VERITAS Volume Manager 3.1 Migration Guide

VxVM and LVM
VxVM and LVM—Conceptual Comparison
Chapter 1 19
An LVM logical volume and a VxVM volume are conceptually the same. Both are
virtual disk devices that appear to applications, databases, and file systems like
physical disk devices, but do not have the physical limitations of physical disk
devices. Due to its virtual nature, a volume (LVM or VxVM) is not restricted to a
particular disk or a specific area of a disk.
An LVM volume is composed of fixed length extents. LVM volumes can be
mirrored or striped.
VxVM volumes consist of one or more plexes/mirrors holding a copy of the data in
the volume which in turn are made up of subdisks with arbitrary length. The
configuration of a volume can be changed by using the VxVM user interfaces. See
the VERITAS Volume Manager 3.1 Administrator’s Guide for more information.
VxVM volumes can be one of four types: mirrored, RAID-5, striped, or
concatenated.
Volume Group Disk Group
LVM volume groups are conceptually similar to VxVM disk groups.
An LVM volume group is the collective identity of a set of physical volumes, which
provide disk storage for the logical volumes.
A VxVM disk group is a collection of VxVM disks that share a common
configuration. A configuration is a set of records with detailed information about
related VxVM objects, their attributes, and their associations.
In addition, both LVM and VxVM have the following characteristics:
Volumes can be mapped to multiple VxVM disks or LVM physical volumes.
VxVM disks must reside in only one disk group, and LVM physical volumes must
reside in one volume group.
Physical Extent Subdisk
Table 1-1A Conceptual comparison of LVM and VxVM
LVM Term VxVM Term