ZFS: Difference between revisions

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== Known issues ==

* You shouldn't use a ZVol as a swap device, as it can deadlock under memory pressure.

* You should set the <code>mountpoint</code> property of your ZFS filesystems to be <code>legacy</code> and let NixOS mount them like any other filesystem (such as ''ext4'' or ''btrfs''), otherwise some filesystems may fail to mount due to ordering issues.

* All ZFS pools available to the system will be forcibly imported during boot, regardless if you had imported them before or not. You should be careful not to have any other system accessing them at the same time, otherwise it will corrupt your pools. Normally (for the common desktop user) this should not be a problem, as a hard disk is usually only directly connected to one machine.

* Using NixOS on a ZFS root file system might result in the boot error ''external pointer tables not supported'' when the number of hardlinks in the nix store gets very high. This can be avoided by adding this option to your <code>configuration.nix</code> file:

boot.loader.grub.copyKernels = true;

</syntaxhighlight>

== Caveats ==

* (ZFS, unrelated to Nix- see https://github.com/openzfs/zfs/issues/7734) You shouldn't use a ZVol as a swap device, as it can deadlock under memory pressure.

* You should set the <code>mountpoint</code> property of your ZFS filesystems to be <code>legacy</code> and let NixOS mount them like any other filesystem (such as ''ext4'' or ''btrfs''), otherwise some filesystems may fail to mount due to ordering issues.

* All ZFS pools available to the system will be forcibly imported during boot, regardless if you had imported them before or not. You should be careful not to have any other system accessing them at the same time, otherwise it will corrupt your pools. Normally (for the common desktop user) this should not be a problem, as a hard disk is usually only directly connected to one machine.

== How to use it ==

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 == Known issues ==
-* You shouldn't use a ZVol as a swap device, as it can deadlock under memory pressure.
-* You should set the <code>mountpoint</code> property of your ZFS filesystems to be <code>legacy</code> and let NixOS mount them like any other filesystem (such as ''ext4'' or ''btrfs''), otherwise some filesystems may fail to mount due to ordering issues.
-* All ZFS pools available to the system will be forcibly imported during boot, regardless if you had imported them before or not. You should be careful not to have any other system accessing them at the same time, otherwise it will corrupt your pools. Normally (for the common desktop user) this should not be a problem, as a hard disk is usually only directly connected to one machine.
 * Using NixOS on a ZFS root file system might result in the boot error ''external pointer tables not supported'' when the number of hardlinks in the nix store gets very high. This can be avoided by adding this option to your <code>configuration.nix</code> file:
 <syntaxhighlight lang="nix">
 boot.loader.grub.copyKernels = true;
 </syntaxhighlight>
+== Caveats ==
+* (ZFS, unrelated to Nix- see https://github.com/openzfs/zfs/issues/7734) You shouldn't use a ZVol as a swap device, as it can deadlock under memory pressure.
+* You should set the <code>mountpoint</code> property of your ZFS filesystems to be <code>legacy</code> and let NixOS mount them like any other filesystem (such as ''ext4'' or ''btrfs''), otherwise some filesystems may fail to mount due to ordering issues.
+* All ZFS pools available to the system will be forcibly imported during boot, regardless if you had imported them before or not. You should be careful not to have any other system accessing them at the same time, otherwise it will corrupt your pools. Normally (for the common desktop user) this should not be a problem, as a hard disk is usually only directly connected to one machine.
 == How to use it ==