Installation guide

Table Of Contents

previously been disallowed.

2.4. Resizing a Physical Volume

If you need to change the size of an underlying block device for any reason, use the pvresize

command to update LVM with the new size. You can execute this command while LVM is using

the physical volume.

2.5. Removing Physical Volumes

If a device is no longer required for use by LVM, you can remove the LVM label with the pvre-

move command. Executing the pvremove command zeroes the LVM metadata on an empty phys-

ical volume.

If the physical volume you want to remove is currently part of a volume group, you must remove

it from the volume group with the vgreduce command, as described in Section 3.5, “Removing

Physical Volumes from a Volume Group”.

# pvremove /dev/ram15

Labels on physical volume "/dev/ram15" successfully wiped

3. Volume Group Administration

This section describes the commands that perform the various aspects of volume group admin-

istration.

3.1. Creating Volume Groups

To create a volume group from one or more physical volumes, use the vgcreate command. The

vgcreate command creates a new volume group by name and adds at least one physical

volume to it.

The following command creates a volume group named vg1 that contains physical volumes /

dev/sdd1 and /dev/sde1.

vgcreate vg1 /dev/sdd1 /dev/sde1

When physical volumes are used to create a volume group, its disk space is divided into 4MB

extents, by default. This extent is the minimum amount by which the logical volume may be in-

creased or decreased in size. Large numbers of extents will have no impact on I/O performance

of the logical volume.

You can specify the extent size with the vgcreate command if the default is not suitable with the

-s argument. You can put limits on the number of physical or logical volumes the volume group

can have by using the -p and -l arguments of the vgcreate command.

By default, a volume group allocates physical extents according to common-sense rules such as

not placing parallel stripes on the same physical volume. This is the normal allocation policy.

You can use the --alloc argument of the vgcreate command to specify an allocation policy of

contiguous, anywhere, or cling.

2.4. Resizing a Physical Volume