A wrap-up of what I ended up doing:

• Replaced the bare metal Ubuntu with Proxmox. Cool cool. It can do the same stuff but easier / comes with a lot of hints for best practices. Guess I’m a datacenter admin now
• Wiped the 2x960GB SSD pool and re-created it with ZFS native encryption
• Made a TrueNAS Scale VM, passed through the SSD pool disks, shared the datasets with NFS and made snapshot policies
• Mounted the NFS on the Ubuntu VM running my data related services and moved the docker bind mounts to that folder
• Bought a 1Gbps Intel network card to use instead of the onboard Realtek and maxed out the host memory to 16GB for good measure

I have achieved:

• 15min RPO for my data (as it sits on the NFS mount, which is auto-snapshotted in TrueNAS)
• Encryption at rest (ZFS native)

I have not achieved (yet…):

• Key fetch on boot. Now if the host machine boots I have to log in to TrueNAS to key in the ZFS passphrase. I will have to make some custom script for this anyway I guess to make it adapt to the situation as key fetching on boot is a paid feature in TrueNAS but it just makes managing the storage a bit easier so I wanna use it now. Disabled auto start on boot for the services VM that depends on the NFS share, so I’ll just go kick it up manually after unlocking the pool in TrueNAS.

Quite happy with the setup so far. Looking to automate actual backups next, but this is starting to take shape. Building the confidence to use this for my actual phone backups, among other things.

Really good to know. Planned to keep using very mainstream LTS versions anyway, but this solidifies the decision. Maybe on a laptop I’ll install something more experimental but that’s then throwaway style.

I guess I’ll give it a spin. There seems to be a big community around it. I initially thought I might migrate later so keeping the host OS layer as thin as possible. Ubuntu was mainly an easy start as I was familiar with it from before and the spirit in this initiative is DIY over framework - but if there’s a widely used solution for exactly this… Yeah.

Right, thanks for the heads up! On the desktops I have simply installed zfs as root via the Ubuntu 24.04 installer. Then, as the option was not available in the server variant I started to think maybe that is not something that should be done :p

Aight thank you so much, confirms I’m on the right path! This clarifies a lot, I’ll keep the ext4 boot drive :)

Right, so my aversion to live backups comes initially from Louis Rossmann’s guide on the FUTO wiki where he mentions it’s non trivial to reliably snapshot a running system. After a lot of looking elsewhere as well I haven’t gotten much hints that it would be bad advice and I want to err on the side of caution anyway. The hypervisor is QEMU/KVM so in theory it should be able to do live snapshots afaik. But I’m not familiar enough with the consistency guarantees to fully trust it. I don’t wanna wake up one day to a server crash and trying to mount the backed up qcow2 in a new system and suddenly it wouldn’t work and I just lost data.

It won’t matter though as I’ll just place all the important data on the zpool and back that up frequently as a simple data store. The VMs can keep doing their nightly shutdown and snapshot thing.

This is what I’m doing currently, but it’s not really feasible to have the services shut down hourly for snapshots. This is indeed why I started looking towards filesystem-level snapshotting Obviously I will have other types of backups as well, I’m simply looking to have the on-the-fly immutable snapshot capability here somehow.

Thanks! Can I ask what is your setup like? ZFS on bare metal? Do you have VMs?

Fair about the SSD life. How would you go about achieving the frequent backups without zfs? I wouldn’t want to implement it separately for every app I use, though I’m open to it if this doesn’t work out.

I’ll easily buy more memory if needed, the box now has 8GB and isn’t struggling in any way.