ZFS: Difference between revisions
Add short command to know the difference between different disk/by-* paths
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(Add short command to know the difference between different disk/by-* paths) |
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[https://zfsonlinux.org/ {{PAGENAME}}] ([[wikipedia:en:{{PAGENAME}}]]) - also known as [https://openzfs.org/ OpenZFS] ([[wikipedia:en:OpenZFS]]) - is 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]]. | ||
There are a lot of packages for [[{{PAGENAME}}]]. For example there is the ''zfs'' package (''ZFS Filesystem Linux Kernel module'') itself.<ref>https://search.nixos.org/packages?channel=unstable&show=zfs&query=zfs</ref> But there are also a lot of packages of the [[{{PAGENAME}}]] ecosystem available. | There are a lot of packages for [[{{PAGENAME}}]]. For example there is the ''zfs'' package (''ZFS Filesystem Linux Kernel module'') itself.<ref>https://search.nixos.org/packages?channel=unstable&show=zfs&query=zfs</ref> But there are also a lot of packages of the [[{{PAGENAME}}]] ecosystem available. | ||
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Newest kernels might not be supported by ZFS yet. If you are running an newer kernel which is not yet officially supported by zfs, the zfs module will refuse to evaluate and show up as ''broken''. Use <code>boot.kernelPackages = config.boot.zfs.package.latestCompatibleLinuxPackages;</code> to use the latest compatible kernel. | Newest kernels might not be supported by ZFS yet. If you are running an newer kernel which is not yet officially supported by zfs, the zfs module will refuse to evaluate and show up as ''broken''. Use <code>boot.kernelPackages = config.boot.zfs.package.latestCompatibleLinuxPackages;</code> to use the latest compatible kernel. | ||
==== | ==== partial support for SWAP on ZFS ==== | ||
ZFS does not support swapfiles. | ZFS does not support swapfiles. SWAP devices must 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 / after that pull request is merged, it does not fully mitigate the risk. If you wish to enable hibernation regardless, set <code>boot.zfs.allowHibernation = true</code>. | ||
==== boot.zfs.devNodes | ==== boot.zfs.devNodes ==== | ||
If | 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 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 | |||
* 10G 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 output from fdisk: | |||
<syntaxhighlight lang="bash"> | |||
sudo gdisk /dev/nvme0n1 | |||
GPT fdisk (gdisk) version 1.0.9.1 | |||
... | |||
Command (? for help): p | |||
Disk /dev/nvme0n1: 500118192 sectors, 238.5 GiB | |||
Sector size (logical/physical): 512/512 bytes | |||
Disk identifier (GUID): CA926E8C-47F6-416A-AD1A-C2190CF5D1F8 | |||
Partition table holds up to 128 entries | |||
Main partition table begins at sector 2 and ends at sector 33 | |||
First usable sector is 34, last usable sector is 500118158 | |||
Partitions will be aligned on 2048-sector boundaries | |||
Total free space is 2669 sectors (1.3 MiB) | |||
Number Start (sector) End (sector) Size Code Name | |||
1 2048 2099199 1024.0 MiB EF00 boot | |||
2 2099200 23070719 10.0 GiB 8200 swap | |||
3 23070720 500117503 227.5 GiB 8300 root | |||
Command (? for help): | |||
</syntaxhighlight> | |||
'''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 /dev/nvme0n1p2 | |||
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> | |||
'''Make fat filesystem on boot partition''' | |||
<syntaxhighlight lang="bash"> | |||
mkfs.fat -F 32 -n boot /dev/nvme0n1p1 | |||
</syntaxhighlight> | |||
'''Installation:''' | |||
Install: [https://nixos.org/manual/nixos/stable/#sec-installation-manual-installing] | |||
Jump to "2. UEFI systems" | |||
<syntaxhighlight lang="bash"> | |||
mkdir -p /mnt/boot | |||
mount /dev/disk/by-partlabel/boot /mnt/boot | |||
</syntaxhighlight> | |||
Jump to "4." ... /mnt/etc/nixos/configuration.nix ... | |||
Continue from here and add this boot loader and filesystems config to your configuration.nix: | |||
<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"; | |||
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-partlabel/boot"; | |||
fsType = "vfat"; | |||
}; | |||
swapDevices = [{ | |||
device = "/dev/disk/by-partlabel/swap"; | |||
randomEncryption = true; | |||
}]; | |||
} | |||
</syntaxhighlight> | |||
== 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 | ||
''; | |||
}; | }; | ||
}; | }; |