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Expanding your linux VM Disk: Resize LVM partition without creating a new one

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Below is a friendly, step-by-step guide to resizing a Linux VM’s disk without creating a new partition. We’ll walk through extending the last partition on a disk, resizing a Physical Volume (PV), then resizing the associated Logical Volume (LV) within LVM.

Why Resize This Way?

When you run out of space, you could add a new partition, set up a new PV on it, and then merge it into your Volume Group. That’s often simpler at first glance. However, there are a few reasons to extend an existing partition rather than create a new one:

  • More Straightforward Resizing: Resizing a single partition (and the corresponding PV) is usually more predictable than creating multiple PVs of various sizes. You don’t have to remember which PV belongs to which partition when everything lives on the same extended partition
  • Consistency for Backups & Snapshots: Some backup strategies or snapshot tools prefer (or require) a simpler underlying structure. One partition with a single PV is easier to handle than multiple scattered partitions
  • Less Complexity: Adding more partitions and more PVs can make your system’s storage layout harder to track. It’s cleaner to maintain a single partition; it also looks better ;)

TL;DR (Short Version)

If you only need the commands, here they are:

# 0. Install required dependencies
apt update && apt install -y gdisk parted

# 1. Check Disk Layout
lsblk
gdisk -l /dev/sda

# 2. (Optional) Move GPT structures to the end, if needed
sgdisk -e /dev/sda

# 3. Delete & recreate the last partition
sgdisk -d 3 -n 3:START_SECTOR:0 -t 3:8E00 /dev/sda

# 4. Reload partition table
partprobe -s

# 5. Resize the Physical Volume (PV)
pvresize /dev/sda3

# 6. Resize the Logical Volume (LV)
lvextend -r -l +100%FREE /dev/mapper/<YourVGName-YourLVName>

Step-by-Step Guide

Little note before we start, I assume that we want to extend the sda partition. If you have a different disk, replace sda with your disk name (e.g., sdb, sdc, etc.).

1. Identify the Target Disk and Partition

1.1 Find Your Disk Device Path

First, identify the disk you want to resize. You can use lsblk to list all block devices and their partitions. Example output:

 NAME                             MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
 sda                                8:0    0   70G  0 disk
 ├─sda1                             8:1    0  512M  0 part /boot/efi
 ├─sda2                             8:2    0  488M  0 part /boot
 └─sda3                             8:3    0   69G  0 part
   ├─myvg-root                    254:0    0   68G  0 lvm  /
   └─myvg-swap                    254:1    0    1G  0 lvm  [SWAP]
 sr0                               11:0    1 1024M  0 rom

1.2 Verify the Target Partition Is the Last One

Look for the Start and End sectors to confirm your partition is at the end of the disk.

gdisk -l /dev/sda

Example output:

Number  Start (sector)    End (sector)  Size       Code  Name
   1         2048         1050623       512.0 MiB  EF00
   2      1050624         2050047       488.0 MiB  8300
   3      2050048       146800606       69.0 GiB   8E00

1.3 Take note of Sector and Code

Make a note of the Start sector and Code for the last partition. You’ll need these values for step 2.2. The Code is the partition type. In this example, 8E00 is the code for Linux LVM.

2. Resize the Partition

2.1 Move GPT Structures (Optional)

This step makes sure your GPT metadata is at the very end of the disk so you can fully use any additional space:

sgdisk -e /dev/sda

2.2 Delete and Recreate the Last Partition

Use the values you got from step 1.2 and enter them here. In my case this was 2050048and 8E00. Critical: Keep the same start sector as before and extend (:0) to the end. This won’t erase data if you do not change the start sector.

sgdisk -d 3 -n 3:2050048:0 -t 3:8E00 /dev/sda
  • -d 3: Delete partition 3
  • -n 3:2050048:0: Create a new partition 3 starting at sector 2050048 and extending to the end of the disk
  • -t 3:8E00: Set the partition type to Linux LVM

2.3 Reload the Partition Table

The system won’t recognize the new partition size until you reload the partition table:

partprobe -s

3. Resize the Physical Volume (PV) and Logical Volume (LV)

3.1 Resize the Physical Volume

You’ll see something like /dev/sda3 mapped to your Volume Group (VG).

pvs

Identify which LV you want to grow (e.g., root, data, etc.).

lvs

3.2 Resize the Physical Volume

pvresize /dev/sda3

Your PV now recognizes the newly available space on the extended partition.

3.3 Resize the Logical Volume

Change myvg-root with the LVM you actually want to extend (see step 1.1)

sudo lvextend -r -l +100%FREE /dev/mapper/myvg-root
  • -r: Resize the filesystem after resizing the LV
  • -l +100%FREE: Use all available space
  • /dev/mapper/<YourVGName-YourLVName>: Replace with your VG and LV names

4. Verify the Resized Disk and Filesystem

Confirm the new size is reflected in your PV, LV, and filesystem.

pvs
lvs
df -h

Optional reboot: Not needed for the system itself to recognize the new size, but a reboot may help if some services or tools aren’t immediately recognizing the new space.

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