XFS offers more modern features compared to EXT4 and performs better when handling large numbers of files

References: XFS vs EXT4, Why did CENTOS 7.0 choose XFS as the default filesystem? What are the advantages of XFS over ext?, Ext4 vs XFS – Which one to choose?

NOTE: Since XFS cannot shrink partitions, it’s recommended to use LVM for flexibility

Prerequisites: Arch Linux system with LVM+EXT4 disk management

Technical references: Change Root File System from Ext4 to Xfs on Archlinux, XFS (简体中文), LVM (简体中文)

Preparation

Backup system data and create Arch Linux Live environment

Preparing Filesystem

Reboot into Live environment

Shrink EXT4 Logical Volume

Compress Ext4 Partition

Reference: Resizing EXT4 partition safely

e2fsck -f /dev/<volume_group>/<physical_volume>
# Check the partition to be resized (required by EXT4 tools)

resize2fs /dev/<volume_group>/<physical_volume> 300G
# Resize filesystem to 300G

Shrink LVM Logical Volume

Reference: Shrinking logical volumes and their filesystems simultaneously

lvresize -L 300G /dev/<volume_group>/<physical_volume>
# Resize logical volume to 300G

Create LVM Logical Volume for XFS

Reference: Creating logical volumes (LV)

lvcreate -L 300G <volume_group> -n <xfs_physical_volume>
# Create a 300G logical volume

mkfs.xfs /dev/<volume_group>/<xfs_physical_volume>
# Format the volume with XFS filesystem

Data Migration

NOTE: Do not use cp for data copying as it changes setuid bits and follows hard links.

Using tar to Copy All Files

• Mount XFS and EXT4 partitions
• tar -cf - <EXT4_mount_path> | ( cd <XFS_mount_path> ; tar -xpvf - )

PS: You can use pv to monitor progress

Since tar cannot preserve SELinux labels (if any), ACLs and xattrs, use rsync for exact file copying.

Reference: How can a filesystem be copied exactly as is?

rsync -aviHAXKhPS <EXT4_dir> <XFS_dir>

System Configuration

Update GRUB2 Configuration

Mount Root and EFI Partitions

mount /dev/<volume_group>/<xfs_physical_volume> /mnt  # Mount XFS partition
mount /dev/<EFI_Partition> /mnt/boot/efi  # Mount EFI partition
arch-chroot /mnt  # Enter chroot environment

Verify Swapfile

If you use swapfile for system hibernation, reconfigure GRUB2 accordingly

Rebuild GRUB2 Configuration

grub-mkconfig -o /boot/grub/grub.cfg  # Rebuild GRUB2 config

Update Fstab File

Exit chroot environment

genfstab -U /mnt >> /mnt/etc/fstab  # Update file

vim /mnt/etc/fstab  # Remove/comment old EXT4 mount points

System Verification

Reboot and check if system boots normally

Check XFS Filesystem Status

Reference: XFS_(简体中文)#Data corruption

sudo xfs_scrub /  # Online error checking
sudo xfs_db -c frag -r /  # Check disk fragmentation

NOTE: If any errors are found, immediately enter Live environment for offline repair

xfs_repair -v /dev/<volume_group>/<xfs_physical_volume>

Check Error Logs

journalctl -p 3 -xb

Troubleshooting

LVM Mount Failure

Reference: LVM replace hard drive and move data smoothly

lvm vgchange -ay  # Activate all LVM groups
mount /dev/mapper/YOUR_LVM_NAME /new_root  # Replace YOUR_LVM_NAME with your LVM group name
exit  # Exit rescue mode and boot into system

XFS Fragmentation Issues

Enter Live system to repair filesystem

mount /dev/<volume_group>/<xfs_physical_volume> /mnt  # XFS requires mounting first
umount /mnt
xfs_repair -v /dev/<volume_group>/<xfs_physical_volume>  # Repair

Attempt defragmentation:

mount /dev/<volume_group>/<xfs_physical_volume> /mnt  # Defrag requires mounted partition
xfs_db -c frag -r /dev/<volume_group>/<xfs_physical_volume>  # Check fragmentation
xfs_fsr /dev/<volume_group>/<xfs_physical_volume>  # Defragment

XFS Mount Failure

Reference: mount: Structure needs cleaning. How to repair without losing data?

Enter Live system to repair filesystem:

mount /dev/<volume_group>/<xfs_physical_volume> /mnt  # Will fail due to corruption
xfs_repair -v -L /dev/<volume_group>/<xfs_physical_volume>  # Force clear journal and repair (may lose data)

NOTE

XFS cannot shrink partitions, but never attempt to shrink only the LVM logical volume without shrinking the partition.

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