How to Expand Linux Disk Space Using fdisk and LVM: Step‑by‑Step Guide

Linux Disk Expansion

After adding a new disk in the console, restart the system and follow the steps below.

Add Partition

Use fdisk /dev/sda to create a new primary partition (e.g., /dev/sda4) of the desired size.

# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): n
Partition type:
   p   primary (3 primary, 0 extended, 1 free)
   e   extended
Select (default e): p
Selected partition 4
First sector (41943040-83886079, default 41943040):
Using default value 41943040
Last sector, +sectors or +size{K,M,G} (41943040-83886079, default 83886079):
Using default value 83886079
Partition 4 of type Linux and of size 20 GiB is set

Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
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 you run partprobe(8) or kpartx(8)
Syncing disks.

View New Partition Types

# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000a9a6f

   Device Boot      Start        End    Blocks   Id  System
/dev/sda1          2048       6143      2048   83  Linux
/dev/sda2 *        6144    2103295   1048576   83  Linux
/dev/sda3       2103296   41943039  19919872   8e  Linux LVM
/dev/sda4       41943040   83886079  20971520   83  Linux

Change Partition Type

Set the partition type to match LVM (type 8e) using fdisk /dev/sda and the t command.

# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): t
Partition number (1-4, default 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!
Calling ioctl() to re-read partition table.
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 you run partprobe(8) or kpartx(8)
Syncing disks.

Verify Modified Partition Type

# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000a9a6f

   Device Boot      Start        End    Blocks   Id  System
/dev/sda1          2048       6143      2048   83  Linux
/dev/sda2 *        6144    2103295   1048576   83  Linux
/dev/sda3       2103296   41943039  19919872   8e  Linux LVM
/dev/sda4       41943040   83886079  20971520   8e  Linux LVM

Disk Expansion

After reboot, extend the logical volume.

Check Volume Group

# lvs
  LV   VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root centos -wi-ao---- <18.00g
  swap centos -wi-ao----   1.00g

# vgdisplay
  --- Volume group ---
  VG Name               centos
  Format                lvm2
  Metadata Areas         1
  VG Access             read/write
  VG Status             resizable
  Cur LV                2
  Cur PV                1
  VG Size               <19.00 GiB
  PE Size               4.00 MiB
  Total PE              4863
  Alloc PE / Size       4863 / <19.00 GiB
  Free  PE / Size       0 / 0

Create Physical Volume

Create a physical volume on the new partition.

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

If the device is not found, run partprobe first to make the kernel aware of the new partition table.

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

Extend Volume Group

# vgextend centos /dev/sda4
Volume group "centos" successfully extended

# vgdisplay
  --- Volume group ---
  VG Name               centos
  Metadata Areas         2
  VG Status             resizable
  Cur LV                2
  Cur PV                2
  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 (4607 extents) to <36.50 GiB (9343 extents).
Logical volume centos/root successfully resized.

Resize Filesystem

For XFS filesystems, run:

# xfs_growfs /dev/mapper/centos-root
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=1179392 blks
... (output truncated) ...
data blocks changed from 4717568 to 9567232

If the filesystem is ext4, use resize2fs instead.

Expansion complete.