Introduction

Linux disk management is one of the most important skills for system administrators and developers.

Many enterprise Linux distributions, including:

• Red Hat Enterprise Linux (RHEL)

• AlmaLinux

• Rocky Linux

• CentOS Stream

One common situation is:

• `/home` has too much unused space

• `/root` is running out of space

• The system partition needs expansion

Instead of reinstalling the operating system, we can safely:

1. Backup `/home`

2. Remove the old `/home` logical volume

3. Expand the root logical volume

4. Recreate `/home`

5. Restore user data

This article demonstrates the complete process.

Important Warnings Before Operation

Disk operations are powerful but dangerous.

A small mistake can make the system unbootable.

Before executing any command, carefully check the following.

1. Make Sure `/opt` Has Enough Backup Space

Potential Risk

The first step creates a complete `/home` backup:

tar -zcvf /opt/home.tar.gz -C /home .

The backup file is stored under /opt.

However, many Linux installations place /opt inside the root filesystem.

Example:

/
├── /opt
├── /etc
├── /var
└── /usr

If / is already almost full, the backup process may fail.

At that point:

/home data is not fully backed up

The migration process becomes dangerous

Check Available Space

Run:

df -h /opt

Make sure:

Available space > current /home usage

Example:

/home used: 60G

/opt available: 120G

This is safe.

2. Never Use a /home User for Remote SSH Operations

Critical Risk

Do not perform this migration while logged in as:

admin

user

developer

if the user's home directory is:

/home/admin

/home/user

Example:

SSH login
    |
    |
admin user
    |
    |
su -
    |
    |
root

This looks safe, but it is not.

When executing:

fuser -km /home

the system will terminate all processes using /home.

Your SSH session will immediately disappear.

The result can be:

SSH disconnected

Backup unfinished

Old volume removed

New volume not created

The server may become unusable.

Recommended Solutions

Use one of these methods:

Option 1

Enable direct root SSH login temporarily.

Option 2

Use a persistent terminal:

tmux

or:

screen

Run the migration inside that session.

3. Confirm Filesystem Type

This procedure uses:

mkfs.xfs

and:

xfs_growfs

Therefore the filesystem must be XFS.

Check:

df -T /home

Example:

Filesystem Type

/dev/mapper/almalinux-home xfs

Correct.

If you see:

ext4

do not continue.

Ext4 requires different tools.

Check Current Disk Layout

Before changing anything:

df -hT

Also check LVM structure:

lsblk

Example:

sda
 └─ almalinux-root
 └─ almalinux-home

Backup and Unmount /home

Create Backup

tar -zcvf /opt/home.tar.gz -C /home .

This creates:

/opt/home.tar.gz

containing all user data.

Stop Processes Using /home

fuser -km /home

Unmount /home

umount /home

Verify:

df -hT

Remove Old Home Logical Volume

Delete the old /home LV:

lvremove /dev/mapper/almalinux-home

Confirm when asked.

Expand Root Logical Volume

Use all remaining free space:

lvextend -l +100%FREE /dev/mapper/almalinux-root

Expand XFS Root Filesystem

xfs_growfs /dev/mapper/almalinux-root

Check:

df -h

The root filesystem should now be larger.

Create New 97GB Home Volume

Create a new /home logical volume:

lvcreate -L 97G -n home almalinux

Format it:

mkfs.xfs /dev/mapper/almalinux-home

Mount:

mount /dev/mapper/almalinux-home /home

Check:

df -h

Restore User Data

Extract backup:

tar -zxvf /opt/home.tar.gz -C /home/

Restore ownership:

chown -R jey:jey /home/jey/

AlmaLinux and RHEL Difference

For RHEL systems:

replace:

almalinux

with:

rhel

Example:

lvremove /dev/mapper/rhel-home
lvextend -l +100%FREE /dev/mapper/rhel-root
xfs_growfs /dev/mapper/rhel-root

Complete RHEL Example

df -hT

tar -zcvf /opt/home.tar.gz /home/*

fuser -km /home

umount /home

df -hT

lvremove /dev/mapper/rhel-home

lvextend -l +100%FREE /dev/mapper/rhel-root

xfs_growfs /dev/mapper/rhel-root

lvcreate -L 97G -n home rhel

mkfs.xfs /dev/mapper/rhel-home

mount /dev/mapper/rhel-home /home

df -h

tar -zxvf /opt/home.tar.gz -C /home/

chown -R jey:jey /home/jey/

Final Notes

This method is suitable for:

AlmaLinux

RHEL

Rocky Linux

CentOS Stream

with:

LVM

XFS filesystem

The most important rules:

1.Always backup first

2.Always operate as root

3.Never run from a /home user SSH session

4.Confirm filesystem type before resizing

5.Use tmux or screen for remote servers

With proper preparation, you can resize Linux storage layouts safely without reinstalling the operating system.