How To Create & Manage LVM in Linux

server1:~# fdisk -l
Disk /dev/sda: 85.8 GB, 85899345920 bytes
255 heads, 63 sectors/track, 10443 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

fdisk /dev/sda

server1:~# fdisk /dev/sda

The number of cylinders for this disk is set to 10443.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)

What is LVM In Linux

The logical volume manager allows you to create and manage the storage of your servers in a very useful manner; adding, removing, and resizing partitions on demand.

There several pieces of terminology that you'll need to understand to make the best use of LVM. The most important things you must know are:

• physical volumes
  • These are your physical disks, or disk partitions, such as /dev/hda or /dev/hdb1. These are what you'd be used to using when mounting/unmounting things. Using LVM we can combine multiple physical volumes into volume groups.
• volume groups
  • A volume group is comprised of real physical volumes, and is storage used to create logical volumes which you can create/resize/remove and use. You can consider a volume group as a "virtual partition" which is comprised of an arbitary number of physical volumes.
• logical volumes
  
  • These are the volumes that you'll ultimately end up mounting upon your system. They can be added, removed, and resized on the fly. Since these are contained in the volume groups they can be bigger than any single physical volume you might have.