LVM conceptions
Author : weLees
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LVM (Logical Volume Management) is one of storage pool technology on the Linux platform. It abstracts the physical devices in the system into virtual devices for users. This technology provides a rich set of features to match their various needs.
This article introduces the concepts in LVM:
PE
The Physical Extent is the basic unit of storage in LVM, and its value can be specified by the user, usually 4MB. LVM divides physical devices into a combination of several PEs. This concept is similar to a cluster of file systems.
LE
Logical Extent, the basic unit for logical volumes. In the same VG, the values of LE and PE are the same.
PV
Physical Volume is a physical device used to store data, usually a disk partition, but it may be the entire disk.
LV
Logical Volume, the virtual volume device that the LVM system virtualizes for users to use. Depending on the configuration, users can get different features such as maximum performance, maximum security, snapshots, and caching.
VG
Volume Group, is an independent working LVM unit, is a collection of LV and PV. It consists of one or more PVs, and then the PV is configured to provide the user with an abstract LV.
The architecture of LVM: VG, LV & PV