Having got back to where I had been before the drive failed I was happy with going back to work on the iMac. However I was suspicious that the drive might fail again. I kept regular backups of files and photos, but I did have an expectation that the drive might fail again.
On Saturday it did just that. I was using the iMac to sort out some train tickets and other tickets when it just froze. Nothing was working, so I switched it off at the back and when I switched it back on I was rather downhearted, but not really surprised, to see the prohibitory symbol.
I booted into Recovery mode (hold down the Command and R keys when turning on and release once you see the Apple logo or a spinning globe). I ran disk utility which confirmed the Fusion Drive had failed. The SDD was working fine, but the (mechanical) hard drive had failed. A Fusion Drive us made up of an SDD drive and a standard hard disk drive combined to look like a single drive under OS X.
Luckily I hadn’t lost any data, but wasn’t sure what to do next.
I did reformat the SDD and installed OS X onto that (and even upgraded to Big Sur). The speed was very impressive and to be honest part of me did think about leaving it like this. However this wasn’t a practical long term solution as the iMac would just randomly reboot for no reason. Certainly couldn’t use the iMac for anything productive.
I did look into fixing the iMac myself, but in the end booked it into the Cribbs Causeway Apple Store Genius Bar for an appointment. The 2014 iMac counts as vintage technology (as it is just under their seven year limit) and isn’t quite obsolete, yet!