How WSL Actually Packages and Distributes Linux Distros
Installing Ubuntu via the Microsoft Store feels like installing any other app. Underneath, WSL distros are root filesystem tarballs registered with a small platform layer — and that model is what makes import/export and custom distros possible.
Installing a Linux distro through WSL feels app-store-simple — pick Ubuntu or Debian from the Microsoft Store, click install, done. Underneath that simplicity is a genuinely straightforward packaging model: a root filesystem tarball plus a small amount of registration metadata.
What a “WSL distro” actually is, technically
At its core, a WSL distro is a root filesystem tarball (a compressed archive containing an entire Linux filesystem tree, similar in concept to what a container image’s filesystem layer contains) plus a small launcher application and registration with the WSL platform’s distro list — considerably simpler than it might seem from the Microsoft Store installation experience.
Why this makes exporting and importing distros straightforward
wsl --export Ubuntu ubuntu-backup.tar
wsl --import UbuntuCopy C:\WSL\UbuntuCopy ubuntu-backup.tarBecause a distro instance is fundamentally just a filesystem tarball plus registration, exporting one is literally packaging up its current filesystem state, and importing is registering a new distro instance from that same tarball — no more complex than that, which is why backup, cloning, and migration between machines work as cleanly as they do.
Why this also makes custom, non-Store distros possible
Since any root filesystem tarball can be imported as a distro, you’re not limited to the specific distros Microsoft or distro maintainers publish through the Store — a custom-built filesystem tarball (for a specialized environment, a specific team’s standardized dev environment, or an unofficial distro entirely) can be imported and used identically to an official one.
What actually gets stored where
Each imported or Store-installed distro instance’s filesystem lives in its own .vhdx virtual disk file under your Windows user profile — meaning multiple installed distros are genuinely separate filesystem instances, not shared installations, and each has its own independent state, packages, and configuration.
Why registration metadata matters beyond just the filesystem
The WSL platform layer tracks each registered distro’s default user, default working directory, and various per-distro settings separately from the filesystem tarball itself — which is why wsl --export and --import alone don’t perfectly preserve every configuration detail (default user, in particular, sometimes needs resetting after import) even though the underlying filesystem transfers completely.
What “cloning” a distro really means in this model
wsl --export Ubuntu temp.tar
wsl --import UbuntuClone C:\WSL\UbuntuClone temp.tarBecause import creates a genuinely independent distro instance from the exported tarball, this is real cloning — the new instance shares no ongoing state with the original after the import completes, unlike, say, a symlink or reference-based approach that would keep the two instances connected.
Why this simple underlying model is a genuine strength
A more complex, opaque distro installation mechanism would make backup, cloning, and custom-distro creation all considerably harder — the fact that a WSL distro reduces to “a filesystem tarball plus some registration metadata” is exactly what makes backing up and restoring a distro a straightforward, well-understood operation rather than something requiring specialized backup tooling.