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Operation Manual

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WARNING
Using LVM is sometimes associated with increased risk such as data loss. Risks
also include application crashes, power failures, and faulty commands. Save
your data before implementing LVM or reconguring volumes. Never work
without a backup.
2.2.1 The Logical Volume Manager
The LVM enables exible distribution of hard disk space over several le systems. It
was developed because sometimes the need to change the segmenting of hard disk space
arises just after the initial partitioning has been done. Because it is difcult to modify
partitions on a running system, LVM provides a virtual pool (volume group, VG for
short) of memory space from which logical volumes (LVs) can be created as needed.
The operating system accesses these LVs instead of the physical partitions. Volume
groups can occupy more than one disk, so that several disks or parts of them may con-
stitute 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 with physical repartitioning. Background information regarding physical partitioning
can be found in Section 2.1.1, “Partition Types” (page 41) and Section 2.1, “Using the
YaST Partitioner” (page 39).
Figure 2.2
Physical Partitioning versus LVM
Figure 2.2, “Physical Partitioning versus LVM” (page 48) compares physical partitioning
(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
48 Reference