ubuntu@juju-devel3-machine-29:~$ df -h
Filesystem                          Size  Used Avail Use% Mounted on
udev                                2.0G   12K  2.0G   1% /dev
tmpfs                               396M  336K  395M   1% /run
/dev/disk/by-label/cloudimg-rootfs   40G  1.4G   37G   4% /
none                                4.0K     0  4.0K   0% /sys/fs/cgroup
none                                5.0M     0  5.0M   0% /run/lock
none                                2.0G     0  2.0G   0% /run/shm
none                                100M     0  100M   0% /run/user
ubuntu@juju-devel3-machine-29:~$ sudo lsof -F | grep vdb
cjbd2/vdb-8
ubuntu@juju-devel3-machine-29:~$