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Btrfs

Description

Btrfs is a modern copy on write (COW) file system for Linux aimed at implementing advanced features while also focusing on fault tolerance, repair and easy administration.

Directory

References

Timeshift with Btrfs

Description

Timeshift for Linux is an application that provides functionality similar to the System Restore feature in Windows and the Time Machine tool in macOS. This details how to setup and use Timeshift with Btrfs.

References

Steps

  1. Install the timeshift package using yay.

  2. Install the timeshift-autosnap package using yay to automatically create a snapshot every pre-upgrade.

  3. Install the grub-btrfs package using yay to allow booting into snapshots through Grub.

  4. Complete the setup through the Timeshift wizard:

    • Authenticate (as it requires sudo).

    • Select BTRFS as Snapshot Type.

    • Select the main btrfs partition as the Snapshot Location.

    • Select the desired Snapshot Levels. Default options are fine.

    • Leave the Include @home subvolume in backups option unchecked.

    • Click Finish.

  5. Create the first snapshot by clicking the Create button.

  6. Start and Enable the system's cron service (i.e. cronie.service) so that scheduled backups work.

  7. Regenerate a new GRUB config so that grub-btrfs works as intended.

Notes

  • timeshift-autosnap should only keep 3 older snapshots by default according to its config, /etc/timeshift-autosnap.conf.

  • If it is not working reliably, it is recommended for you to use the Timeshift desktop application to delete older snapshots manually from time to time.

Balance Btrfs Volumes

Description

If you are using a Btrfs filesystem, it is recommended for you to "balance" your Btrfs volumes on a monthly basis in order to ensure that the free space available on your device is properly unallocated.

Warning

Leaving your Btrfs volume unbalanced for too long might cause you No space left errors in the long run.

Steps

  1. Install the btrfs-assistant application using yay.

  2. Launch the btrfs-assistant application. You will be asked to authenticate (as it requires root permissions).

  3. Click the Start button in the Balance section to balance your Btrfs volumes.

Swap

Description

This guide covers topics pertaining to the addition or removal of swap files as virtual memory on a system running BTRFS.

References

Enable Swap

This details how to add and enable a swap file on a system running BTRFS:

  1. First, verify that swap is currently disabled on the system:

    • First method:

      inxi -j

      Sample output:

        Swap:
    Alert: No swap data was found.

    • Second method:

      swapon --show

      This command should not return any output.

  2. Ensure there is not a BTRFS subvolume for the swap file already:

    sudo btrfs subvolume list /

    Sample output:

      ID 257 gen 5349724 top level 5 path @home
  ID 258 gen 5349702 top level 5 path @cache
  ID 259 gen 5349717 top level 5 path @log
  ID 457 gen 5349724 top level 5 path @

  3. Determine the UUID of the BTRFS filesystem on the system:

    sudo btrfs filesystem show /

    Sample output:

      Label: 'endeavouros'  uuid: bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg
          Total devices 1 FS bytes used 290.02GiB
          devid    1 size 446.15GiB used 315.07GiB path /dev/sdb2

    Based on this sample output, the UUID of the BTRFS filesystem is bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg.

  4. Create a BTRFS subvolume to store the swap file:

    • Mount the BTRFS filesystem root temporarily to a mountpoint (i.e. /mnt):

      sudo mount UUID=<uuid> /mnt

      Replace <uuid> with the UUID of the BTRFS filesystem (i.e. bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg). For example:

      sudo mount UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /mnt

      This is done so we could access the top level where other BTRFS subvolumes are created on the system.

    • Create the swap BTRFS subvolume on the mountpoint (i.e. /mnt):

      sudo btrfs subvolume create /mnt/@swap

    • Ensure the swap BTRFS subvolume has been created:

      sudo btrfs subvolume list / | grep swap

      Sample output:

      ID 260 gen 344318 top level 5 path @swap

    • Unmount the BTRFS filesystem root from the mountpoint (i.e. /mnt):

      sudo umount /mnt

  5. Mount the swap BTRFS subvolume on the system (temporarily) and create the swap file:

    • Create a directory where the swap BTRFS subvolume should be mounted to (i.e. /swap):

      sudo mkdir /swap

    • Mount the swap BTRFS subvolume to the designated mountpoint (i.e. /swap):

      sudo mount -o subvol=/@swap,noatime UUID=<uuid> /swap

      Replace <uuid> with the UUID of the BTRFS filesystem (i.e. bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg). For example:

      sudo mount -o subvol=/@swap,noatime UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /swap

      Verify that it's mounted:

        TARGET SOURCE            FSTYPE OPTIONS
  /swap  /dev/sdb2[/@swap] btrfs  rw,noatime,compress=zstd:3,ssd,discard=async,space_cache=v2,subvolid=260,subvol=/@swap

    • Create the appropriately sized swap file on the mountpoint (i.e. /swap):

      sudo btrfs filesystem mkswapfile --size <size>g --uuid clear /swap/swapfile

      Replace <size> with the desired size of the swap file in gigabytes. If in doubt, allocate the size of your total system memory, or half of it. For example, for 16GB of swap:

      sudo btrfs filesystem mkswapfile --size 16g --uuid clear /swap/swapfile

    • Activate the swap file (i.e. /swap/swapfile) as swap space on the system:

      sudo swapon /swap/swapfile

  6. Verify that swap has been enabled on the system:

    • First method:

      inxi -j

      Sample output:

        Swap:
    ID-1: swap-1 type: file size: 16 GiB used: 10.2 MiB (0.1%)
      file: /swap/swapfile

    • Second method:

      swapon --show

      Sample output:

        NAME           TYPE SIZE  USED PRIO
  /swap/swapfile file  16G 10.5M   -2

  7. Mount the swap BTRFS subvolume on the system and activate the swap file on boot automatically:

    • Update the system's fstab file:

      sudo nano /etc/fstab

    • Add the following line to the fstab file, with the rest of the existing entries, to mount the swap BTRFS subvolume on boot to the designated mountpoint (i.e. /swap):

        UUID=<uuid> /var/log       btrfs   subvol=/@log,noatime,compress=zstd 0 0
+ UUID=<uuid> /swap          btrfs   subvol=/@swap,noatime              0 0

      Replace <uuid> with the UUID of the BTRFS filesystem (i.e. bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg). For example:

      UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /swap          btrfs   subvol=/@swap,noatime              0 0

    • Add the following line to the fstab file to activate the swap file we had created as swap space on boot (i.e. /swap/swapfile):

        UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /swap          btrfs   subvol=/@swap,noatime              0 0
+ /swap/swapfile                            swap           swap    defaults

      Sample entry:

      /swap/swapfile                            swap           swap    defaults

    • Upon next boot, the swap BTRFS subvolume will be mounted and the swap file will be activated accordingly.

Resize Swap

Note

This guide assumes that you have previously enabled swap on the system, and have not disabled it.

This details how to resize a swap file on a system running BTRFS:

  1. First, verify that swap is currently enabled on the system:

    • First method:

      inxi -j

      Sample output:

        Swap:
    ID-1: swap-1 type: file size: 16 GiB used: 10.2 MiB (0.1%)
      file: /swap/swapfile

    • Second method:

      swapon --show

      Sample output:

        NAME           TYPE SIZE  USED PRIO
  /swap/swapfile file  16G 10.5M   -2

  2. Disable the swap file (i.e. /swap/swapfile) on the system, temporarily:

    sudo swapoff /swap/swapfile

  3. Delete the current swap file (i.e. /swap/swapfile):

    sudo rm /swap/swapfile

  4. Create the replacement, appropriately sized swap file (i.e. /swap/swapfile):

    sudo btrfs filesystem mkswapfile --size <size>g --uuid clear /swap/swapfile

    For example, for 32GB of swap space:

    sudo btrfs filesystem mkswapfile --size 32g --uuid clear /swap/swapfile

    Sample output:

      create swapfile /swap/swapfile size 32.00GiB (34359738368)

  5. Activate the swap file (i.e. /swap/swapfile) as swap space on the system:

    sudo swapon /swap/swapfile

  6. Verify that swap has been enabled on the system:

    • First method:

      inxi -j

      Sample output:

        Swap:
    ID-1: swap-1 type: file size: 32 GiB used: 983.3 MiB (3.0%)
       file: /swap/swapfile

    • Second method:

      swapon --show

      Sample output:

        NAME           TYPE SIZE   USED PRIO
  /swap/swapfile file  32G 987.1M   -2

Disable Swap

This details how to disable and remove a swap device on a system running BTRFS:

  1. First, verify that swap is indeed currently enabled on the system:

    • First method:

      inxi -j

      Sample output:

        Swap:
    ID-1: swap-1 type: file size: 512 MiB used: 511.8 MiB (100.0%)
      file: /swap/swapfile

    • Second method:

      swapon --show

      Sample output:

        NAME           TYPE SIZE   USED PRIO
  /swap/swapfile file 512M 511.8M   -2

      Take note of the name of the swap device on the system (i.e. /swap/swapfile).

  2. Disable the (file-based) swap device (i.e. /swap/swapfile):

    sudo swapoff /swap/swapfile

  3. Unmount the swap subvolume from its mountpoint (i.e. /swap):

    sudo umount /swap

    (Optional) You may also delete the mountpoint as it is no longer needed:

    sudo rm -r /swap

  4. Delete the swap BTRFS subvolume (i.e. @swap) using the Btrfs Assistant application:

    • Launch the Btrfs Assistant application. Install the btrfs-assistant package using yay if you do not have it already.

    • Navigate to the Subvolumes tab.

    • From the list of subvolumes, locate and highlight the swap BTRFS subvolume (i.e. @swap) by selecting it.

    • Click the Delete button.

    • When prompted to confirm, click the Yes button.

  5. Prevent the system from attempting to mount the deleted swap BTRFS subvolume and activate the swap file on boot:

    • Update the system's fstab file:

      sudo nano /etc/fstab

    • Remove or comment the following line that mounts the swap BTRFS subvolume to the designated mountpoint (i.e. /swap):

      - UUID=<uuid> /swap          btrfs   subvol=/@swap,noatime              0 0
+ #UUID=<uuid> /swap          btrfs   subvol=/@swap,noatime              0 0

      Replace <uuid> with the UUID of the BTRFS filesystem (i.e. bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg). For example:

      UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /swap          btrfs   subvol=/@swap,noatime              0 0

    • Add the following line to the fstab file to activate the swap file we had created as swap space on boot (i.e. /swap/swapfile):

      - /swap/swapfile                            swap           swap    defaults
+ #/swap/swapfile                            swap           swap    defaults

    • Sample entries after they have been disabled by commenting them:

      #UUID=bzxd1bo8-9nnb-ddet-qykk-qjdgr9yytybg /swap          btrfs   subvol=/@swap,noatime              0 0
#/swap/swapfile                            swap           swap    defaults

  6. Reboot the system and reuse the same step to verify that swap has been disabled.