by dabrahams » Fri Jan 03, 2020 3:57 pm 
			
			After rebooting the machine, BB started doing its thing, and it does appear to be including the 2TB of ZFS data that's mounted under /Users/Shared in the backup.  So, yes, all you need to do to get Backblaze to back up your ZFS is to give it a mount point that's not under /Volumes.