Create and remove physical volumes, assign physical volumes to volume groups, create and delete logical volumes Create and remove physical volumes

Creating a physical volume in LVM is the first step in the LVM setup. Its the part where you actually tell Red Hat Enterprise Linux that you want a disk to be used for LVM.

pvcreate is the command used to add the physical volumes, or physical partitions.

~] pvcreate /dev/sdb
~] Physical volume “/dev/sdb” successfully created

pvremove is used to disassociate the volume from LVM.

~] pvremove /dev/sdb
~] Labels on physical volume “/dev/sdb” successfully wiped

Assign physical volumes to volume groups

Once that physical volume has been created we can add it to a volume group with the vgcreate or vgextend (if the volume group has already been created).

If the volume group does not exist, you can create it and add physical volumes in one shot:

~] vgextend MyVolGroup /dev/sdc
No physical volume label read from /dev/sdc
Physical volume “/dev/sdc” successfully created
Volume group “MyVolGroup” successfully extended

To assign a new physical volume to an existing volume group we use vgextend:

~] vgextend MyVolGroup /dev/sdc
Volume group “MyVolGroup” successfully extended

Similarly if we want to remove /dev/sdc from that group we would run ”vgreduce”:

~] vgreduce MyVolGroup /dev/sdc
Removed “/dev/sdc” from volume group “MyVolGroup”

Create and delete logical volumes

Logical Volumes have similar commands to create and delete as Volume Groups and Physical Volumes.

To create a new logical volume:

~] lvcreate -L 100M MyVolGroup
Logical volume “lvol0” created

To display the volume after for confirmation:

~] lvdisplay MyVolGroup
— Logical volume —
LV Name /dev/MyVolGroup/lvol0
VG Name MyVolGroup
LV UUID zwLMev-i63w-7Jpk-XuqZ-VGl7-89Ov-WpoewP
LV Write Access read/write
LV Status available
# open 0
LV Size 100.00 MiB
Current LE 25
Segments 1
Allocation inherit
Read ahead sectors auto
– currently set to 256
Block device 253:2

To delete the logical volume you would use the LV Name listed in the results of lvdisplay:

:::bash ~] lvremove /dev/MyVolGroup/lvol0 Do you really want to remove active logical volume lvol0? [y/n]: y Logical volume “lvol0” successfully removed