I don't do any of the actual server infra so I don't have all the details.
The btrfs raid setup is standardized across all our infra and can be found on ansible.
https://gitlab.archlinux.org/archlinux/infrastructure/-/blob...
https://gitlab.archlinux.org/archlinux/infrastructure/-/blob...
From what I can tell it's been working fine and behaves nicely with failing disks.