How to resize logical volume(LVM) in arch

Suppose you want to resize your root by 20G, and reduce home by 20G, here is how you go about it.

Steps

1. Boot on a USB live key
2. Decrypt the luks volume

cryptsetup open /dev/nvme0n1p3 luks_lvm

3. Mount partitions (i just mounted everything incase you also wanted to

swapswapon /dev/mappper/arch-swap
swapon -a
mount /dev/mapper/arch-root /mnt
mkdir -p /mnt/{home,boot}
mount /dev/nvme0n1p2 /mnt/boot
mount /dev/mapper/arch-home /mnt/home
mount /dev/nvme0n1p1 /mnt/boot/efi

arch-chroot /mnt /bin/bash

Detect volume group

vgscan

Activate volume group “arch”

vgchange -a y arch

Shrink arch-home filesystem

incase you dont have btrfs installed

pacman -S btrfsutils

btrfs filesystem resize -20g /home

Do the same to the logical volume

lvresize -L -20g arch/home

Check to see free volume , as you can see its 20G. Now we will need to add it into root volume logical volumes and filesystem respectively

lvresize -L +20g arch/root

btrfs filesystem resize +20g /

Done. xD