Adding a LVM Cinder Volume
mkfs.ext /dev/md0
mkdir /cinder-volumes
mount /dev/md0 /cinder-volumes
dd if=/dev/zero of=/cinder-volumes/cinder-volumes bs=1 count=0 seek=3950G
losetup /dev/loop2 /cinder-volumes
pvcreate /dev/loop2
vgcreate cinder-volumes /dev/loop2
Double check your work with pvdisplay and vgdisplay: