Chapter 1. What is LVM?

LVM is a Logical Volume Manager for the Linux operating system.
There are now two version of LVM for Linux:

LVM 2 - The latest and greatest version of LVM for Linux.

LVM 2 is almost completely backward compatible with
volumes created with LVM 1. The exception to this is
snapshots (You must remove snapshot volumes before
upgrading to LVM 2)

LVM 2 uses the device mapper kernel driver. Device mapper
support is in the 2.6 kernel tree and there are patches
available for current 2.4 kernels.

LVM 1 - The version that is in the 2.4 series kernel,

LVM 1 is a mature product that has been considered stable
for a couple of years. The kernel driver for LVM 1 is
included in the 2.4 series kernels, but this does not mean
that your 2.4.x kernel is up to date with the latest
version of LVM. Look at the README
for the latest information about which kernels have the
current code in them.