root# lvcreate -s -L 200g -n snap_home_lv /dev/mapper/sara_vg-home_lv
  Volume group "mapper" doesn't exist

root# lvcreate -s -L 200g -n snap_home_lv /dev/sara_vg/home_lv
  Logical volume "snap_home_lv" created

root# ls -l /dev/mapper/sara_vg-home_lv
brw-------  1 root root 254, 2 Mar  7 20:51 /dev/mapper/sara_vg-home_lv

root# ls -l /dev/sara_vg/home_lv
lrwxrwxrwx  1 root root 27 Mar 17 14:18 /dev/sara_vg/home_lv -> /dev/mapper/sara_vg-home_lv

root# ls -lL /dev/sara_vg/home_lv
brw-------  1 root root 254, 2 Mar  7 20:51 /dev/sara_vg/home_lv

root# ln -s /dev/sara_vg /dev/blah

root# lvcreate -s -L 200g -n snap_home_lv /dev/blah/home_lv
  Volume group "blah" doesn't exist