Do files need to be on a Mac system drive to back up to iCloud?

[Ubele]

My wife and I currently each have a 2012 Mac mini and a Dropbox 1 TB plan ($9.99 per month each). We use iCloud for iTunes and Photos. One limitation of Dropbox is that files have to be stored on the system drive, because synchronization errors can occur if the Dropbox folder is on an external drive and the connection is lost temporarily. Our Mac minis each have big-enough Fusion drives to hold our entire Dropbox folders, so it's not an issue. I also have a MBP with 256 GB of storage, so I selectively sync the folders I need on that computer.

Since we're an all-Apple household, and Apple now offers a 2 TB iCloud plan for $9.99 per month that can be shared with family members, we're going to drop Dropbox and switch to iCloud. iTunes and Photos libraries can exist on an external drive. Is the same true for all the other types of files that we currently keep in our Dropbox folders? I couldn't find any information about this on Apple's site. The reason I ask is that we eventually will upgrade our Mac minis to new models. The price for Apple's storage upgrades is outrageous, and creating a Fusion drive is no longer an option. With Dropbox, if we want local copies of our files, we'd need to either spring for the 1 TB SSD upgrade (ouch) or boot from a significantly cheaper external SSD drive. If iCloud lets you back up files from an external drive, then a 128 GB (for my wife) and a 256 GB (for me) system drive would be plenty.

 

[ignatius345]

This is a great question. I got curious about it myself and found this thread. Seems inconclusive:

https://forums.macrumors.com/threads/icloud-documents-folder-moving-to-external.2108358/

One limitation of Dropbox is that files have to be stored on the system drive, because synchronization errors can occur if the Dropbox folder is on an external drive and the connection is lost temporarily.

The suggestion in the thread I linked to above is to make a symlink to the external drive's folder in your iCloud Drive folder (in effect making the Mac treat that external folder as being inside the iCloud Drive folder), but I suspect that you could run into issues as you do trying to use Dropbox that way. It just doesn't seem like iCloud Drive or Dropbox are designed to handle this. Maybe there's a way around it, though? Not sure.

One way you could work this without any hacking:

1) While you have your current machines with the big internal drives, sign up for that 2TB plan (I have it too, it's great)

2) move all your stuff from Dropbox to your iCloud Drive folder, let it sync. Verify it's synced by logging into the web-based iCloud Drive interface and making sure everything shows up there. (You should also see the files on your MBP, or at least the "placeholder" versions of them.)

3) When you migrate to your new Mac Minis, set them up for "Optimize Mac Storage" since they don't have room for everything. All your files are still uploaded to iCloud Drive, but your new Macs will just download stuff as you use it. It's a lot like Dropbox's Selective Sync, but with less manual control unfortunately.

If I was going this route, I'd probably put a step between 2 and 3 where I make sure I've got a spare backed-up copy of everything on an external drive before the Mac upgrade and before having all that data live only on Apple's iCloud servers. It's probably fine, but I'm personally big on having my own copies of my files.

 

[Ubele]

Thanks for the information, Ignatius. What's interesting about this is that the iTunes and Photos libraries can be put on an external drive--you just tell macOS where the libraries are that you want to be your system libraries. If the external drive becomes disconnected, macOS tells you that it can't find the Photos or iTunes library, and you just need to select it again. Any photos or songs that were uploaded from another device during the disconnection then get downloaded from iCloud. It seems like the same thing should be possible for the Documents folder. The difference, though, is that iTunes and Photos are managed libraries. You can't access your photos directly in Finder. You can access your iTunes media directly, but manipulating those files in Finder will confuse iTunes.

Anyway, thanks to Apple's price increases, a new Mac mini isn't the no-brainer purchase that our 2012 minis were in 2013 from the Apple Refurbished store. I immediately added third-party RAM, and, when the HDDs became annoying slow, I bought inexpensive SSDs and created Fusions drives. Aside from not being able to drive my 4K monitor at full resolution (but I can use my 2015 MBP for that), our 2012 minis are still adequate for our needs. As long as they keep chuggin' along, we might as well keep them for our local Documents libraries, even if we do upgrade to newer computers.

I wonder if Apple will discontinue the Fusion drive options when they next update the iMacs, and offer the same pricey SSD options that they do for the new minis. I'd expected Apple to offer Fusion drive options for the new minis--and, by extension, the ability to buy the lowest-storage option and create my own Fusion drive--but, alas, it was not to be.