The Trouble With Enabling the Desktop & Documents Option in iCloud Drive.
Apple first introduced the Desktop and Documents option to iCloud drive in Mac OS 10.12 Sierra. In fact, it is a PRE-SELECTED option is defaulted to ON during the initial installation or update process.
The files in the Desktop and Documents folder are synced to your iCloud account and made available on your iOS devices and other Macs In addition to the traditional categories (phots, contacts, calendars, notes, etc.). Apple notes in a support document how the Desktop and Documents option frees up storage space: “When storage space is needed, only the files you recently opened are kept on your Mac, so that you can easily work offline. Files that are stored only in the cloud show a download icon, which you can double-click to download the original file.”
However, there is a glaring downside.
You have only a single copy of your files if they’re removed from all your connected Macs and only stored in iCloud. Therefore you’re relying on Apple and its data centers and redundancy for every copy of the file, because
if a file isn’t stored locally on your Mac you have no way of backing it up.
The best practice for file backup is to have at least three backups of them (two different kinds of media/location and one offsite). iCloud’s Desktop and Documents falls short here.
Apple should have integrated this with Time Machine/hosted backup services. If dome properly, the iCloud sync service wouldn’t delete a local copy of the file synced to iCloud until a recent Time Machine backup of the file is made allowing for both a local and an offsite backup. When using a program like Crashplan to back up offsite, it could mark files as being archived and readable by iCloud sync
Apple also requires you to pay monthly for storage above the 5GB that is included free with iCloud. If you stop paying, you could wind up either having to download all those synced-and-removed files—and lack local storage to do so—or lose access altogether.
—-
As a result, HB Technology Solutions strongly recommends de-deselecting the option to start icloud Desktops and Documents during the installation of OS X 10.12. Also avoid turning it ON manually from the Options button next to iCloud Drive in the iCloud system preference.
Continue using a local drive and hosted backup service for backups rather than a mistaken reliance upon and incomplete solution from Apple that puts too many eggs in one basket.