Logical Volume Manager (Lvm); What Is Lvm - Red Hat ENTERPRISE LINUX 4 System Administration Manual

Chapter 7.

Logical Volume Manager (LVM)

7.1. What is LVM?

LVM is a method of allocating hard drive space into logical volumes that can be easily resized instead
of partitions.
With LVM, a hard drive or set of hard drives is allocated to one or more physical volumes. A physical
volume cannot span over more than one drive.
The physical volumes are combined into logical volume groups, with the exception of the /boot/
partition. The /boot/ partition cannot be on a logical volume group because the boot loader cannot
read it. If the root (/) partition is on a logical volume, create a separate /boot/ partition which is not a
part of a volume group.
Since a physical volume cannot span over multiple drives, to span over more than one drive, create
one or more physical volumes per drive.
Figure 7.1. Logical Volume Group
The logical volume group is divided into logical volumes, which are assigned mount points, such as /
home and / m and file system types, such as ext2 or ext3. When "partitions" reach their full capacity,
free space from the logical volume group can be added to the logical volume to increase the size of
the partition. When a new hard drive is added to the system, it can be added to the logical volume
group, and partitions that are logical volumes can be expanded.
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