= OpenZFS =

'''OpenZFS''', formerly '''ZFS on Linux''', is a project aimed at bringing the ZFS [[Linux/FileSystems|file system]] to the [[Linux]] kernel.

If using a [[BSD]], ZFS should be supported out of the box.

<<TableOfContents>>

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== Installation ==



=== Arch ===

The first step is almost always downgrading the kernel.

{{{
version=major.minor.patch-release
sudo pacman -U https://archive.archlinux.org/packages/l/linux-lts/linux-lts-$version-x86_64.pkg.tar.zst https://archive.archlinux.org/packages/l/linux-lts-headers/linux-lts-headers-$version-x86_64.pkg.tar.zst
sudo mkinitcpio -P
sudo grub-mkconfig -o /boot/grub/grub.cfg
}}}

To determine which kernel version is supported, try installing ZFS from the [[Linux/Arch/Pacman#Repositories|unofficial repository]].

{{{
sudo pacman-key -r DDF7DB817396A49B2A2723F7403BD972F75D9D76
sudo pacman-key --lsign-key DDF7DB817396A49B2A2723F7403BD972F75D9D76
sudo bash -c 'echo "[archzfs]\nServer = https://archzfs.com/$repo/$arch\n" >> /etc/pacman.conf'
sudo pacman -Syu archzfs-linux
}}}

If the last command gives an error about an unsatisfiable dependency involving the kernel, the indicated version is what to use in the above snippet.

With a supported kernel and the ZFS module installed, try booting.

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== Pools ==

The lowest level of ZFS is '''pools'''.

Identify disks by their IDs like:

{{{
$ ls -lh /dev/disk/by-id/
total 0
lrwxrwxrwx 1 root root 1 Jan 01 12:30 ata-ABCDE
lrwxrwxrwx 1 root root 1 Jan 01 12:30 ata-FGHIJ
lrwxrwxrwx 1 root root 1 Jan 01 12:30 ata-KLMNO
lrwxrwxrwx 1 root root 1 Jan 01 12:30 ata-PQRST
}}}

With these 4 drives of ''N'' GB storage each, create a '''RAIDz2''' pool where ''2N'' GB will be dedicated to parity rather than storage. The pool will be fault tolerant for up to 2 failed drives.

{{{
sudo zpool create -f tank raidz2 ata-ABCDE ata-FGHIJ ata-KLMNO ata-PQRST
}}}

Alternatively create a '''RAIDz1''' pool where just ''N'' GB will be dedicated to parity (but the pool will only be fault tolerant of 1 drive failure).

''Alternatively'' alternatively, create a '''Mirror''' pool to maximize fault tolerance (up to 3 failed drives) but leaving just ''N'' GB of storage.

Pools can be created with encryption, but it is not recommended. A pool's encryption setting is inherited, so the pool is permanently locked to this singular cryptographic algorithm.

The pool will be mounted to a root-level directory named after the pool (`/tank` in this case).

Check the status of pools with `zpool status`.

To ensure that the pools mount at boot, try:

{{{
sudo systemctl enable zfs-import-cache.service zfs.target zfs-import.target
}}}

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== Datasets ==

To create a dataset within a pool, try:

{{{
sudo zfs create tank/data
}}}

To create an encrypted dataset, try:

{{{
sudo zfs create -o encryption=on -o keyformat=passphrase tank/enc
}}}

The default cryptographic algorithm is `aes-256-gcm`.

To mount an encrypted dataset, try:

{{{
sudo zfs load-key tank/enc
sudo zfs mount tank/enc
}}}

----



== Administration ==

Consider disabling access times.

{{{
sudo zfs set atime=off tank
# or
sudo zfs set atime=off tank/data
}}}

Consider enabling compression. Upstream considers this to be a reasonable default, even for uncompressible files.

{{{
sudo zfs set compression=on tank
}}}

The default compression algorithm is `lz4`.

ZFS pools must be scrubbed to ensure that bit rot is addressed before backups are lost. To trigger this manually, try:

{{{
sudo zpool scrub tank
}}}

Alternatively, enable a [[Linux/Systemd|timer]] to automate this:

{{{
sudo systemctl enable zfs-scrub-weekly@tank.timer
}}}



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