Hi,
Same error here with a Dell PE R620 server, with H710p Raid controller, and 8 500 Go NearLine SAS drives in Raid 10.
At boot, it says 'no controller found', then, 'LVM volume not found', and 'volume pve-root not found'.
In the rescue shell (busybox), 'lvm vgchange -a -y' then Ctrl-D...