Move WSL (Bash on Windows) root filesystem to another hard drive?

Question

I've just upgraded the Windows 10 in my laptop to Redstone 1. So I had a test of the Linux subsystem (aka. WSL, LXSS or Bash on Windows). Basically, everything is fine, but there is a problem that the RootFS of WSL is located in the %LocalAppData% path (e.g. C:\Users\xyz\AppData\Local), which is also the place where my Windows OS located. It consumes a lot of the SSD hard drive space in my laptop and I hope I can move it to my external hard drive.

There is an another problem. Since the other hard drive partitions are mounted as DriveFS, it does not support some Linux filesystem features like chmod, and some of my Linux project build scripts only works in VoIFS, which only located in / and /home.

So I tried to move the whole WSL RootFS to another hard drive. Firstly I've tried to make a NTFS Junction (hard link) for C:\Users\xyz\AppData\Local\lxss. I've uninstalled the WSL completely and run mklink for the RootFS to another hard drive, and when I reinstall the WSL again, it couldn't create the new user, and it reports error with code 0x80070003.

Then I searched around, and I got this: moving Linux filesystem - issue #449. It seems that moving and making hard link for WSL RootFS only works before Windows 10 Build 14388, it does not work in the Windows 10 Build 14393 RTM. The only way is moving the whole %LocalAppData% to the external hard drive, but I cannot do that since I'm a laptop user and I can't bring an external hard drive everywhere!

So I would like to ask that, is there any other ways to move WSL out of my system partition? If I can't do that, can I create an extra VoIFS work directory in some other places and compile my stuff?

Thanks and regards, Jackson

Answer 1

If you are using Windows 10 version 1903 (April 2019 Update) or later, you can try the WSL command line tool with the export and import options. If you are using an older Windows 10 version, you can move the distribution to another drive using lxRunOffline.

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Using the WSL command line tool

In Windows 10 version 1903 (April 2019 Update) or later, you can use the wsl.exe command line tool.

1. Export the distribution. Create a .tar file with the distribution to move using wsl.exe --export

wsl.exe --export <DistributionName> <Tar-FileName>

For instance, to export an Ubuntu distribution, you can use

C:\> wsl.exe --export Ubuntu c:\data\ubuntu.tar

2. Import the distribution into the target folder. Then, you can import the exported distribution into another folder

wsl.exe --import <DistributionName> <Folder-To-Install> <Tar-FileName>

For instance, to import the exported Ubuntu into a new UbuntuCustom distribution, you can use

C:\> wsl.exe --import UbuntuCustom d:\wsl\UbuntuCustom c:\data\ubuntu.tar

NOTE: You may check an script for moving WSL distros that use these commands at https://github.com/pxlrbt/move-wsl

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Using LxRunOffline

In any Windows 10 version, you can move the distribution to another drive using lxRunOffline.

1. Set permissions to the target folder. First, I think you must set some permissions to the folder where the distribution will be moved. You may use icacls <dir> /grant "<user>:(OI)(CI)(F)" to set the proper permissions.

C:\> whoami
test\jaime

C:\> icacls D:\wsl /grant "jaime:(OI)(CI)(F)"

NOTE: In addition to the above permissions, I have activated the long path names in Windows.

2. Move the distribution. Using lxrunoffline move.

C:\wsl> lxrunoffline move -n Ubuntu-18.04 -d d:\wsl\installed\Ubuntu-18.04

You may check the installation folder using

C:\wsl> lxrunoffline get-dir -n Ubuntu-18.04
d:\wsl\installed\Ubuntu-18.04

3. Run the distribution. after moving the distribution, you can run the distribution using wsl or the same lxrunoffline

C:\wsl> lxrunoffline run -n Ubuntu-18.04 -w
user@test:~$ exit
logout

C:\wsl> wsl
user@test:/mnt/c/wsl$ exit
logout