My understanding is that Garage is not opinionated and could easily have worked without ZFS. I installed ZFS in Ubuntu, and then later installed Garage.

As for the ZFS setup, I kept it simple and did RAID5/raidz1. I'm no expert in that, and have been starting to think about it again as the pool approaches 33% full.

I saw this comment in another thread here that sounded interesting as well by magicalhippo: "I've been using ZFS for quite a while, and I had a realization some time ago that for a lot of data, I could tolerate a few hours worth of loss. So instead of a mirror, I've set up two separate one-disk pools, with automatic snapshots of the primary pool every few hours, which are then zfs send/recv to the other pool."

This caught my attention as it matches my usecase well. My original idea was that RAID5 would be good incase a HD fails, and that I would replicate the setup at another location, but the overall costs (~$1k USD) are enough that I haven't done that yet.