Can I split the fusion drive and use macOS with mechanical hard drive on Mac mini

That is an original Apple (Seagate based) hard drive, not an SSD. While the hard drive has no bad blocks listed, the Load Cycle Count is over 7 million which is extreme. Most hard drives have a maximum expected value for this attribute of between 600K - 900k.

In my personal experience when the Load Cycle Count attribute reaches its lifetime expectations, then the hard drive tends to have performance issues and may even act a bid oddly at times....yours has exceeded its lifetime expectations by at least 7 times.

You should definitely be using a different drive.

tomazo Said:

“split Mac mini hdd: Hi ! My 2014 macmini have a failed ssd(S.M.A.R.T say it will fail soon) Is´t possible to split the fusion-drive and use Mac OS on the mechanical hard drive!?: thanks in advance / Tomazo.”

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Using A Split Fusion-Dive in and SSD and an HDD:

Apple makes no mention of this being an option, nor not an option. It can be done unintentionally, as if can be performed, no matter the method (SSD and HDD in your instance). See here: About Fusion Drive, a Storage Option for Some Mac Computers - Apple Support

Back Up Fist:

1. Go Here: How to Fix a Split Fusion Drive - Apple Support
2. Scroll to: About Fusion Drive, a storage Option for Some Mac Computers - Apple Support
3. Scroll to: Use Terminal to create a Fusion Drive again
4. As it Reads: These steps permanently delete all data stored on the drives that make up your Fusion Drive. Make sure that you have a backup before continuing.

I don't know about your main question but I would suggest you buy a cheap USB 3.0 1 TB SSD and install the operating system on that.

Then boot your mini from the new SSD.

Even though the USB SSD will be slower than the mini's SSD you will find that your computer performs just as fast as using the internal SSD.

Crucial make a good quality 1 TB SSD for around £60 but any will do.

CRUCIAL 1TB SSD

tomazo wrote:

Hi ! My 2014 macmini have a failed ssd(S.M.A.R.T say it will fail soon) Is´t possible to split the fusion-drive and use Mac OS on the mechanical hard drive!?

thanks in advance / Tomazo.

Splitting the Fusion Drive will destroy the data on it. Before you split the Fusion Drive, I would recommend backing up your data to a new drive (if you can) – and having at least one working, bootable external drive to use to start up the system. (I don't know how reliable Internet Recovery is for older Macs these days.)

Just a hunch – but you may find that it is the mechanical hard drive that is failing, not the tiny SSD. In that case, you would not reinstall macOS on the failing drive and carry on. You would want to replace that drive – preferably with a SATA SSD big enough that you would not want or need to reconstitute a Fusion Drive afterwards.

Run DriveDx (free trial period) and post the complete text reports for both the internal SSD and HD. If the SSD is showing a SMART failure, it may not always be fatal. I've been running a couple of SSDs for years now which show a SMART failure. It all depends on what health attribute is causing the alert. Unfortunately the Apple SSDs don't have much health information available so it can be tricky to figure out if the SSD can be continued to be used safely.....you definitely want to have frequent & regular backups though just to be safe (you should already have them anyway).

“this explains how to fix it back to fusion drive!”

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That’s how I comprehended it.