Change the paths below as appropriate.

sudo umount /dev/vg0/lv0
sudo lvchange -an /dev/vg0/lv0
sudo vgchange -an /dev/vg0
# Actually spin down the disks. Do this for each physical disk.
sudo udisksctl power-off -b /dev/disk/by-id/lvm-pv-uuid-FOO
sudo udisksctl power-off -b /dev/disk/by-id/lvm-pv-uuid-BAR