Oh, forgot to mention: striping in ZFS will use the capacity of the smallest drive. It sounds like you have a 1TB drive and a 4TB drive, so striping would give you access to 2TB at most.

Losing one drive in a striped pool with no redundancy means the entire pool is shot. Restoration from your HDDs may take a very long time, on top of data loss between the time of failure and your last snapshot. Striping without redundancy is fast, but dangerous.

This may work at first, and maybe you really do have a use case where this kind of failure is tolerable. However, in my experience, data is precious more often than it isn’t. Over time, you’re more likely to find use cases where the loss of the pool will be frustrating at best, and devastating at worst.

If you’re not using any redundancy, I would create separate pools so each drive can fail independently. You’ll have all 5TB of storage, but not contiguously. That at least constrains the failure modes you’re likely to run into.

If you are striping with redundancy (e.g., RAID-Z1), which I would highly recommend, you can lose a drive and not lose any data. That would take at least 3 equally-sized drives though, and you’d only be able to use the capacity of 2 of them.

It’s really more of a proxy setup that I’m looking for. With thunderbird, you can get what I’m describing for a single client. But if I want to have access to those emails from several clients, there needs to be a shared server to access.

docker-mbsync might be a component I could use, but doesn’t sound like there’s a ready-made solution for this today.

Yeah, they are ideally the same mailbox. I’d like a similar experience to Gmail, but with all the emails rehomed to my server.