20.3 About Logical Volume Manager

You can use Logical Volume Manager (LVM) to manage multiple physical volumes and configure mirroring and striping of logical volumes to provide data redundancy and increase I/O performance. In LVM, you first create volume groups from physical volumes, which are storage devices such as disk array LUNs, software or hardware RAID devices, hard drives, and disk partitions. You can then create logical volumes in a volume group. A logical volume functions as a partition that in its implementation might be spread over multiple physical disks.

You can create file systems on logical volumes and mount the logical volume devices in the same way as you would a physical device. If a file system on a logical volume becomes full with data, you can increase the capacity of the volume by using free space in the volume group so that you can then grow the file system (provided that the file system has that capability). If necessary, you can add physical storage devices to a volume group to increase its capacity.

LVM is non-disruptive and transparent to users. You can increase the size of logical volumes and change their layout dynamically without needing to schedule system down time to reconfigure physical storage.

LVM uses the device mapper (DM) that provides an abstraction layer that allows the creation of logical devices above physical devices and provides the foundation for software RAID, encryption, and other storage features.