# Reclaim disk space used by Docker Desktop (WSL2)

# Problem

I was always out of disk space in my C drive, and even though I clear my stuff often, I notice that my space is never reclaimed, instead, it kept going down.

I used [WizTree](https://diskanalyzer.com/) to view which file is taking up my disk space, and I noticed this

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1697900944923/e270efcb-3499-444d-a848-c670ff20c30c.png align="center")

Notice that in `%LOCALAPPDATA%\Docker\wsl\data`, there is a file `ext4.vhdx` that is taking up `64.6gb` of space, around `14%` of my total disk space.

> Docker Desktop for Windows uses WSL2 to manage all images and keep them in `ext4.vhdx`

So to reclaim the space, I tried to delete the docker images via `Docker Desktop` manually, but the space was not reclaimed even though I deleted most of the unused images.

Based on `portainer`, I am currently only using `4.1gb` of space where before the clean-up, I am using around `20+gb`.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1697901445817/56496467-20ab-4065-86e4-01cfed134526.png align="center")

# Solution - **Optimize-VHD**

Hyper-V has a command `Optimize-VHD` that optimizes the allocation of space used by virtual hard disk files. In short, it helps to shrink the space used by `Docker Desktop`.

To do so, exit `Docker Desktop`, and shutdown WSL by running

```bash
wsl --shutdown
```

Give it a minute, and run `wsl -l -v` and the distro should be in `stopped` state.

```bash
 wsl -l -v
  NAME                    STATE           VERSION
* Ubuntu                  Stopped         2
  docker-desktop          Stopped         2
  docker-desktop-data     Stopped         2
  rancher-desktop         Stopped         2
  rancher-desktop-data    Stopped         2
```

Navigate to the directory that stores `ext4.vhdx`, and run the following command

```bash
optimize-vhd -Path .\ext4.vhdx -Mode full
```

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1697901726031/4e363714-73d2-46db-ad9f-9fa9c0042e68.png align="center")

Give it some time to complete, it took around 5 min for me.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1697901981839/96ae0984-0d00-4b19-930c-6e8b4202daea.png align="center")

Viola! It reclaims nearly `40gb` of disk space for me.

It's a chore to keep reclaiming manually, but I've learned that WSL has a [new update](https://devblogs.microsoft.com/commandline/windows-subsystem-for-linux-september-2023-update/) recently where it comes with `Sparse VHD`, a feature that automatically shrinks the WSL virtual hard disk (VHD) as you use it. If you are already using the latest version of WSL (currently in pre-release as of writing), then you can run the following command to enable it.

```bash
# wsl --manage <distro> --set-sparse <true/false>
wsl --manage Ubuntu --set-sparse true
```

# References

* [https://learn.microsoft.com/en-us/powershell/module/hyper-v/optimize-vhd?view=windowsserver2022-ps](https://learn.microsoft.com/en-us/powershell/module/hyper-v/optimize-vhd?view=windowsserver2022-ps)
    
* [https://www.hanselman.com/blog/shrink-your-wsl2-virtual-disks-and-docker-images-and-reclaim-disk-space](https://www.hanselman.com/blog/shrink-your-wsl2-virtual-disks-and-docker-images-and-reclaim-disk-space)