Installation guide

512 bytes in size.
Figure 2.1. Physical Volume layout
1.2. Multiple Partitions on a Disk
LVM allows you to create physical volumes out of disk partitions. It is generally recommended
that you create a single partition that covers the whole disk to label as an LVM physical volume
for the following reasons:
• Administrative convenience
It is easier to keep track of the hardware in a system if each real disk only appears once.
This becomes particularly true if a disk fails. In addition, multiple physical volumes on a
single disk may cause a kernel warning about unknown partition types at boot-up.
• Striping performance
LVM can not tell that two physical volumes are on the same physical disk. If you create a
striped logical volume when two physical volumes are on the same physical disk, the stripes
could be on different partitions on the same disk. This would result in a decrease in perform-
ance rather than an increase.
Although it it is not recommended, there may be specific circumstances when you will need to
divide a disk into separate LVM physical volumes. For example, on a system with few disks it
may be necessary to move data around partitions when you are migrating an existing system to
LVM volumes. Additionally, if you have a very large disk and want to have more than one
volume group for administrative purposes then it is necessary to partition the disk. If you do
have a disk with more than one partition and both of those partitions are in the same volume
group, take care to specify which partitions are to be included in a logical volume when creating
1.2. Multiple Partitions on a Disk
7