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Identifying Disk Failure on iMac 27" 2019 Fusion

I have a fusion drive on my 2019 27" iMac and have suffered a disk failure. How do I identify whether it is the blade SSD or the HDD? If it is the HDD, can I simply replace just that with a suitable SSD? Do I have to 'break' the link or remove the blade SSD?

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Sadly, you really need to replace both as you can’t really reuse the blade SSD and the HDD is likely shot.

Now as you need to dig to the blade SSD why don’t you replace it with a much larger blade SSD, let’s say 500GB as a baseline and if your workflow is heavy boost it to a 1 or 2TB drive. Even still I would throw in a new SATA HDD or SSD for my deeper storage. Basically, creating two independent drives one for the OS and Apps with enough free space for both to have enough elbow room to balloon out as needed. The SATA drive will hold your more static media and your finished work. The Blade drive should have enough space to have your current project/s and to be safe, copy them to the SATA drive every so often in case you fumble up you can easily recover. Don’t forget to have a good off system backup solution.

And lastly don’t forget your RAM ideally you want at least 16GB, but again if your workflow is heavy going to 32GB may make sense.

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Thanks, this is helpful. I am unfamiliar with the concept of the fusion drive(s) having before only encountered single internal hard disks, so two questions: (1) will I have a heat issue with a larger blade SSD (I expect 500GB will be fine for my needs bit may go to 1TB) and (2) your answer suggests I will need to manage the allocation of data between the blade and the deeper storage SSD (I would avoid another SATA). Surely the iMac will manage this?

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@philip34921 - The heat is really not an issue, there’s enough air flow within the system, for piece of mind I would install this great App TG Pro it will allow you to monitor the heat and if needed ramp up the fan to cool things back down.


Flat multi-drive spaces aren’t without risks, read up on RAID to see how that’s managed. Instead of going down that path just setup aliases which are simple folders that represent where you want the data to go or read from. I use them quite often.

All my clients which are students & Pro music & video production use a dual drive setup in one form or another. Most of the students who use older Intel iMac’s leverage the blade SSD and SATA SSD as I described. It offers the best performance and most have a 1TB blade drive.


The allocation of your files is mostly at the setup where you place the Apps and using aliases. But only needed for your active projects just to make navigation easier (more)

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(cont) The OS pick list always remembers where last for the given App, basically this is not a problem under macOS.


As an example my own 2013 Mac Pro has a 2TB Blade SSD and I use an external SSD RAID box as my second drive, as a photographer who works with ultra large images used in dioramas and theater back drops I needed this level of gear. But your workflow needs are likely very different.

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Really appreciate your help and many thanks indeed!

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