Logical Volume Manager configurations

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Basic LVM configuration.

Create an LVM logical volume on three disks

  1. Label disks as LVM physical volumes
  2. Create a volume group consisting of LVM physical volumes created in step 1.
  3. Create a logical volume from the volume group created in step 2.
  4. Create a file system on the logical volume created in step 3.
  5. Mount the logical volume.

Label disks as LVM physical volumes

This command destroys any data on /dev/sda1, /dev/sdb1, and /dev/sdc1.

pvcreate /dev/sda1 /dev/sdb1 /dev/sdc1

Create volume group

vgcreate new_vol_group /dev/sda1 /dev/sdb1 /dev/sdc1

You can display volume groups with vgs command.

Create logical volume

lvcreate -L 2G -n new_logical_volume new_vol_group

Create file system

In this case I’m using ext4.

mkfs.ext4 /dev/new_vol_group/new_logical_volume

Mount logical volume

mount /dev/new_vol_group/new_logical_volume /mnt

You can display file system disk space usage using df -Hcommand.

Adding new disks to an existing logical volume

Let’s say you bought a new disk and want to add it to the logical volume previously created. The steps are:

  1. Attach the new disk to the system.
  2. Label the disk attached in step 1 as LVM physical volume.
  3. Extend the volume group.
  4. Extend the logical volume.
  5. Extend the filesystem.

I’m going to skip step 1 since this is dependant on your system.

Label new disk as LVM physical volume

pvcreate /dev/sdd1

Extend the volume group

First you should identify your volume group with the vgs command. I’m going to use the volume group new_vol_group created in the first part of this post.

vgextend new_vol_group /dev/sdd1

Extend the logical volume

First you should identify your logical volume. I’m going to use the logical volume new_logical_volume created in the first part of this post

lvextend -l +100%FREE /dev/new_vol_group/new_logical_volume

Note: I think there is a method to extend the logical volume and the filesystem with the same command. However, I’m going to do it in two steps because it is what I’m used to.

Extend the filesystem

First confirm the filesystem you are using. In my case is ext4.

resize2fs /dev/new_vol_group/new_logical_volume

Now you should see the size of your extended partition df -H.

References