ZFS-on-WSL

ZFS? In my WSL? ... It's more likely than you think.

This is a set of scripts and methods for building a WSL2 kernel and the corresponding userspace utilities necessary to support ZFS within WSL.

This does work, but it's quick and nasty so this is your obligatory warning not to rely on it for anything production-grade.

There are two ways of working with the files in this repo -

1. Self-building by running ./build_wsl_kernel.sh directly inside of an Ubuntu WSL environment.
2. Simply downloading the pre-built files that GitLab CI generates from this repo.

The instructions below are written with the assumption that you are downloading the files straight from this repo, but should be reasonably easy to follow without much modification if you are running the build script locally yourself.

Installation Procedure

Stop the WSL2 VM:

wsl --shutdown

Download the kernel bzImage and copy it somewhere convenient:

C:\ZFSonWSL\bzImage

Edit the .wslconfig file in your home directory to point to the downloaded kernel:

[wsl2]
kernel=C:\\ZFSonWSL\\bzImage
localhostForwarding=true
swap=0

Start up WSL again by opening a new WSL session and check that our custom kernel is being used:

$ uname -a
Linux L702X 5.13.9-penguins-rule #1 SMP Mon Aug 9 14:53:39 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Download the kernel and ZFS .tgz files and extract them. The commands below will put everything in /usr/src as we will need:

sudo tar -zxvf linux-5.13.9-penguins-rule.tgz -C /

sudo tar -zxvf zfs-2.1.0-for-5.13.9-penguins-rule.tgz -C /

Change directory into the kernel dir:

cd /usr/src/linux-5.13.9-penguins-rule/

Install our kernel modules:

sudo make modules_install

Change directory into the ZFS dir:

cd /usr/src/zfs-2.1.0-for-5.13.9-penguins-rule

Install our ZFS userspace utilities:

sudo make install

The command above should create the relevant files and links in /lib/modules for the built kernel modules.

You should now be able to insert the ZFS modules into the kernel without any issues:

sudo modprobe zfs

And you should be able to use the ZFS userspace utilities:

sudo zpool status

Now you can create ZFS pools within WSL2 by passing raw disks through to the WSL2 VM, as described by the Microsoft Docs for WSL.