mini.

I still have this phantom SSD that appeared after the Big Sur update failure. I'm wondering if you have any thoughts about that.

When I reboot using the Option key, it shows up with the title "Recovery". System Information>Storage shows it as an untitled volume, disk0s2, PCI protocol, with 120GB. System Info shows my primary drive as MacOS, disk1s2, SATA protocol, with 999GB.

This machine was purchased with a single 1TB HDD. It now lists a 1TB HDD and a 120GB SSD. Where could that have possibly come from?

Regarding the recovery of my data, please see my reply to Jovona. I spent way too much time attempting to restore from Time Machine, when I should have just reinstalled the OS. Selectively restoring from Time Machine (User accounts and Computer settings, and holding off on Apps and Documents until the installation is tested) would have saved two days of lost efforts. Hard to think clearly when in panic mode.

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Answer 6

May 6, 2022 7:16 AM in response to GerryC33

Hi GerryC33,

The 120 GB could be a recovery partition. On Macs there are a couple of options for recovery. One being internet recovery, one is erase all files and restart with a fresh macOS. This could be those files set aside for recovery locally.

Cheers!

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Answer 7

GerryC33 Author

Level 1

4 points

May 6, 2022 7:16 AM in response to chuckbl

Thanks chuckbl! That is exactly what I needed. I'll follow the steps in that link once I catch up on my lost work.

The macOS offered during reinstallation was High Sierra. After reading the split Fusion article, I believe I can upgrade the OS to Mojave before backing up my data and rebuilding the Fusion drive -- the Mojave+ method is less complicated.

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Answer 8

GerryC33 Author

Level 1

4 points

May 6, 2022 8:19 AM in response to merlinapple

Hi merlinapple -- yes, the 120 GB looks like a recovery partition, likely created during the attempted Big Sur os upgrade that started this mess. chuckbl's split Fusion drive advice is my best solution; the 120 GB recovery partition was not accessible in recovery mode, and first aid did not work on it. So I'll work on fixing the split Fusion drive as described above.

Big thanks to all who have helped me identify these issues!

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Answer 9

May 6, 2022 11:43 AM in response to GerryC33

Erasing the whole device (not just the volumes under it) should erase also the recovery partition (I have no experience from fusion drives but I presume they behave the same?). Of course you must be booted from another drive for this to work. And I'd recommend always having at least one bootable drive before nuking the other.

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OS Upgrade Failed; Disk Utility Shows an SSD and won't boot

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