How to Safely Remove /home and Expand /root on CentOS with LVM

Removing /home

Backup /home partition files

# New system ignores
tar cvf /tmp/home.tar /home

Before uninstalling the /home filesystem, CentOS checks /etc/fstab at boot; because fstab contains a /home entry by default, you must comment it out to avoid boot failure.

Edit /etc/fstab

vim /etc/fstab
# Comment out the /home line
#/dev/mapper/centos-home /home xfs defaults 0 0

Install psmisc

yum install -y psmisc

The psmisc package provides utilities for managing the /proc directory, including fuser, killall, pstree, and pstree.x11.

fuser: shows PIDs of processes using a specified file or filesystem.

killall: terminates all processes with a given name.

pstree: displays a tree view of running processes.

pstree.x11: same as pstree but requires confirmation before exiting.

Unmount /home filesystem

umount /home

If unmount fails because a process is using /home, stop those processes:

fuser -km /home/

Remove the /home logical volume

lvremove /dev/mapper/centos-home

Expand root

Extend the LV that holds /root

Use vgdisplay to view free space after removing /home.

[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name               centos
...
Free PE / Size       61727 / 241.12 GiB

Free PE/Size indicates the space that can be added to /root.

lvextend -L +241G /dev/mapper/centos-root

After extending, df may still show the old size until the filesystem is grown.

[root@localhost ~]# df
Filesystem               1K-blocks    Used Available Use% Mounted on
/dev/mapper/centos-root   52403200 1813004 50590196   4% /
...

Extend the /root filesystem

xfs_growfs /dev/mapper/centos-root

Check root filesystem space

Finally, verify the new size with df -h:

[root@localhost ~]# df -h
Filesystem               Size Used Avail Use% Mounted on
/dev/mapper/centos-root  291G 1.8G 290G   1% /
...

Link: https://www.cnblogs.com/thankcat/p/18018048

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