On the storage node:

root@storage-01:~ # fdisk -l /dev/mapper/cinder--std-volume--542d4bfc--7b64--479e--8eda--5bb929f1c8ed
Disk /dev/mapper/cinder--std-volume--542d4bfc--7b64--479e--8eda--5bb929f1c8ed: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe534536a

Device                                                                         Boot Start      End  Sectors Size Id Type
/dev/mapper/cinder--std-volume--542d4bfc--7b64--479e--8eda--5bb929f1c8ed-part1 *     2048 41943006 41940959  20G 83 Linux

root@storage-01:~ # lvdisplay 
  --- Logical volume ---
  LV Path                /dev/cinder-std/volume-542d4bfc-7b64-479e-8eda-5bb929f1c8ed
  LV Name                volume-542d4bfc-7b64-479e-8eda-5bb929f1c8ed
  VG Name                cinder-std
  LV UUID                9mjEIH-RjHt-Xu9r-apch-Ncf1-iAow-voPBGX
  LV Write Access        read/write
  LV Creation host, time storage-01, 2017-04-25 15:33:37 -0600
  LV Status              available
  # open                 1
  LV Size                20.00 GiB
  Current LE             5120
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0



In the instance:

gentoo-base ~ # fdisk -l /dev/vda
Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe534536a

Device     Boot Start      End  Sectors Size Id Type
/dev/vda1  *     2048 41943006 41940959  20G 83 Linux

gentoo-base ~ # df -h
Filesystem      Size  Used Avail Use% Mounted on
udev             10M  4.0K   10M   1% /dev
/dev/vda1       2.8G  839M  1.8G  32% /
tmpfs           395M  264K  395M   1% /run
shm             2.0G     0  2.0G   0% /dev/shm
cgroup_root      10M     0   10M   0% /sys/fs/cgroup
/dev/sr0        482K  482K     0 100% /mnt/config