🛠 Expanding Root Filesystem on Ubuntu with LVM (Virtual Machine)

📋 Use Case

When a virtual machine runs out of space on the root (/) partition, and the underlying disk has already been expanded via the hypervisor or cloud platform.

This guide applies to systems using:

• Ubuntu Server (e.g., 22.04 LTS)

• LVM-managed disks

• A single-root disk layout (e.g., /dev/mapper/ubuntu--vg-ubuntu--lv)

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🧾 Prerequisites

• A snapshot or backup of the VM (highly recommended)

• Root/sudo access

• Disk already expanded in the hypervisor (e.g., from 72GB to 250GB)

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🪜 Step-by-Step Instructions

1. Check Current Disk Usage

2. List Disks and Partitions

Look for:

• The disk (e.g., xvda)

• The root LVM volume (e.g., /dev/mapper/ubuntu--vg-ubuntu--lv)

• Confirm that a partition (e.g., xvda3) is larger than the mounted root volume

3. Extend the Logical Volume

4. Resize the Filesystem

Assuming you're using ext4:

💡 To confirm the filesystem type:

5. Verify Expansion

You should now see the full size available (e.g., ~146GB instead of 72GB).

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🧼 Optional: Clean Up Old Snapshots & Logs

Free up even more space:

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✅ Outcome

The root filesystem is now successfully extended. The server will run normally with more disk space, avoiding future outages caused by full disks.