Extend a Disk on Ubuntu Server (VMware, LVM, ext4, XFS)

27 February 2025

1. Grow the disk in vCenter

VM > Edit Settings > select the disk and increase its size. Most VMs allow hot-extend; if not, power off first. The VM must have no snapshots.

2. Make Ubuntu see the new size

lsblk -f                    # disks, partitions, filesystems and mount points
sudo fdisk -l /dev/sdX      # real disk size

If the size hasn't changed, rescan the disk (replace sdX):

echo 1 | sudo tee /sys/class/block/sdX/device/rescan

3. Which case are you in?

Case	How to spot it	Go to
Disk with partitions (e.g. `sda3` with LVM)	`lsblk` shows children under the disk	Section 4
Disk without partitions (e.g. `sdb` mounted directly)	`lsblk` shows no children	Section 5

4. Disk with partition + LVM (default Ubuntu install)

sudo growpart /dev/sda 3           # grow partition 3 to use the new space
sudo pvresize /dev/sda3            # tell LVM the PV is bigger
sudo pvs                           # PFree should now show free space
sudo lvextend -r -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv
df -h /

-r resizes the filesystem too. If it fails, resize it by hand as in section 5.

5. Disk without partitions

Check the filesystem with lsblk -f /dev/sdb, then:

sudo resize2fs /dev/sdb     # ext4: takes the device
sudo xfs_growfs /var        # XFS: takes the mount point
df -h /var

Both work online, no need to unmount.

Notes

growpart comes in cloud-guest-utils (sudo apt install cloud-guest-utils).
Don't use pvresize or lvextend on disks without LVM.
If lsblk -f shows an LVM PV directly on a whole disk, skip growpart and start at pvresize /dev/sdX.
On GPT disks, check there's no other partition after the one you want to grow.