KVM – Resize guest LVM disk
Table of Contents
A practical procedure to grow a KVM guest disk backed by LVM, without downtime on the host.
On the KVM host #
Resize the guest volume #
# LVM-backed guest
lvextend -L +50G /dev/vg_kvm/ubuntu
# QCOW2-backed guest
qemu-img resize ubuntu.qcow2 +50G
Refresh the storage pool #
virsh pool-refresh vg_kvm
Inside the KVM guest #
Check the current disk layout #
fdisk -l
Edit the partition table #
Delete the LVM and Extended partitions, then recreate a single LVM partition spanning the full disk:
fdisk /dev/vda
# d → delete partition 5 (LVM)
# d → delete partition 2 (Extended)
# n → new partition (primary, start at 501760, accept default end)
# t → change type to 8e (Linux LVM)
# w → write and exit
Reboot #
reboot
Resize the LVM stack #
# Resize the physical volume to use the new partition size
pvresize /dev/vda2
# Extend the logical volume
lvextend -L +30G /dev/ubuntu/root
# Grow the filesystem online (ext4)
resize2fs /dev/ubuntu/root
Verify #
df -h
The filesystem is now expanded and online — no downtime required on the host.