TL;DR: This is what I did to recover a drive (raid array mirrored) from QNAP hardware failure: apt install mdadm lvm2 lvscan vgscan vgchange -ay vg288 lvs mkdir /mnt/recover mount /dev/vg288/lv1 /mnt/recover -o ro,user cp -R /mnt/recover/share_folder /backup (where vg288 is the volume listed in vgscan that your raid is on)
