Adding a LVM Cinder Volume

 

mkfs.ext /dev/md0
mkdir /cinder-volumesvol
mount /dev/md0 /cinder-volumes
dd if=/dev/zero of=/cinder-volumes/cinder-volumesvol bs=1 count=0 seek=3950G
losetup /dev/loop2 /cinder-volumesvol
pvcreate /dev/loop2
vgcreate cinder-volumesvol /dev/loop2

Double check your work with pvdisplay and vgdisplay: