Btrfs: Difference between revisions
imported>Onny Add section on transfer snapshot |
imported>Onny Add section on subvolumes |
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== Usage == | == Usage == | ||
=== Subvolume === | |||
Create a subvolume | |||
<syntaxhighlight lang="bash"> | |||
btrfs subvolume create /mnt/nixos | |||
</syntaxhighlight> | |||
=== Snapshots === | === Snapshots === | ||
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=== Transfer snapshot === | === Transfer snapshot === | ||
Sending the snapshot <code>/mnt/@nixos_snapshot_202302</code> compressed to a remote host via ssh at <code>root@192.168.178.110</code> and saving it to a subvolume mounted or directory at <code>/mnt/ | Sending the snapshot <code>/mnt/@nixos_snapshot_202302</code> compressed to a remote host via ssh at <code>root@192.168.178.110</code> and saving it to a subvolume mounted or directory at <code>/mnt/nixos</code> | ||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
sudo btrfs send /mnt/@nixos_snapshot_202302 | zstd | ssh root@192.168.178.110 'zstd -d | btrfs receive ' | sudo btrfs send /mnt/@nixos_snapshot_202302 | zstd | ssh root@192.168.178.110 'zstd -d | btrfs receive /mnt/nixos' | ||
</syntaxhighlight> | </syntaxhighlight> | ||
[[Category: Configuration]] | [[Category: Configuration]] | ||
Revision as of 00:52, 5 February 2023
btrfs is a modern copy on write (CoW) filesystem for Linux aimed at implementing advanced features while also focusing on fault tolerance, repair and easy administration.
Installation
Partition the disk
# printf "label: gpt\n,550M,U\n,,L\n" | sfdisk /dev/sdX
Format partitions and create subvolumes
# mkfs.fat -F 32 /dev/sdX1
# mkfs.btrfs /dev/sdX2
# mkdir -p /mnt
# mount /dev/sdX2 /mnt
# btrfs subvolume create /mnt/root
# btrfs subvolume create /mnt/home
# btrfs subvolume create /mnt/nix
# umount /mnt
Mount the partitions and subvolumes
# mount -o compress=zstd,subvol=root /dev/sdX2 /mnt
# mkdir /mnt/{home,nix}
# mount -o compress=zstd,subvol=home /dev/sdX2 /mnt/home
# mount -o compress=zstd,noatime,subvol=nix /dev/sdX2 /mnt/nix
# mkdir /mnt/boot
# mount /dev/sdX1 /mnt/boot
Install NixOS
# nixos-generate-config --root /mnt
# nano /mnt/etc/nixos/configuration.nix # manually add mount options
# nixos-install
Configuration
Compression
nixos-generate-config --show-hardware-config doesn't detect mount options automatically, so to enable compression, you must specify it and other mount options in a persistent configuration:
fileSystems = {
"/".options = [ "compress=zstd" ];
"/home".options = [ "compress=zstd" ];
"/nix".options = [ "compress=zstd" "noatime" ];
"/swap".options = [ "noatime" ];
};
Swap file
Optionally, create a separate subvolume for the swap file. Be sure to regenerate your hardware-configuration.nix if you choose to do this.
# mkdir -p /mnt
# mount /dev/sdXY /mnt
# btrfs subvolume create /mnt/swap
# umount /mnt
# mkdir /swap
# mount -o subvol=swap /dev/sdXY /swap
Then, create the swap file with copy-on-write and compression disabled:
# truncate -s 0 /swap/swapfile
# chattr +C /swap/swapfile
# btrfs property set /swap/swapfile compression none
# dd if=/dev/zero of=/swap/swapfile bs=1M count=4096
# chmod 0600 /swap/swapfile
# mkswap /swap/swapfile
Finally, add the swap file to your configuration and nixos-rebuild switch:
swapDevices = [ { device = "/swap/swapfile"; } ];
Usage
Subvolume
Create a subvolume
btrfs subvolume create /mnt/nixos
Snapshots
Taking a read-only (-r) snapshot called nixos_snapshot_202302 of the subvolume mounted at /
btrfs subvolume snapshot -r / /mnt/@nixos_snapshot_202302
List snapshots for /
sudo btrfs subvolume list /
Transfer snapshot
Sending the snapshot /mnt/@nixos_snapshot_202302 compressed to a remote host via ssh at root@192.168.178.110 and saving it to a subvolume mounted or directory at /mnt/nixos
sudo btrfs send /mnt/@nixos_snapshot_202302 | zstd | ssh root@192.168.178.110 'zstd -d | btrfs receive /mnt/nixos'