How to Expand the Root Partition on CentOS 7 Using LVM in Simple Steps

Introduction

Linux servers often run out of disk space on the root partition. This guide demonstrates how to extend the root logical volume on a CentOS 7 system using LVM.

Step‑by‑Step Expansion

1. Check current disk usage

Use df -h to view the current usage; the root partition shows about 29 GB free.

2. Simulate a full root partition

Create a 29 GB file with dd to fill the root partition.

3. Add a new 60 GB disk

Physically attach a 60 GB disk to the server.

4. Identify the new disk

Use fdisk -l (or similar) to find the device name, e.g., /dev/xvdf.

5. Create a Physical Volume (PV)

Initialize the new disk as a PV without partitioning: pvcreate /dev/xvdf.

6. Extend the Volume Group (VG)

Find the VG that contains the root LV with lvs (e.g., centos) and add the new PV: vgextend centos /dev/xvdf. The VG now shows about 60 GB free.

7. Extend the root logical volume

Increase lv_root by 60 GB: lvextend -L +60G /dev/centos/root (or lvextend -l +100%FREE /dev/centos/root).

8. Resize the filesystem

Refresh the filesystem to use the new space, e.g., resize2fs /dev/centos/root for ext4 or xfs_growfs / for XFS.

9. Verify the expansion

Run df -Th to confirm the root partition now reflects the increased capacity.

After these steps the root partition is successfully expanded, allowing more storage for your Linux server.