For cost reasons, I’m moving all of my data from Dropbox over to iCloud (I really like the Dropbox service, but this is really about dollars given the amount of storage I need).
With Dropbox, you create a Dropbox folder (in this case on my Drobo) and whatever is in the Dropbox folder gets synched with Dropbox.
iCloud? I can drop it into the iCloud Drive, but how do I also get the files on my NAS? I want it in both places because iCloud is not a backup service, just a synch service.
TIA…Scot
The easiest way to do this is probably to run something like Carbon Copy Cloner and clone your iCloud Drive folder to the Drobo.
I’m not sure if you’re asking if it’s possible to replicate/sync your iCloud local folder to your Drobo, or if you want to move the local copy of the files so that they’re stored on the Drobo instead of your computer’s local drive.
Hazel can do the, I use it to backup Final Cut projects to an external drive. Whenever there is a modification or addition to the directory Hazel automatically syncs.
I got the rules from https://www.noodlesoft.com/forums/viewtopic.php?f=4&t=1593#p6500
Be aware that unlike Dropbox, not everything in iCloud is accessible via the “iCloud Drive” folder. Music, Photos, and storage for many individual apps, all synced via iCloud, is found elsewhere on your Mac.
Ideally, I’d like to move the local copy of the files so they are stored on the Drobo instead of on the Documents folder on my local hard drive. Looks like I won’t be able to do that, though.
I don’t have Caron Copy Cloner, but see where you are going with this. I do have Hazel, so will take a look at Rob’s info below. Thanks for the reply.
Yup! I’m aware of that.
Rob, I have Hazel, so I’ll take a look at the instructions. If I can’t directly move the local drive Documents folder over to the Drobo, this would at least give me a second place to store the files and do it automatically. Thanks for the response.
I wonder if you could move the directory over to the Drobo and then symlink it back to its default location. (I don’t think it’s wise, but I’m wondering if it can be done).
Otherwise, cron + rsync would be a free alternative for such a simple task, if you’re at all willing to take advantage of the Unix underpinnings of macOS 
Do you want a backup on you NAS or have the files constantly mirrored on your NAS? Depending on the use case: Resilio Sync, Carbon Copy,…
I’ve used symbolic links to store files on an external drive and have them appear to the system as local. That was how I “stored” 400+ GB on an 128GB MacBook Air. A symlink is like a alias, but you have to create it with a terminal command:
ln -s /path/to/file /path/to/symlink
For example: ln -s /Volumes/Drobo/Docs/ /Volumes/MacHardDrive/Users/Wayne/Documents
Once created files that you place in Drobo/Doc folder will appear in your /Users/Scotk9jy/Documents folder
If you want to try, I suggest you google symbolic links and review the command, then do some testing with a thumb drive rather than your drobo. Here’s one link explaining them. https://www.howtogeek.com/297721/how-to-create-and-use-symbolic-links-aka-symlinks-on-a-mac/
This works in most instances, but iCloud buries its files in /Users/Scotk9jy/Library/Mobile\ Documents/ YMMV
Ou could try resilio sync?