Perhaps I can assist some with answers based on personal testing...
I first created a backup of all of my documents on a separate external hard drive (left unplugged for good measure from my iMac for the duration of the test) in case things went horribly wrong then I began the test performing the following steps:
1: I upgraded OS X EL Cap on my iMac to macOS Sierra and immediately activated Desktop and Documents storage in iCloud.
Within an hour or so my Documents folder and all of its contents moved (or duplicated itself) to iCloud (along with the Docs folder itself moving under the iCloud parent folder in Finder's folder hierarchy.)
2. I then decided to test the offline availability of my documents with wifi turned off (and a reboot just to make sure my iMac was truly offline) and the result was all of my actual documents in my Documents folder were found to be intact and editable on my local hard drive during this offline state.
3. While in this offline state, I made a simple modification to one of my documents stored in my Documents folder on my iMac, rebooted and immediately got the machine back online.
I quickly opened Finder, navigated to the Document's subfolder that stored the test document I had modified and saw an upload arrow indicating "synchronization" was taking place with the copy in iCloud. It completed in less than a minute with my average upload speed of 6Mbs provided by my ISP plan. After the upload completed I verified the modified version of the document was intact in my cloud account and was now indeed the same version recognized by all of my other Apple devices connected to iCloud.
4. I then went one step further and wiped MacOS using Internet Recovery to test what manual document recovery steps might be required with a catastrophic failure. After downloading and installing my factory supplied copy of Yosemite on my 2014 iMac, I immediately upgraded to macOS Sierra via the app store ( and with none of my documents put back in place on this factory restored image of Yosemite prior to the Sierra upgrade) and reactivated the Desktop and Documents iCloud storage feature during Sierra setup.
As soon as my desktop loaded I checked Finder and noticed iCloud synchronization (for lack of a better word) had begun as indicated by the Finder>iCloud icon's black progress bar sweeping clock-wise like the hands on the face of a clock as a copy of my cloud's Document folder was being restored to my iMac and without my intervention.
Whatever system Apple uses to make this process happen reliably and under catastrophic failure conditions has been very well thought out. This iMac was the "master" or my first machine to utilize this feature and my MB Air was the second machine that I activated the feature on a week before this test. Even after an Internet Recovery with my iMac, their system immediately recognized my iMac was previously the Master and retained the hierarchy of both machines with my MBA's Document folder retained as a child folder within my iMac's Document folder as they stated would be the case once the "copy" of Documents downloaded or synchronized with my local drive.
5. My final test was simply a single document recovery attempt from a Time Machine snapshot which worked exactly as you'd expect whether recovering a lost document or overwriting an existing document with an older version (whereupon you are prompted to keep one or both versions along with where you want to store it via the familiar shrunken Finder window).
Apple - I am impressed.
Stephen Bromberg
Level 1
(10 points)
