Understanding iCloud+ storage and Mac mini SSD usage

I'll add a couple of things to Phil0124's response, because there's a lot here.

First, iCloud isn't a backup, and I'm not sure I would trust Dropbox as a backup, either. So you need to get all that data onto a local external drive (or two!)

You can put more stuff into iCloud Drive than you have on your internal drive by using "Optimize Storage." This keeps a pointer on your desktop so you can double click on the icon, and the Mac will go out to iCloud.com and grab the file. But you can do this same thing much easier by just getting an external drive. And if files which are not physically on your drive (or on your external drive,) then they can't be backed up. This is a giant limitation.

The purpose of iCloud Drive isn't to store extra stuff-- it's to make some of your most used files available on other devices, like on your phone or on your iPad or on another Mac. It that's not want you want, then iCloud Drive may not be the right choice.

You can never have too much storage on your Mac, but since you're getting one that's non-portable, using a fast external drive is pretty close, and it's half the price (or something like that.) So you could have two drives for the same price! External drives are a little harder to use with a portable MacBook.

Understanding iCloud Drive - Apple Community

PhilJansseune wrote:

I am about to buy a Mac Mini that has a 2Tb SSD. My 'live' graphic design work is is already on iCloud+ (or iCloud Drive as it used to be called)

No, it still called iCloud Drive. iCloud+ refers to the actual storage space you pay for not what you use it for.

iCloud Drive is just one of the many things that uses the iCloud+ storage.

Other items that use iCloud+ storage include iCloud Photo Library, Notes, Contacts, Email, Backups etc... none of which are on iCloud Drive.

and is set at 2Tb although I only use just over half of it at the moment. However I have a lot of 'archived' work on Dropbox (approx 1.5Tb) that I download occasionally if I need to retrieve old files. Dropbox has never been a good solution as I get the zero file size option that many others experience so the links refuse to work, but as a storage option it's reliable and cheap. It seems prudent to increase my iCloud+ storage to 6Tb as my storage requirements are only going to increase BUT... will my 2Tb SSD fill up and leave some of my iCloud+ storage unused, or doesn't it work like that?

Technically yes. You can only have 2TB of data locally, so no more than that can sync to iCloud from the computer, which would leave the rest unused unless you have some other device, that is also using iCloud+ storage and salving content and data to it separately to the Mac.

Should I upgrade to a 4Tb SSD instead which will better utilise my 6Tb storage or is that just buying extra SSD space for applications etc which aren't going to be hosted on the iCloud+ space anyway?

It will be used for both things. Local storage is used for Apps and system data that is not synced to iCloud, but would also be used for other things like Photos and Files that do get synced to iCloud, so yes, its always good to have more local storage.

PhilJansseune wrote: I've lost work on several occasions when individual drives have failed

Me, too. That's why I use two drives for Time Machine backups-- one is a fast SSD, and the other spins. And I use iCloud to help make files available on other devices. I don't use "Optimize Storage" on my Mac, because then files can't be backed up. So I rely on iCloud Drive for working files that I want to see on my phone or iPad or other Mac. (I also have old, slow, HDDs for less timely backups.)

If Apple servers crash

This is not likely. But iCloud does automatic copies. That means that it copies mistakes. I'm not as worried about Apple messing up my files as I am about it replacing documents with my flubs.

Really old work still goes on to DVD

I went back to my DVD (and CD) backups of pictures from past decades, and I was surprised by the number of corrupted files. Recovery was pretty painful.

I also use Drive to access my work from a laptop so I can pick up my work seamlessly while travelling and it works a treat. This has a 2Tb SSD onboard.

Exactly what iCloud is for!