Introduction

Expanding an Ubuntu LVM partition after increasing a virtual disk is a common maintenance task for Linux administrators. However, many users discover that the root filesystem still reports its original size even after the virtual disk has been expanded.

You expand the virtual disk in VMware, Proxmox, Hyper-V, KVM, or your VPS provider‘s control panel, reboot the VM, run df -h, and… nothing changed.

This usually happens because Ubuntu is installed using LVM (Logical Volume Manager). Increasing the virtual disk only makes additional space available at the disk level. You still need to expand the partition, resize the LVM physical volume, extend the logical volume, and finally grow the filesystem.

If you need to expand an Ubuntu LVM partition after increasing a virtual disk, you may find that the root filesystem still reports its original size. This happens because the partition, LVM physical volume, logical volume, and filesystem must each be expanded separately.

This guide walks through the complete process we recently used while helping a customer expand their Ubuntu server.

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How to Expand an Ubuntu LVM Partition After a Disk Resize

Symptoms

You increase the VM’s disk from 50 GB to 100 GB, but the server still reports approximately 50 GB available.

Typical output looks something like this:

$ df -h

Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv   49G   41G  5.8G  88% /
Code language: PHP (php)

Meanwhile, lsblk may show something similar:

$ lsblk

NAME                         SIZE TYPE MOUNTPOINT
vda                          100G disk
├─vda1                         1M part
├─vda2                         2G part /boot
└─vda3                        98G part
  └─ubuntu--vg-ubuntu--lv     49G lvm  /

Notice the important detail:

• The virtual disk is now 100 GB.
• The LVM logical volume is still only 49 GB.

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Why This Happens

An Ubuntu LVM installation typically has four layers:

Virtual Disk
      ↓
Partition (vda3)
      ↓
LVM Physical Volume (PV)
      ↓
Volume Group (VG)
      ↓
Logical Volume (LV)
      ↓
Filesystem (ext4 or XFS)

Expanding the virtual disk only changes the top layer.

Each lower layer must be expanded before Linux can actually use the new space.

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Step 1: Verify the Current Layout

Start by checking what you’re working with.

View disks and partitions

lsblk

Check mounted filesystem sizes

df -h

View LVM Physical Volumes

pvs

Example:

PV         VG         Fmt  Attr PSize   PFree
/dev/vda3  ubuntu-vg  lvm2 a--   98.0g     49g

View Volume Groups

vgs

Example:

VG         #PV #LV VSize   VFree
ubuntu-vg    1   1 98.0g   49g
Code language: CSS (css)

View Logical Volumes

lvs

Example:

LV         VG         Attr       LSize
ubuntu-lv  ubuntu-vg  -wi-ao---- 49.0g
Code language: CSS (css)

These commands tell you exactly where the unused space exists.

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Step 2: Expand the Partition

If the partition itself doesn’t already occupy the new disk space, you’ll need to grow it first.

Option 1: Using growpart (recommended)

If installed:

sudo growpart /dev/vda 3

This tells growpart to expand partition 3 on disk /dev/vda.

If the utility isn’t installed:

sudo apt update
sudo apt install cloud-guest-utils

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Option 2: Using parted

If growpart isn’t available:

sudo parted /dev/vda

Inside parted:

print
resizepart 3 100%
quit
Code language: PHP (php)

This safely extends partition 3 to the end of the disk.

Afterward, verify:

lsblk

You should now see the partition occupying the newly expanded disk.

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Step 3: Resize the LVM Physical Volume

Now tell LVM that its underlying partition has grown.

sudo pvresize /dev/vda3

Example output:

Physical volume "/dev/vda3" changed
1 physical volume(s) resized.
Code language: JavaScript (javascript)

Verify:

pvs

You should now see free space available in the Volume Group.

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Step 4: Extend the Logical Volume

Now allocate the newly available space to your root logical volume.

To use all available free space:

sudo lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv

Or, on many Ubuntu systems:

sudo lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv

What this command does:

• lvextend grows the logical volume.
• -l +100%FREE tells LVM to use all remaining free extents in the volume group.

You can also extend by a specific amount, for example:

sudo lvextend -L +20G /dev/ubuntu-vg/ubuntu-lv

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Step 5: Grow the Filesystem

The logical volume is now larger, but the filesystem still needs to be expanded.

First determine the filesystem type:

df -Th

If using ext4

sudo resize2fs /dev/ubuntu-vg/ubuntu-lv

If using XFS

sudo xfs_growfs /

Most Ubuntu server installations use ext4, while XFS is more common on some enterprise distributions.

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Step 6: Verify Everything Worked

Finally, verify the new capacity.

df -h

Example:

Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv   98G   41G   53G  44% /
Code language: PHP (php)

Also verify:

lsblk

pvs

vgs

lvs

Everything should now report the expected sizes.

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Troubleshooting

pvresize says there is no additional space

The partition probably wasn’t expanded successfully.

Check:

lsblk

If the partition size hasn’t changed, revisit Step 2.

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growpart not found

Install it:

sudo apt install cloud-guest-utils

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lvextend reports no free extents

Run:

vgs

If VFree is zero, the physical volume hasn’t been resized yet.

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resize2fs says the filesystem is already the requested size

The logical volume likely wasn’t extended.

Verify:

lvs

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Wrong filesystem command

Using:

resize2fs

on XFS won’t work.

Using:

xfs_growfs

on ext4 won’t work either.

Always verify first:

df -Th

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Lessons Learned

The biggest takeaway is that expanding a virtual disk is only the first step.

With an LVM-based Ubuntu installation, there are multiple layers that each need to know about the additional space:

1. Virtual disk
2. Partition
3. Physical Volume (PV)
4. Volume Group (VG)
5. Logical Volume (LV)
6. Filesystem

If you skip any one of these layers, Linux won’t be able to use the newly allocated storage.

Taking a minute to inspect the layout with lsblk, pvs, vgs, and lvs before making changes can quickly show where the process stopped.

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Final Takeaway

If your Ubuntu root partition is still full after increasing the virtual disk size, don’t assume the resize failed. In most cases, the additional capacity is already available—it just hasn’t been propagated through LVM yet.

The overall workflow is straightforward:

1. Verify the current disk and LVM layout.
2. Expand the partition with growpart or parted.
3. Resize the LVM physical volume with pvresize.
4. Extend the logical volume using lvextend.
5. Grow the filesystem with resize2fs or xfs_growfs.
6. Confirm the results with df -h.

Once you understand how these layers fit together, extending an Ubuntu LVM disk becomes a quick maintenance task instead of a frustrating troubleshooting session.