Chosen Solution

Hello everyone, I currently have a 2019 iMac 27" with a Fusion Drive. One day it quit on me and now I cannot boot at all, and only see a “circle with slash” error. I’ve gone into recovery and Disk Utility does not properly detect my HDD from what it looks like. I’ve also tried to reconnect the fusion drives but it provides an error saying that I only have one drive. After some research, I have come across the below solutions, Replace the internal HDD with a large SSD. This is my preferred solution, but I would also like to disable the SSD cache drive. I believe having just the one SSD will be more than enough for me. Is it possible to disable the SSD cache without physically removing it?Booting from an external drive. Second preferred method. I don’t mind having an external connected. Would a USB3+SSD combo suffice for this or should I be looking at Thunderbolt+NVMe? Also, would the (possibly) 2 failing internal drives have any affects on my system?Replacing the HDD and SSD. If I have to I can go this route. Though if I did this, could I JUST replace the SSD blade with a larger capacity one, and have that do all of the work? It would at least save me some effort and cost to buying 2 drives and also various adapter kits, etc Any help is greatly appreciated! Please let me know if there’s any more information I can provide. I’m currently toying with recovery mode, and am going to try installing macOS onto an extra external SSD that I have, just to see how it goes or if it’s even possible

1 - Sadly, you will need to pull the blade SSD as it gets in the way trying to sync up withe the new drive which you don’t want to do here. 2 - Think how you use you car, just motoring around town with the kids or driving great distances on the Autobahn. Very different use cases! For most the internal drive is the better as USB is on the slow side Vs SATA and PCI is the fastest internal, with Thunderbolt3 with a RAIDed drive set the fastest. Not sure I follow you here with two failed drives. A Fusion Drive set is seen as one drive so if you physically loose one drive the second is useless. That is what dual independent drives are better and using the better technology for the function here using a SSD for the boot drive and Applications and free space for virtual ram, caching and scratch space if the app uses it. Then use the HHD as your data drive holding what’s important. Of coarse backing up as well to an external drive as well to be fully safe. 3 - Sure getting a bigger blade SSD also works. But depending on your workflow it may not be the best option! Let’s look at this in a physical model… You have a chalkboard and your have a single sheet of paper how many times can you write on the chalkboard wiping off once you’ve filled the board? Now how many times can you erase the paper after filling it? Clearly the chalkboard is infinite! The sheet of paper only has so many times before it’s either torn or just not readable! This is the difference between a HDD and a SSD a HDD can be written to many more times than a SSD, barring a physical drive failure. Conclusion: What is your usage of the system will make a big difference on what it the best option for you. Just like the given car you drive :eats your usage need.