Why LVM is required ?
LVM stands for Logical Volume Manager that provides logical volume management for the Linux kernel.Applications use a virtual storage, which is managed using a volume management software, a Logical Volume Manager.This LVM hides the details about where data is stored, on which actual hardware and where on that hardware, from the entire system. Volume management lets you edit the storage configuration without actually changing anything on the hardware side, and vice versa. By hiding the hardware details it completely separates hardware and software storage management, so that it is possible to change the hardware side without the software ever noticing, all during runtime.With LVM no application has to be stopped any more due to change in the storage configuration and that’s why the system uptime can be enhanced significantly.
Size of LVM partition can be extended and reduced by using the commands.