Can I use a ZFS ZEVO-managed USB hard disk for Time Machine backups and does it offer de-deduplication?
In the Time Machine pane of System Preferences, add any ZFS dataset. 

For the first backup to that dataset, the operating system will: 


create a sparse bundle disk image (….sparsebundle) at the root of that dataset
attach the image, after which you'll see a volume named Time Machine Backups.


For each subsequent backup to that dataset, the OS will: 


attach the image, after which you'll see the Time Machine Backups volume.


Time Machine routines with ZFS are similar or identical to the routines that apply when backing up to a device – such as an Apple Time Capsule – that uses AFP. 



How can one recover from TM after new/reinstallation? New OS installation knows nothing about ZFS to TM image is unreachable.