Expand Your Root Partition with LVM in Ubuntu (No Reformat Needed)

Photo by Gabriel Heinzer on Unsplash

After setting up Ubuntu on my 1TB NVMe SSD, I noticed something strange: only 100GB of space was being used — even though the disk was almost ten times larger. The rest? Unused but technically allocated under LVM.

If you’re in a similar situation, here’s how I recovered ~850GB of unused space without reformatting or reinstalling anything.

🖥️ My Setup

Here’s what lsblk looked like:

nvme0n1
├─nvme0n1p1  /boot/efi
├─nvme0n1p2  /boot
└─nvme0n1p3  
   └─ubuntu--vg-ubuntu--lv  /

My root filesystem (/) was sitting on an LVM logical volume (ubuntu-lv), and only 100GB had been allocated — even though /dev/nvme0n1p3 was nearly 950GB.

🔍 Step 1: Verifying Free Space

To see how much space was left in the LVM volume group:

sudo vgs

Output:

VG         #PV #LV #SN Attr   VSize    VFree   
ubuntu-vg    1   1   0 wz--n- <950.82g <850.82g

Over 850GB of free space inside the ubuntu-vg volume group! This meant I could easily expand my current root volume without adding new disks or partitions.

⚙️ Step 2: Extending the Root Filesystem

Instead of creating a new volume, I decided to extend my root filesystem directly. Here’s how:

1. Extend the Logical Volume

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

This tells LVM to use all remaining free space in the volume group for the ubuntu-lv logical volume.

2. Resize the Filesystem

Since my root filesystem is formatted as ext4, I ran:

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

For xfs filesystems, you'd use sudo xfs_growfs /.

🧪 Step 3: Verifying the Results

To confirm that the space was successfully added:

df -h /

And there it was — my root partition had grown from 100GB to nearly 950GB, instantly.

✅ Final Thoughts

LVM is incredibly flexible. Even if you initially allocate a small portion of your disk, you can expand it later without any downtime or reinstallations.

If you’re using LVM and haven’t tapped into all your disk space — check your volume group. There might be hundreds of gigabytes waiting to be used.

💬 Have you done something similar or faced challenges with LVM? Drop a comment or share this post with someone who’s stuck with “mysteriously full” disks.