I rebuilt a NAS onto a mirrored encrypted root: two SSDs, mdadm RAID1, LUKS2 on top, LVM inside. That layout is well-trodden — it’s what the Debian and Ubuntu Server installers produce when you ask for software RAID plus encryption, and the reasoning for putting RAID below LUKS is sound. You encrypt once instead of twice, resync traffic is ciphertext, and rebuilds work on raw blocks below the crypto layer. ...
I was rebuilding the boot disk of a NAS running Ubuntu 24.04 — kernel 6.8 — and doing the work from an Ubuntu 26.04 live USB, because that’s what I had on the Ventoy stick. This felt fine. A newer rescue environment is usually a better rescue environment: more recent tooling, drivers for newer hardware, fewer bugs. The plan was a mirrored encrypted root: GPT, mdadm RAID1 across two SSDs, LUKS2 on top, LVM inside. I created the array degraded on the new disk, put LUKS2 on it, made the volume group, copied 262 GB of root filesystem across, set up systemd-boot, and rebooted. ...