Novell LINUX ENTERPRISE SERVER 11 - DEPLOYMENT, Руководство по развертыванию

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can be created as needed. The operating system accesses these LVs instead of the
physical partitions. Volume groups can span more than only one disk so that several
disks or parts of them may constitute one single VG. This way, LVM provides a kind
of abstraction from the physical disk space that allows its segmentation to be changed
in a much easier and safer way than physical repartitioning does. Background information
regarding physical partitioning can be found in
Section 15.1.1, “Partition Types”
(page 229) and Section 15.1, “Using the YaST Partitioner” (page 227).
Figure 15.2 Physical Partitioning versus LVM
PART PART PART PART PART
DISK
PART PART PART
MP MP MP MP MP MP MP
DISK 1 DISK 2
VG 1 VG 2
LV 1 LV 2 LV 3 LV 4
Figure 15.2, “Physical Partitioning versus LVM” (page 236) compares physical parti-
tioning (left) with LVM segmentation (right). On the left side, one single disk has been
divided into three physical partitions (PART), each with a mount point (MP) assigned
so that the operating system can access them. On the right side, two disks have been
divided into two and three physical partitions each. Two LVM volume groups (VG 1
and VG 2) have been defined. VG 1 contains two partitions from DISK 1 and one from
DISK 2. VG 2 contains the remaining two partitions from DISK 2. In LVM, the physical
disk partitions that are incorporated in a volume group are called physical volumes
(PVs). Within the volume groups, four LVs (LV 1 through LV 4) have been defined,
which can be used by the operating system via the associated mount points. The border
between different LVs need not be aligned with any partition border. See the border
between LV 1 and LV 2 in this example.
LVM features:
• Several hard disks or partitions can be combined in a large logical volume.
• Provided the configuration is suitable, an LV (such as /usr
) can be enlarged when
the free space is exhausted.
236 Deployment Guide