I want to completely stop my internal Fusion drive from powering up, since I no longer use it and it is very noisy.
My late 2012 27” iMac came with a Fusion drive, which has long since stopped working correctly. In fact, I long ago began using an external Thunderbolt drive for macOS and documents; now using Mojave 10.14.6.
I no longer use the internal drive(s). I also disassociated the two parts of the Fusion drive and reformatted them as 2 separate drives, one becoming a 120GB SSD, and the other a larger hard disk drive. The Fusion drive is labeled as follows: “Type: SATA Internal Physical Volume” “Device: disk1s2”. The SSD part of the disk still usually mounts. The SATA hard drive only mounts occasionally at start-up, and often dismounts itself after unsuccessfully getting stuck reading. (It will show up for a while sometimes and start to show the hierarchy, before shutting down.)
I prefer not to physically open the iMac to remove the drive (apparently, it's not a simple operation).
My big problem is the noise from the internal disk trying to spin.
I would like to completely disable the internal Fusion drive. I see some suggestions online from many years ago, and many previous versions of macOS, using Terminal commands, but am unsure if they would still work, and I don’t have much experience.
Suggestions? (This Mac has run 24 hours a day since 2012. I’m not tossing it. It still works great.)