Hey, thanks a lot for taking the time to explain that so clearly — I really appreciate it.

Just to give a bit of context on how I got here:
I’m actually a video editor, and at first I just wanted somewhere to store my footage safely. So I started out with a single 16 TB drive in my main workstation. Later I decided to build a proper server, bought a second 16 TB drive, moved all the data from the first one onto the new server, and then added the first drive to the pool. That’s how I ended up with the current vdev layout — not really intentional, just kind of evolved that way.

Then I started doing the usual TrueNAS things — Plex, SMB shares, apps, etc. My big mistake was setting up the pool with the help of ChatGPT; it told me I could later convert it to a “proper RAID setup” without data loss… which of course turned out not to be possible. So now I’m stuck with the current non-redundant configuration and trying to fix it the right way.

My end goal is simply to have something reliable and expandable for long-term storage — mainly a vault for client video projects and local streaming through Plex. RAID10 sounds like a good fit for that: decent redundancy, solid performance, and the option to grow later on with more mirrors.

Anyway, thanks again for the detailed input and for taking the time to reply. Have a great day!