Apparently when I upgraded to Sierra I enabled iCloud drive storage for my documents.
Recently, when searching for some files which I've had for months/years now, I discovered that they were no longer on my computer, but instead "in the cloud". Notice the devilish iCloud symbols in the screenshot:
This is extremely distressing - I was not aware that iCloud drive storage would actually DELETE my files from my computer. Honestly this is ludicrous that this would happen, and I suspect it's probably screwing with my other syncing software (Sugarsync).
Now, I want to disable it, but it I've heard to that disabling it will delete all the local files from my computer. Thus, I'd like to back up all my files, but how can I tell which files actually exist on my computer and which files are "fake placeholders" for the real files which only exist now on iCloud?
Even if a particular file doesn't have the little iCloud symbol as in the linked screenshot above, do I really have to examine every single file in every single subfolder of Documents/Desktop to ensure that it's real? For the last hour I've been clicking that iCloud symbol, which appears to download the real files from iCloud, but I'm not sure if I've finally got them all. Is there a way to check file there are any files which haven't been downloaded?
EDIT: Okay, even after clicking the iCloud button on all my documents, which I thought would download them to my computer, after disabling iCloud storage of Desktop+Documents folder in settings, it STILL DELETED ALL MY DOCUMENTS (Why in god's name would Apple do this to their customers data?). Now I'm trying to move them from iCloud to my local drive, and for the last 9 minutes now I've had a dialog box saying "Preparing to move to 'Documents'..." with no sign of progress. At this point I'm too scared to cancel it, or even bring my computer to an Apple store for fear of losing everything.
EDIT 2: It's been over 20 minutes now and the process seems to have hanged. It's managed to move 3 small folders (even though it's still saying "Preparing to move to 'Documents'"), and a few files, but hasn't moved anything in about 10 minutes.