2014 Mac Mini: fusion drive question

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icwvx Author

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109 points

2014 Mac Mini: fusion drive question

Normally I clone a Mac OS & programs from a good working machine to an external drive.

Then I boot a 'new [to me] machine' from the external and reformat it's internal then clone the external to it.

I thought to first run this Terminal command while the a 2014 Mini w/ FUSION drive is running from an external drive:

diskutil cs delete "Macintosh HD" [or whatever the name is of the Fusion drive in the Mini]

Now being de-fused, then w/ the Disk Utility app, reformat the TWO internal Mini drives that show in place of the Fusion drive, and clone to them.

Comments appreciated.

Posted on Jan 12, 2025 03:57 PM

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Answer 1

Jan 15, 2025 10:42 AM in response to icwvx

Why do you want to split the Fusion Drive?

icwvx wrote:

...So my question regarding this is can an external drive containing an Mac OS installer be chosen INSTEAD of the Internet?

Yes. An external drive can be chosen if it's a proper bootable device.

❝Change your startup disk once

- Shut down your Mac.
- Press and hold the Option key as you press the power button to start up your Mac.
- When you see the available startup disks, select one, then click the .❞

If your external drive is bootable it will be displayed as an available startup disk. A cloned copy of an internal boot drive should be selectable.

A flash drive that simply has an OS installer copied onto it is not bootable. That flash drive has to be processed into a bootable USB installer before it can be used to boot the Mac.

To create a bootable USB installer on a flash drive, then this is the guidance you should be following: Create a bootable installer for macOS - Apple Support

Your 2014 Mac mini can run any macOS version from OS X 10.10 Yosemite thru macOS 12 Monterey.

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Answer 2

Jan 12, 2025 04:51 PM in response to icwvx

Reinstalling macOS from an Apple source download is not risky. In fact, it's the method drawn on by the recovery process for a Mac that cannot boot from its own recovery partition for some reason. As long as you have a solid internet connection the process is stable and relatively straightforward.

How to reinstall macOS - Apple Support

Splitting a fusion drive can only be done when booted in recovery mode or from an external drive.

Likewise, fixing a split drive can only be done when booted in recovery, when booted from an external drive or when the computer is in target disk mode being accessed by another Mac.

Here is some of Apple's guidance for fixing a split fusion drive:

How to fix a split Fusion Drive - Apple Support

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Answer 3

icwvx Author

Level 1

109 points

Jan 12, 2025 04:30 PM in response to icwvx

By default the Fusion drive is called Macintosh HD and this will kill it without having to fuss with UUIDs.

[CODE]diskutil cs delete "Macintosh HD"[/CODE]

Then use Disk Util to format both drives and install the OS in the flash drive and you are done.

I do necessarily want to install an OS from the internet.

Can one de-fuse a fusion drive in a Mac that is running from an external?

If so, what would the Terminal command syntax be, since Terminal needs to know the fusion drive location.

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Answer 4

icwvx Author

Level 1

109 points

Jan 12, 2025 06:06 PM in response to D.I. Johnson

"Reinstalling macOS from an Apple source download is not risky"

Yes I know however my internet connection generally has so much traffic that such can take hours.

Thanks DIJohnson for the Apple link however I want to split not fix. Can you advise of the syntax for the command when using Terminal when booted from an external drive

Example: diskutil cs delete Macintosh HD (assuming the fusion is thus named)

However one would need an identifier I would think - i.e. disk0s1 OR s2 OR s3 etc.

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Answer 5

Jan 12, 2025 07:07 PM in response to icwvx

You're welcome.

I can't advise you with this, but I have a link to an old Macworld article dated 2012 that is right up the alley.

Please see: How to split up a Fusion Drive | Macworld - macworld.com

I hope you find it useful. 🤞🏽

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Answer 6

icwvx Author

Level 1

109 points

Jan 15, 2025 08:31 AM in response to D.I. Johnson

"link to an old Macworld article"

Thank you. Such states:

If you split up a Fusion Drive you got from Apple, you won’t be able to use Disk Utility to format the drives.

Exit Terminal after you delete the CoreStorage setup, and choose to reinstall your OS from the list of choices in Recovery Mode. You can select which drive to install the OS on, and upon booting you’ll have access to both your drives.

----

So my question regarding this is can an external drive containing an Mac OS installer be chosen INSTEAD of the Internet?

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Answer 7

icwvx Author

Level 1

109 points

Jan 15, 2025 11:29 AM in response to D.I. Johnson

"Why do you want to split the Fusion Drive?"

To replace the PCIe card w/ a larger one. This seems much easier than removing the 'fused' HDD/PCIe and putting in an SSD, plus a PCIe wold be faster.

"Yes. An external drive can be chosen if it's a proper bootable device."

If one is to de-fuse the process requires installing an OS while still in Recovery mode.

Normally the original OS is downloaded from the Internet (OSX10.10 for this 2014 Mini).

So I wanted to know if the Internet installation is the ONLY option.

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Answer 8

icwvx Author

Level 1

109 points

Jan 12, 2025 04:32 PM in response to icwvx

Readers should ignore the first post.

Such has been simplified and re-posted.

Thanks for your comments!

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2014 Mac Mini: fusion drive question

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