Linux Disk Expansion Guide

Increasing the disk size in your VM settings (VMware/VirtualBox) is only half the battle. The OS won’t automatically use that extra space until you manually update the partition table and the filesystem.

Here is a quick guide on how I expanded my /dev/sda2 partition from 30GB to 40GB without losing any data.

The Problem

After increasing the virtual disk to 40GB, running lsblk showed that the physical disk (sda) was 40GB, but the primary partition (sda2) was still stuck at 30GB.

# Output snippet
sda      8:0    0    40G  0 disk 
└─sda2   8:2    0    30G  0 part /

Step 1: Install the Growth Tools

We need growpart, a handy utility that can safely extend a partition while the system is running.

sudo apt update
sudo apt install cloud-guest-utils -y

Step 2: Extend the Partition

We tell the system to expand the 2nd partition of the sda disk. Note the space between the disk name and the partition number:

sudo growpart /dev/sda 2

Step 3: Resize the Filesystem

Now that the “room” (partition) is bigger, we need to stretch the “carpet” (filesystem) to cover the new floor space.

First, check your filesystem type:

df -T /

Depending on the output (ext4 or xfs), run the corresponding command:

For ext4 (Common in Ubuntu)

sudo resize2fs /dev/sda2

For xfs

sudo xfs_growfs /

Conclusion

Check the final result with df -h /. You should see the full capacity reflected in your root directory!

# Final check
/dev/sda2        40G   21G   17G  55% /

Key Takeaway

Always remember the three-layer hierarchy: Physical Disk → Partition Table → Filesystem. You must expand them in that specific order.