ZFS: Difference between revisions
imported>Thblt m Typo |
improve module that selects the oldest kernel. |
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[https://zfsonlinux.org/ {{PAGENAME}}] ([[wikipedia:en:{{PAGENAME}}]]) - also known as [https://openzfs.org/ OpenZFS] ([[wikipedia:en:OpenZFS]]) - is a modern filesystem which is well supported on [[NixOS]]. | [https://zfsonlinux.org/ {{PAGENAME}}] ([[wikipedia:en:{{PAGENAME}}]]) - also known as [https://openzfs.org/ OpenZFS] ([[wikipedia:en:OpenZFS]]) - is a modern filesystem[[category:filesystem]] which is well supported on [[NixOS]]. | ||
Besides the ''zfs'' package (''ZFS Filesystem Linux Kernel module'') <ref>https://search.nixos.org/packages?channel=unstable&show=zfs&query=zfs</ref> itself there are many packages in the [[{{PAGENAME}}]] ecosystem available. | |||
[[{{PAGENAME}}]] integrates into NixOS via | [[{{PAGENAME}}]] integrates into NixOS via the ''boot.zfs''<ref>https://search.nixos.org/options?channel=unstable&query=boot.zfs</ref> and ''service.zfs''<ref>https://search.nixos.org/options?channel=unstable&query=services.zfs</ref> options. | ||
== Limitations == | == Limitations == | ||
==== | ==== Latest kernel compatible with ZFS ==== | ||
Newer kernels might not be supported by ZFS yet. If you are running a kernel which is not officially supported by zfs, the module will refuse to evaluate and show an error. | |||
You can pin to a newer kernel version explicitly, but note that this version may be dropped by upstream and in nixpkgs prior to zfs supporting the next version. See [[Linux kernel]] for more information.<syntaxhighlight lang="nix"> | |||
{ | |||
boot.kernelPackages = pkgs.linuxPackages_latest; | |||
# OR | |||
boot.kernelPackages = pkgs.linuxPackages_6_6 | |||
} | |||
</syntaxhighlight> | |||
This snippet will configure the latest compatible kernel. | |||
Note that this can over time jump back to old kernel versions because non-lts kernel version | |||
get removed over time and their newer replacements might be not supported by zfs yet. | |||
= | <syntaxhighlight lang="nix"> | ||
{ | |||
lib, | |||
pkgs, | |||
config, | |||
... | |||
}: | |||
If you are | let | ||
isUnstable = config.boot.zfs.package == pkgs.zfsUnstable; | |||
zfsCompatibleKernelPackages = lib.filterAttrs ( | |||
name: kernelPackages: | |||
(builtins.match "linux_[0-9]+_[0-9]+" name) != null | |||
&& (builtins.tryEval kernelPackages).success | |||
&& ( | |||
(!isUnstable && !kernelPackages.zfs.meta.broken) | |||
|| (isUnstable && !kernelPackages.zfs_unstable.meta.broken) | |||
) | |||
) pkgs.linuxKernel.packages; | |||
latestKernelPackage = lib.last ( | |||
lib.sort (a: b: (lib.versionOlder a.kernel.version b.kernel.version)) ( | |||
builtins.attrValues zfsCompatibleKernelPackages | |||
) | |||
); | |||
in | |||
{ | |||
# Note this might jump back and worth as kernel get added or removed. | |||
boot.kernelPackages = latestKernelPackage; | |||
} | |||
</syntaxhighlight> | |||
==== Partial support for SWAP on ZFS ==== | |||
ZFS does not support swapfiles. SWAP devices can be used instead. Additionally, hibernation is disabled by default due to a [https://github.com/NixOS/nixpkgs/pull/208037 high risk] of data corruption. Note that even if that pull request is merged, it does not fully mitigate the risk. If you wish to enable hibernation regardless and made sure that not swapfiles on ZFS are used, set <code>boot.zfs.allowHibernation = true</code>. | |||
==== Zpool not found ==== | |||
If NixOS fails to import the zpool on reboot, you may need to add <syntaxhighlight lang="nix" inline>boot.zfs.devNodes = "/dev/disk/by-path";</syntaxhighlight> or <syntaxhighlight lang="nix" inline>boot.zfs.devNodes = "/dev/disk/by-partuuid";</syntaxhighlight> to your configuration.nix file. | |||
The differences can be tested by running <code>zpool import -d /dev/disk/by-id</code> when none of the pools are discovered, eg. a live iso. | |||
==== declarative mounting of ZFS datasets ==== | ==== declarative mounting of ZFS datasets ==== | ||
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== Guides == | == Guides == | ||
==== '''OpenZFS Documentation for installing''' ==== | |||
{{warning|This guide is not endorsed by NixOS and some features like immutable root do not have upstream support and could break on updates. If an issue arises while following this guide, please consult the guides support channels.}} | {{warning|This guide is not endorsed by NixOS and some features like immutable root do not have upstream support and could break on updates. If an issue arises while following this guide, please consult the guides support channels.}} | ||
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* Give understandable, easy to follow and close to the standard installation guide instructions | * Give understandable, easy to follow and close to the standard installation guide instructions | ||
* integrating ZFS into your existing config | * integrating ZFS into your existing config | ||
==== '''Simple NixOS ZFS in root installation''' ==== | |||
Start from here in the NixOS manual: [https://nixos.org/manual/nixos/stable/#sec-installation-manual]. | |||
Under manual partitioning [https://nixos.org/manual/nixos/stable/#sec-installation-manual-partitioning] do this instead: | |||
'''Partition your disk with your favorite partition tool.''' | |||
We need the following partitions: | |||
* 1G for boot partition with "boot" as the partition label (also called name in some tools) and ef00 as partition code | |||
* 4G for a swap partition with "swap" as the partition label and 8200 as partition code. We will encrypt this with a random secret on each boot. | |||
* The rest of disk space for zfs with "root" as the partition label and 8300 as partition code (default code) | |||
Reason for swap partition: ZFS does use a caching mechanism that is different from the normal Linux cache infrastructure. | |||
In low-memory situations, ZFS therefore might need a bit longer to free up memory from its cache. The swap partition will help with that. | |||
Example with gdisk: | |||
<syntaxhighlight lang="bash"> | |||
sudo gdisk /dev/nvme0n1 | |||
GPT fdisk (gdisk) version 1.0.10 | |||
... | |||
# boot partition | |||
Command (? for help): n | |||
Partition number (1-128, default 1): | |||
First sector (2048-1000215182, default = 2048) or {+-}size{KMGTP}: | |||
Last sector (2048-1000215182, default = 1000215175) or {+-}size{KMGTP}: +1G | |||
Current type is 8300 (Linux filesystem) | |||
Hex code or GUID (L to show codes, Enter = 8300): ef00 | |||
Changed type of partition to 'EFI system partition' | |||
# Swap partition | |||
Command (? for help): n | |||
Partition number (2-128, default 2): | |||
First sector (2099200-1000215182, default = 2099200) or {+-}size{KMGTP}: | |||
Last sector (2099200-1000215182, default = 1000215175) or {+-}size{KMGTP}: +4G | |||
Current type is 8300 (Linux filesystem) | |||
Hex code or GUID (L to show codes, Enter = 8300): 8200 | |||
Changed type of partition to 'Linux swap' | |||
# root partition | |||
Command (? for help): n | |||
Partition number (3-128, default 3): | |||
First sector (10487808-1000215182, default = 10487808) or {+-}size{KMGTP}: | |||
Last sector (10487808-1000215182, default = 1000215175) or {+-}size{KMGTP}: | |||
Current type is 8300 (Linux filesystem) | |||
Hex code or GUID (L to show codes, Enter = 8300): | |||
Changed type of partition to 'Linux filesystem' | |||
# write changes | |||
Command (? for help): w | |||
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING | |||
PARTITIONS!! | |||
Do you want to proceed? (Y/N): y | |||
OK; writing new GUID partition table (GPT) to /dev/nvme0n1. | |||
The operation has completed successfully. | |||
</syntaxhighlight> | |||
Final partition table | |||
<syntaxhighlight lang=bash> | |||
Number Start (sector) End (sector) Size Code Name | |||
1 2048 2099199 1024.0 MiB EF00 EFI system partition | |||
2 2099200 10487807 4.0 GiB 8200 Linux swap | |||
3 10487808 1000215175 471.9 GiB 8300 Linux filesystem | |||
</syntaxhighlight> | |||
'''Let's use variables from now on for simplicity. | |||
Get the device ID in <code>/dev/disk/by-id/</code>, in our case here it is <code>nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O</code> | |||
''' | |||
<syntaxhighlight lang=bash> | |||
BOOT=/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part1 | |||
SWAP=/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part2 | |||
DISK=/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part3 | |||
'''Make zfs pool with encryption and mount points:''' | |||
'''Note:''' zpool config can significantly affect performance (especially the ashift option) so you may want to do some research. The [https://jrs-s.net/2018/08/17/zfs-tuning-cheat-sheet/ ZFS tuning cheatsheet] or [https://wiki.archlinux.org/title/ZFS#Storage_pools ArchWiki] is a good place to start. | |||
<syntaxhighlight lang="bash"> | |||
zpool create -O encryption=on -O keyformat=passphrase -O keylocation=prompt -O compression=zstd -O mountpoint=none -O xattr=sa -O acltype=posixacl -o ashift=12 zpool $DISK | |||
# enter the password to decrypt the pool at boot | |||
Enter new passphrase: | |||
Re-enter new passphrase: | |||
# Create datasets | |||
zfs create zpool/root | |||
zfs create zpool/nix | |||
zfs create zpool/var | |||
zfs create zpool/home | |||
mkdir -p /mnt | |||
mount -t zfs zpool/root /mnt -o zfsutil | |||
mkdir /mnt/nix /mnt/var /mnt/home | |||
mount -t zfs zpool/nix /mnt/nix -o zfsutil | |||
mount -t zfs zpool/var /mnt/var -o zfsutil | |||
mount -t zfs zpool/home /mnt/home -o zfsutil | |||
</syntaxhighlight> | |||
Output from <syntaxhighlight lang="bash" inline>zpool status</syntaxhighlight>: | |||
<syntaxhighlight > | |||
zpool status | |||
pool: zpool | |||
state: ONLINE | |||
... | |||
config: | |||
NAME STATE READ WRITE CKSUM | |||
zpool ONLINE 0 0 0 | |||
nvme-eui.0025384b21406566-part2 ONLINE 0 0 0 | |||
</syntaxhighlight> | |||
'''Format boot partition with fat as filesystem''' | |||
<syntaxhighlight lang="bash"> | |||
mkfs.fat -F 32 -n boot $BOOT | |||
</syntaxhighlight> | |||
'''Enable swap''' | |||
<syntaxhighlight lang="bash"> | |||
mkswap -L swap $SWAP | |||
swapon $SWAP | |||
</syntaxhighlight> | |||
'''Installation:''' | |||
# Mount boot | |||
<syntaxhighlight lang="bash"> | |||
mkdir -p /mnt/boot | |||
mount $BOOT /mnt/boot | |||
# Generate the nixos config | |||
nixos-generate-config --root /mnt | |||
... | |||
writing /mnt/etc/nixos/hardware-configuration.nix... | |||
writing /mnt/etc/nixos/configuration.nix... | |||
For more hardware-specific settings, see https://github.com/NixOS/nixos-hardware. | |||
</syntaxhighlight> | |||
Now edit the configuration.nix that was just created in <code>/mnt/etc/nixos/configuration.nix</code> and make sure to have at least the following content in it. | |||
<syntaxhighlight lang="nix"> | |||
{ | |||
... | |||
# Boot loader config for configuration.nix: | |||
boot.loader.systemd-boot.enable = true; | |||
# for local disks that are not shared over the network, we don't need this to be random | |||
networking.hostId = "8425e349"; | |||
... | |||
</syntaxhighlight> | |||
Now check the hardware-configuration.nix in <code>/mnt/etc/nixos/hardware-configuration.nix</code> and add whats missing e.g. <code>options = [ "zfsutil" ]</code> for all filesystems except boot and <code>randomEncryption = true;</code> for the swap partition. Also change the generated swap device to the partition we created e.g. <code>/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part2</code> in this case and <code>/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part1</code> for boot. | |||
<syntaxhighlight lang="nix"> | |||
... | |||
fileSystems."/" = { | |||
device = "zpool/root"; | |||
fsType = "zfs"; | |||
# the zfsutil option is needed when mounting zfs datasets without "legacy" mountpoints | |||
options = [ "zfsutil" ]; | |||
}; | |||
fileSystems."/nix" = { | |||
device = "zpool/nix"; | |||
fsType = "zfs"; | |||
options = [ "zfsutil" ]; | |||
}; | |||
fileSystems."/var" = { | |||
device = "zpool/var"; | |||
fsType = "zfs"; | |||
options = [ "zfsutil" ]; | |||
}; | |||
fileSystems."/home" = { | |||
device = "zpool/home"; | |||
fsType = "zfs"; | |||
options = [ "zfsutil" ]; | |||
}; | |||
fileSystems."/boot" = { | |||
device = "/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part1"; | |||
fsType = "vfat"; | |||
}; | |||
swapDevices = [{ | |||
device = "/dev/disk/by-id/nvme-SKHynix_HFS512GDE9X081N_FNB6N634510106K5O-part2"; | |||
randomEncryption = true; | |||
}]; | |||
} | |||
</syntaxhighlight> | |||
Now you may install nixos with <code>nixos-install</code> | |||
== Importing on boot == | == Importing on boot == | ||
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}; | }; | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Zpool created with bus-based disk names === | |||
If you used bus-based disk names in the <syntaxhighlight inline>zpool create</syntaxhighlight> command, e.g., <syntaxhighlight inline>/dev/sda</syntaxhighlight>, NixOS may run into issues importing the pool if the names change. Even if the pool is able to be mounted (with <syntaxhighlight lang="nix" inline>boot.zfs.devNodes = "/dev/disk/by-partuuid";</syntaxhighlight> set), this may manifest as a <syntaxhighlight inline>FAULTED</syntaxhighlight> disk and a <syntaxhighlight inline>DEGRADED</syntaxhighlight> pool reported by <syntaxhighlight inline>zpool status</syntaxhighlight>. The fix is to re-import the pool using disk IDs: | |||
<syntaxhighlight> | |||
# zpool export zpool_name | |||
# zpool import -d /dev/disk/by-id zpool_name | |||
</syntaxhighlight> | |||
The import setting is reflected in <syntaxhighlight inline="" lang="bash">/etc/zfs/zpool.cache</syntaxhighlight>, so it should persist through subsequent boots. | |||
=== Zpool created with disk IDs === | |||
If you used disk IDs to refer to disks in the <code>zpool create</code> command, e.g., <code>/dev/disk/by-id</code>, then NixOS may consistently fail to import the pool unless <code>boot.zfs.devNodes = "/dev/disk/by-id"</code> is also set. | |||
== Mount datasets at boot == | == Mount datasets at boot == | ||
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# Add the load-key command to the .profile | # Add the load-key command to the .profile | ||
echo "zfs load-key -a; killall zfs" >> /root/.profile | echo "zfs load-key -a; killall zfs" >> /root/.profile | ||
''; | |||
}; | }; | ||
}; | }; |