iMac with 2 hard drives

Hello, lilleshall.

This new (to you) iMac is going to be a little bit of a challenge to properly setup and use as far as file management goes.

Your wife's user account will remain on the startup drive "Macintosh HD". But you want her music, photos and documents to live on FC (FireCuda). Okay. You'll have to tell iPhotos and iTunes apps to locate their libraries on FC. Easy enough, but a little bit of a process.

You'll also have to create a folder on FC for her docs etc and she'll have to remember to use that when she creates and saves stuff.

IMHO, it would be easiest to clone the current startup drive to the FireCuda and use that as the main drive. I think the Macintosh HD boot drive, being flash storage, is faster than the FC, but the data management will be much easier if the OS and user files are on the same drive.

Optionally, since the iTunes and iPhoto libraries are often the biggest consumers of storage space, just locate those on FC and leave the OS and the rest of her files on Macintosh HD.

The easiest, dead simple way to clone the startup drive to the FC drive is to use CarbonCopyCloner from > bombich.com. The trial version is all you need for this one task. Since you are running High Sierra, you need to download the older CCC5, not the newest version 6.

CCC will copy the data and the macOS making the clone bootable. After the task is complete, you will also have the option to install the recovery partition to the new startup drive. You should do that as it would be useful in case of future trouble. The CCC website has easy to find help if you have questions about the software or process.

Yes, disabling the current startup drive would simplify things, but there is no easy way to do that permanently. The drive would have to be removed.

Once you have FC setup as the startup drive, you can simply ignore the smaller drive. I admit it seems a waste of an apparently perfectly good drive, but for casual users there's no need to complicate things by splitting the locations of user files. And I suspect the 1TB capacity of FC will be more than enough for your wife for some time, unless she's a power user of some sort.

When the cloning is complete, go to System Preferences > Startup Disk. Unlock the panel and then select FC as the startup disk and close the panel. The next time you restart your Mac it will launch from the new startup selection.

As a user tip, I'd also advise you to rename the drives. Rename the small drive first, something like "iMac SSD", and then for the sake of clarity and standards, change the name of FC to "Macintosh HD".

Yes, you can eject it. Unfortunately, it will show up again on the desktop the next time you restart the Mac.

You can keep that from happening by clicking Finder > Preferences > General and uncheck the box for Show Hard Disks on the desktop.

You're welcome.

Happy to know you sorted this out, my friend. 🙂