About IDMS
Features:

I) LVM (Logical Volume Manager) featuring...

1. Combining of disk drives into physical volumes (called a PV)

2. Combining of PV's into volume groups (called VG's), which you could think of as being the basic storage pool.

3. Combining of VG's into physical extents (called PE's)

4. Some or all PE's of this VG can be allocated into a logical volume (called an LV) or LV's in units called logical extents (called LE's). Each LE is mapped to a corrosponding PE. LE's and PE's are equal in size. So in the end LG's are nothing but a normal partition with hundreds, even thousands of more features and options.