What is an LVM?
 

somebody tell me what an LVM is?

What are the advantages of using an LVM?

Check out, for example, http://linux.org.mt/article/lvm (That from a quick google of "logical volume").

LVM = Logical Volume Management (Manager?)
A way to combine multiple partitions, drives, etc. to act as one volume

http://www.tldp.org/HOWTO/LVM-HOWTO/

Here's the "big picture" in a nutshell
 

One word that, I believe, IBM originally coined was the concept of a storage pool. This is, simply, "a place where you can put files." Notez vous...

• It does not say anything about which disk-volumes may contain the information.
• It does not even imply that a single file must reside wholly upon any particular volume.
• It does not imply that only one physical copy of a particular file may exist.
• The concept is intentionally abstracted from the original concept that "a mount-point equals a physical disk and a file lives there."

This is what enables a data-center to liberate itself from the "one drive, per drive" mentality and to reasonably support what might be a disk-farm of hundreds of spindles, and to manage that storage space effectively on an on-going basis. Depending on the implementation, it also presents us with the opportunity of making part of the management-problem into something that a computer can help us to solve and manage.