How to do disk mirroring on already running system?

[subjectx]

Greetings,

I made a poo poo when installing my server, forgot to turn on mirror on two nvme system drives.



Somehow Proxmox GUi shows 100gb of HD space(root). How do I check on which partition OS is installed? I guess its on /dev/nvme0n1p3.. How do I extend this partition to full remaining disk capacity?

Is there a way to create mirror with this second nvme without system downtime? Why does it say zfs_member?

 

[subjectx]

OK, I found this thread: https://forum.proxmox.com/threads/proxmox-zfs-mirror-install-with-one-disk-initially.53601/, is this still accurate?

I would like to have something like this, the correct config from my other server:


Is this possible without going from scratch?