www.dell.com/powersolutions POWER SOLUTIONS
111
STORAGE ENVIRONMENT
Implementing Logical Volumes
on Linux-based Dell PowerEdge Servers
Sistina
Logical Volume Manager (LVM) software provides an abstraction layer that
allows administrators to work with logical volumes, helping to simplify storage
management. This article describes LVM and presents scenarios for using LVM to
resize storage volumes on Dell
™
PowerEdge
™
and PowerVault
™
systems running
the Red Hat
Linux
operating system.
S
ystem administrators who manage disk storage in net-
work environments face several challenges: ensuring
that data-intensive applications get the data they need
quickly, providing and organizing additional storage,
preserving data integrity, and backing up data regularly.
Scalable storage management software that enables admin-
istrators to reconfigure storage allocations dynamically in
response to changing enterprise needs can help meet
these challenges. One such open source product is the
Sistina
®
Logical Volume Manager (LVM), which is embed-
ded in the Linux
®
kernel. LVM combines physical disk
drives into easily manageable logical volumes and allows
online storage administration through tasks that are trans-
parent to the user and the application.
This article discusses the basic architecture and con-
figuration of LVM running under the Red Hat
®
Linux oper-
ating system. It also explains the steps for using LVM to
manage storage in Dell
™
PowerEdge
™
servers and Dell
PowerVault
™
systems.
Understanding LVM architecture
LVM comprises five basic structures: volume group (VG),
logical volume (LV), logical extent (LE), physical extent
(PE), and physical volume
(PV). A physical volume
is typically a hard disk or
a partition—for example,
a SCSI disk or a RAID
abstraction of a hard disk.
Each physical volume
comprises chunks of data,
called physical extents. All
physical extents within a
volume group are the
same size. In Figure 1,
the volume group, called
Vol_Grp00, is at the top
level of abstraction. This
group is obtained by
BY TESFAMARIAM MICHAEL AND JOSHUA GILES
LVM combines physical
disk drives into easily
manageable logical
volumes and allows
online storage adminis-
tration through tasks that
are transparent to the
user and the application.
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