Logical Volume Manager (LVM) appears to be the correct label/name of the filesystem you are referencing; based on vol000. Look for the LVM-HOWTO ignoring non-FC3 references - on Linux Documentation Project and other sites.
Also: refer toi 'man lvm' or 'info lvm' for discussion of most of the commands.
LVM basically allows you treat all physical hard drives as a collection of space. Space that is sub-divided into logical volumes; where volumes can be mounted as a part of your normal linux file tree. Because of this logical connection to physical space - there are commands that allow you to grow the size of the logical without caring what physical drive it lands on).
This can be handy if your creating a dedicated server linux box. I found it to be a real pain to use for everyday workstation stuff and removed it. I now use XFS as my file system.
LVM Example: Typical Desktop System
Mountpoint, volume-name, vol-size, fs-type, partition
/boot, NA, partition-size: 256M, ext3, hda1
/swap, NA, partition-size: 2GB, swap, hda2
/, vol000, 20GB, ext3, lvm-assigned
/home, vol001, 30GB, ext3, lvm-assigned
lvm-space: (72GB total)
hda3 = 35GB
hdb1 = 37GB
(two 40GB drives installed)
20GB would be free for expansion of current volumes -vol000 | vol001. Or the creation of a new volume when needed; say '/var/local' or '/usr/local'
Thats more than I planned to say - but I hope it helps.