The Linux Volume Manager (LVM) maps logical volumes (LVs) onto physical volumes (PVs) through logical and physical extents (LEs and PEs). LVs are created by mapping LEs to PEs so that logical block references are translated to physical blocks. These mappings can be configured to meet goals for performance, scalability, and availability.

1. Linux Volume Manager

2. shows how the logical volumes are
mapped onto physical volumes.
Each PV consists of a number of
fixed-size physical extents (PEs);
similarly, each LV consists of a
number of fixed-size logical extents
(LEs). (LEs and PEs are always the
same size, the default in LVM 2 is 4
MB.) An LV is created by mapping
logical extents to physical extents,
so that references to logical block
numbers are resolved to physical
block numbers. These mappings
can be constructed to achieve
particular performance, scalability,
or availability goals.