LVM 101: A Beginner's Guide to Logical Volume Management on Ubuntu

Last Update: Apr 27, 2025

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Ever wished your Linux storage was more flexible and less “stuck in the mud”? That’s where LVM comes in. Logical Volume Management gives you the power to manage storage like a pro—resize volumes on the fly, combine multiple disks, and move things around without breaking a sweat.

Let’s get our hands dirty and explore the basics—with a real example using loop devices so you don’t need extra hardware.

🧱 LVM Building Blocks: Lego for Your Linux Storage

First, let’s break down what LVM is made of. Think of these as the building blocks of your storage system:

• Physical Volumes (PVs): These are your actual drives or partitions—like /dev/sda1, /dev/sdb, or even virtual loop devices.
• Volume Groups (VGs): Combine your physical volumes into one big storage pool. It’s like mixing Legos from multiple sets into one big bin.
• Logical Volumes (LVs): This is where the magic happens. You carve out usable chunks from your volume group. These are what you format and mount as filesystems.

Here’s a simple map of how they connect:

Neat, right? Now let’s make it real.

🛠️ Installing LVM on Ubuntu

LVM is often already installed, but if it’s not, just run:

sudo apt update
sudo apt install lvm2

Verify it with:

sudo lvm version

If you see version info—boom, you’re good to go.

🧪 Hands-On Demo: Expanding a Filesystem with Loop Devices

Let’s simulate a scenario where you want to add more space to your server. We’ll use loop devices (virtual disks) so you don’t risk real data.

🔁 Step 1: Create Fake Disks

sudo fallocate -l 500M /tmp/disk1.img
sudo fallocate -l 500M /tmp/disk2.img
sudo losetup /dev/loop0 /tmp/disk1.img
sudo losetup /dev/loop1 /tmp/disk2.img

Now you’ve got two fake 500MB disks. Sneaky, huh?

🧱 Step 2: Set Up Physical Volumes

sudo pvcreate /dev/loop0
sudo pvcreate /dev/loop1
sudo pvs

You should see both loop devices ready for action.

🧰 Step 3: Create Your Volume Group

Next, let’s create a volume group. This is where you’ll combine your physical volumes into one big happy family.

sudo vgcreate vg_demo /dev/loop0
sudo vgs

We’ll add the second disk later.

📦 Step 4: Create a Logical Volume

sudo lvcreate -L 400M -n lv_data vg_demo

Check it out with:

sudo lvs

You should see your new logical volume. It’s like a mini partition inside your volume group.

Or get the deep details:

sudo lvdisplay /dev/vg_demo/lv_data

🧹 Step 5: Format the Volume

sudo mkfs.ext4 /dev/vg_demo/lv_data

📂 Step 6: Mount It

sudo mkdir /mnt/lvm_data
sudo mount /dev/vg_demo/lv_data /mnt/lvm_data
df -h /mnt/lvm_data

Now you can use it like any other filesystem. Check the space with df -h.

You’ll see about 400MB of usable space.

➕ Step 7: Add Another Disk

sudo vgextend vg_demo /dev/loop1
sudo vgs

Now you’ve added the second disk to your volume group. This is where LVM shines—no downtime, no fuss.

Your volume group just got bigger. Pretty awesome, right?

🧱 Step 8: Expand the Logical Volume

sudo lvextend -L +500M /dev/vg_demo/lv_data
sudo lvs

Now it’s bigger, but we’re not done yet.

🔧 Step 9: Grow the Filesystem

sudo resize2fs /dev/vg_demo/lv_data

Now you can actually use the extra space!

🧪 Step 10: Verify It

df -h /mnt/lvm_data

You should now see the full ~900MB available.

🧹 Clean-Up (Optional)

Don’t want to keep the setup? Tear it down safely:

sudo umount /mnt/lvm_data
sudo lvremove /dev/vg_demo/lv_data
sudo vgremove vg_demo
sudo pvremove /dev/loop0
sudo pvremove /dev/loop1
sudo losetup -d /dev/loop0
sudo losetup -d /dev/loop1
sudo rm /tmp/disk1.img /tmp/disk2.img
sudo rmdir /mnt/lvm_data

🧭 Wrapping Up

Here’s what we learned:

• LVM makes managing storage super flexible.
• You can add space, resize volumes, and do it all live—no reboot needed.
• Loop devices are awesome for safe, hands-on learning.

Want to go further? Check out LVM features like snapshots, striping, and mirroring. You’ve got the basics down—keep experimenting!

🙋‍♂️ Got Questions?

Q: Can I use this with real disks?
Absolutely. Just swap /dev/loopX with something like /dev/sdb. But be careful—real data is on the line.

Q: Why LVM?
Because resizing and reorganizing your disk space without rebooting is kind of a superpower.

Q: Do I have to reboot after changes?
Nope. That’s one of the big perks of LVM.

Until next time—Happy hacking! 💻🔥

Published: Apr 22, 2025 by Jeremy Morgan. Contact me before republishing this content.