Logical Volume Manager (LVM) - adds an extra layer between the physical disks and the file system, which allows you to resize your storage on the fly, use multiple disks, instead of one, etc.

Concepts:

Physical Volume:

  • Physical Volume represents the actual disk / block device.

Volume Group:

  • Volume Groups combines the collection of Logical Volumes and Physical Volumes into one administrative unit.

Logical Volume:

  • A Logical Volume is the conceptual equivalent of a disk partition in a non-LVM system.

File Systems:

  • File systems are built on top of logical volumes.

What we are doing today:

We have a disk installed on our server which is 150GB that is located on /dev/vdb, which we will manage via LVM and will be mounted under /mnt

Dependencies:

Update and Install LVM:

$ apt update && apt upgrade -y
$ apt install lvm2 -y
$ systemctl enable lvm2-lvmetad
$ systemctl start lvm2-lvmetad

Create the Logical Volume:

Initialize the Physical Volume to be managed by LVM, then create the Volume Group, then go ahead to create the Logical Volume:

$ pvcreate /dev/vdb
$ vgcreate vg1 /dev/vdb
$ lvcreate -l 100%FREE -n vol1 vg1

Build the Linux Filesystem with ext4 and mount the volume to the /mnt partition:

$ mkfs.ext4 /dev/vg1/vol1
$ mount /dev/vg1/vol1 /mnt
$ echo '/dev/mapper/vg1-vol1 /mnt ext4 defaults,nofail 0 0' >> /etc/fstab

Other useful commands:

To list Physical Volume Info:

$ pvs
PV         VG   Fmt  Attr PSize   PFree
/dev/vdb   vg1  lvm2 a--  139.70g    0

To list Volume Group Info:

$ vgs
VG   #PV #LV #SN Attr   VSize   VFree
vg1    1   1   0 wz--n- 139.70g    0

And viewing the logical volume size from the volume group:

$ vgs -o +lv_size,lv_name
VG   #PV #LV #SN Attr   VSize   VFree LSize   LV
vg1    1   1   0 wz--n- 139.70g    0  139.70g vol1

Information about Logical Volumes:

$ lvs
LV   VG   Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
vol1 vg1  -wi-ao---- 139.70g

Resources: