Klara Systems is in the process of upstreaming a new ZFS vdev type.

Anyraid allows devices of mismatched sizes to be combined together into a single top-level vdev. In the current version, Anyraid only supports mirror-type parity, but raidz-type parity is planned for the near future. -- OpenZFS PR

This may take a while to merge and get released, but I'm excited to try this out.

Building With Nix#

nixpkgs packages several versions of zfs in the following manner

tree pkgs/os-specific/linux/zfs/
pkgs/os-specific/linux/zfs/
├── 2_2.nix
├── 2_3.nix
├── generic.nix
└── unstable.nix

generic.nix provides a function to compile zfs, and 2_2.nix, 2_3.nix and unstable.nix call this function supplying the hash.

So I could just:

• modify generic.nix to accept github owner and repository as argument since it's hard-coded to openzfs project
• fix the fact that master branch renamed arc_summary to zarcsummary
• add anyraid.nix with customized parameters
• add zfs_anyraid package wherever zfs_unstable is defined

See diff

NixOS Integration Testing#

nixpkgs contains some zfs tests, though none for anyraid vdev. However for sanity checking that it builds, I wanted to run the tests

nix run .#nixosTests.zfs.anyraid.driver

Deploying To A Server#

I then configure my fork as flake input nixpkgs-anyraid.url = "github:svistoi/nixpkgs/anyraid"; and build a server nixosConfigurations

with following options

boot.kernelPackages = lib.mkForce pkgs.linuxKernel.packages.linux_6_16;
boot.zfs.package = lib.mkForce pkgs.zfs_anyraid;
boot.supportedFilesystems = ["zfs"];
networking.hostId = "67262970";

The server configuration is out of scope of this. I've learned a lot about about flake layouts from some notable repositories:

• https://github.com/MatthewCroughan/nixcfg
• https://github.com/wimpysworld/nix-config
• https://github.com/srid/nixos-config
• https://github.com/jakehamilton/config

Creating A Pool With Anyraid vdev#

zpool create -f tank anyraid <list of devices>