How to Expand Linux Disk Space with LVM: Step‑by‑Step Guide

Linux Disk Expansion

After attaching a new disk in the console, restart the system and begin partitioning.

Add Partition

# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Command (m for help): n
Partition type: p (primary)
First sector: 41943040
Last sector: 83886079
Created partition 4 of type Linux, size 20 GiB.
Command (m for help): w
The partition table has been altered!
WARNING: Re‑reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at the next reboot or after running partprobe(8) or kpartx(8).

Verify New Partition Types

# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes, 83886080 sectors
... 
/dev/sda4        41943040    83886079    20971520   83  Linux

Change Partition Type to LVM

Because /dev/sdb3 has ID 8e (Linux LVM), change /dev/sda4 to the same ID.

# fdisk /dev/sda
Command (m for help): t
Partition number (1-4, default 4): 4
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): w
The partition table has been altered!
WARNING: Re‑reading the partition table failed with error 16: Device or resource busy.

Verify Modified Partition Types

# fdisk -l
... 
/dev/sda4        41943040    83886079    20971520   8e  Linux LVM

Disk Expansion

After reboot, extend the volume group and logical volume.

Check Volume Group

# lvs
LV   VG   Attr       LSize
root centos -wi-ao---- <18.00g
swap centos -wi-ao----   1.00g
# vgdisplay
VG Name               centos
VG Size               <19.00 GiB
...

Extend Logical Volume

Create Physical Volume

# pvcreate /dev/sda4
Physical volume "/dev/sda4" successfully created.

If you see "Device /dev/sda4 not found", run partprobe first.

# partprobe
# pvcreate /dev/sda4
Physical volume "/dev/sda4" successfully created.

Extend Volume Group

# vgextend centos /dev/sda4
Volume group "centos" successfully extended
# vgdisplay
VG Name               centos
VG Size               38.99 GiB
Free PE / Size       5119 / <20.00 GiB

Extend Logical Volume

# lvextend -l +100%FREE /dev/centos/root /dev/sda4
Size of logical volume centos/root changed from <18.00 GiB to <36.50 GiB.
Logical volume centos/root successfully resized.

Resize Filesystem

Check Filesystem Type

# df -Th
Filesystem              Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs        37G   14G   24G  37% /

Resize Filesystem

# xfs_growfs /dev/mapper/centos-root
data blocks changed from 4717568 to 9567232

If the filesystem is ext4, use resize2fs instead.

Expansion completed!