What is LVM?

Reza Mohammadi

3 min readFeb 24, 2024

What is LVM? and How to use LVM?

In this article, we are going through the LVM, its features, and its configuration.

Logical Volume Manager (LVM)

LVM is a tool to partition your file systems and manage them. You can have one partition on several disks.
LVM is a solution for better managing servers with several Physical Hard Disks.
In LVM, we have three objects: 1. Physical Volume (PV) 2. Group Volume (GV) 3. Logical Volume (LV)
We see LV as a disk and mount it. Also, we can create GV from PVs and make different groups for different data.
LVM features are: 1. Shared Partition 2. Extend LV (whenever needed).

Linux modules have .ko extension and compile with C language.
Linux modules path: /lib/modules/kernel-version

Install LVM:

$ apt install lvm2

Physical Volume (PV) Administration

Initializing Physical Volume:

# Create PV on one disk
$ pvcreate /dev/sdb

# Even you can create PV on a created partition
$ pvcreate /dev/sdc1 /dev/sdd1

Display Physical Volumes:

$ pvs
or
$ pvdisplay

Scanning current system for physical volumes:

$ pvscan

Removing a physical volume:

$ pvremove /dev/sdc1

Volume Group (VG) Administration

Creating Volume Groups:

$ vgcreate vg1 /dev/sdc1 /dev/sdd1

Add/Remove a new PV to an existing VG:

# Add
$ vgextend vg1 /dev/sde

# Remove
$ vgreduce vg1 /dev/sdd1

Displaying Volume Groups:

$ vgs
or
$ vgdisplay

Scan existing Volume Groups:

$ vgscan

Removing a Volume Group:

$ vgremove vg1

Logical Volume (LV) Administration

Creating a Logical Volume:

$ lvcreate --name lv1 -L 10G vg1

Extend/Reduce a Logical Volume:

# Extend
$ lvextend -L +1G /dev/vg1/lv1
# To take effect, if it is mounted, unmount(umount) it and then:
$ fsck -f /dev/vg1/lv1
$ resize2fs /dev/vg1/lv1
# Now you can mount it again!

# Reduce
$ lvreduce -L -1G /dev/vg1/lv1
# To take effect, if it is mounted, unmount(umount) it and then:
$ fsck -f /dev/vg1/lv1
$ resize2fs /dev/vg1/lv1
# Now you can mount it again!

⚠️ Before unmounting, fsck, and resizing, backup your data, there is the possibility of losing your data!

Display/Remove a Logical Volume:

# Display
$ lvs 
or 
$ lvdisplay

# Scan
$ lvscan# Remove
$ lvremove /dev/vg1/lv1

LVM Snapshots

Snapshot Volume is a volume that when you use it, freezes & backups LVM until that moment.
You can give your desired size of backup to your snapshot.

Create Snapshot

# Creating snapshot "lvsnap1" with size 100M from lv1:
$ lvcreate --snapshot --size 100M --name lvsnap1 /dev/vg1/lv1

# The newly created snapshots can be mounted & used:
$ mkdire /backup
$ mount /dev/vg1/lvsnap1 /backup# Restore snapshot on the LVM again:
$ umount /dev/vg1/lvsnap1
$ mount /dev/vg1/lvsnap1 /mnt# Delete; first you should umount it then:
$ lvremove /dev/vg1/lvsnap1