How To Resize XFS / Btrfs file systems on Linux

A Linux file system can be defined as a structured collection of files on a partition or disk. This is an in-built layer in the Linux Operating system that handles data management in the storage. Data is stored in a hierarchal structure with root directories and subdirectories in it. There are many supported file systems on Linux that include; EXT, EXT2, EXT3, EXT4, JFS, Swap, XFS, ReiserFS, Btrfs e.t.c

In this guide, we will walk through how to resize XFS / Btrfs file systems on Linux. The XFS file system is referred to as the high-speed JFS(Journaled File System). This file system is developed for parallel I/O processing. The Btrfs(B tree file system) is known for fault tolerance, extensive storage configuration, repair system e.t.c

Resizing file systems is different from resizing partitions/volumes which makes more space on the physical volume. When using the YaST Partitioner to resize logical volumes, the files systems are automatically adjusted to new sizes of the partition. However, in some cases, you might need to resize the file systems manually. The cases that you might need to resize the file system manually include:

• After resizing a virtual disk of a VM Guest.
• To shrink Btrfs file systems, YaST only supports growing Btrfs file systems
• After resizing a volume from a network-attached storage
• After resizing partitions manually with fdisk/parted

But remember, resizing file systems involves risks that potentially could lead to data loss. Therefore, it is highly recommended that you take a backup of the available data before you resize the file system. Below is a table to show Linux file systems that support resizing.

When growing/increasing a file system, you can specify the exact size to grow to or grow to the maximum space available. But before you grow the size of a file system, ensure the size of the logical volume/device has been grown. When shrinking or growing the file system by specifying the size, the following must be met:

• The new size must be greater than the size of the existing data. Otherwise, data loss will occur.
• The new size to grow must be equal to/less than the current device size since the file system size cannot extend beyond the available space.

1. Create the Partition/Logical Volume

I assume that you already have the partition/logical volume to grow. This guide will demonstrate how to resize an XFS file system by mounting another disk(sdb) and growing the volume:

$ lsblk
NAME               MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                  8:0    0   40G  0 disk 
├─sda1               8:1    0    1G  0 part /boot
└─sda2               8:2    0   39G  0 part 
  ├─almalinux-root 253:0    0   35G  0 lvm  /
  └─almalinux-swap 253:1    0    4G  0 lvm  [SWAP]
sdb                  8:16   0   10G  0 disk 
sr0                 11:0    1 1024M  0 rom  

To identify the file system on your device, use the lsblk -f command.

Now create a partition table on the mounted disk.

sudo cfdisk /dev/sdb

Select dos type and proceed as below:

    Device        Boot       Start         End     Sectors   Size   Id Type
>>  Free space                2048    20971519    20969472    10G               

           [   New  ]  [  Quit  ]  [  Help  ]  [  Write ]  [  Dump  ]

Create a new partition with say 6GB size and leave some free space on your device.

Once that changes have been made, quit and proceed to verify if the partition has been created:

$ lsblk
NAME               MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                  8:0    0   40G  0 disk 
├─sda1               8:1    0    1G  0 part /boot
└─sda2               8:2    0   39G  0 part 
  ├─almalinux-root 253:0    0   35G  0 lvm  /
  └─almalinux-swap 253:1    0    4G  0 lvm  [SWAP]
sdb                  8:16   0   10G  0 disk 
└─sdb1               8:17   0    6G  0 part 
sr0                 11:0    1 1024M  0 rom  

Create the XFS/Btrfs file system on it.

##For XFS
sudo mkfs.xfs /dev/sdb1 -f

##For Btrfs
sudo mkfs.btrfs /dev/sdb1 -f

Mount the file:

sudo mkdir /mnt/datastore
sudo mount /dev/sdb1 /mnt/datastore
sudo mount | grep /dev/sdb1

Sample Output:

##For XFS
/dev/sdb1 on /mnt/datastore type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)

##For Btrfs
/dev/sdb1 on /mnt/datastore type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/)

I assume to have content in the path:

$ ls -al /mnt/datastore/
total 0
drwxr-xr-x. 4 root root 32 Apr 12 05:23 .
drwxr-xr-x. 3 root root 23 Apr 12 05:22 ..
drwxr-xr-x. 2 root root  6 Apr 12 05:23 new
drwxr-xr-x. 2 root root  6 Apr 12 05:23 new.txt

2. Grow the Partition/Logical Volume

First, check the current size of the partition.

$ df -h
Filesystem                  Size  Used Avail Use% Mounted on
devtmpfs                    1.8G     0  1.8G   0% /dev
tmpfs                       1.9G     0  1.9G   0% /dev/shm
tmpfs                       1.9G  9.2M  1.9G   1% /run
tmpfs                       1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mapper/almalinux-root   36G  4.6G   31G  14% /
/dev/sda1                  1014M  347M  668M  35% /boot
tmpfs                       374M   12K  374M   1% /run/user/42
tmpfs                       374M  4.0K  374M   1% /run/user/1000
/dev/sdb1                   6.0G   76M  6.0G   2% /mnt/datastore

Here, we will grow the /dev/sdb1 partition manually with fdisk to 10GB. Launch the utility tool and proceed to modify the partition to a new size:

sudo cfdisk /dev/sdb

Delete the partition.

3. Resize XFS/Btrfs file systems on Linux

Once you have grown the partition, proceed and resize the file systems as below.