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Windows Symbolic Link to Map Shared Folder Location to Local Folder

I recently set up a shared folder on my NAS to use as a repos drive. After a lot of work, I managed to get it working in both Windows and WSL, but the performance dropped too much when I moved the repos folder to the NAS. I had to reverse my work, updating the firmware on my NAS, renaming the Windows 'D' drive to an 'R' drive, and running an install.bat script and creating an apt_installs.sh file.

Mapping Shared Folder Location to Local Folder: My Journey to Get My Repos Folder Working on Windows and WSL

By Michael Levin

Tuesday, September 20, 2022

It’s really nice when what I want to do for the public is what I have to do for myself. Starting up the Linux Jupyter service after a Windows restart was the perfect example. I restart my machine from scratch more often than I really have to just to clear my mind. Clear computer, clear mind.

Anyhoo, the next thing is to change my shared data drive on my NAS to a shared repos drive (instead). Oh, a firmware update. ALWAYS do your NAS firmware updates. I owned my NAS for maybe a good 2 full years before I finally set it up and as it turns out I’m happy I didn’t have it on for those 2 years. It was really hostile out there. It still is, but QNAP has stepped up and with such high profile NAS hacking, I can lock things down and harden it right away with no Internet connectivity.

So I’m going to be breaking my “D” drive (for data) on my Windows machines, and switching it to an “R” drive (for repos). And while that’s going on, refresh my memory regarding the mounts.

Mounting a drive across systems is not the same as creating a symbolic link within a system. Symbolic links are easier. There’s fewer moving parts. Mounting may touch heterogeneous systems across weird boundaries, such is the case here. Another difference is that symbolic links don’t need target directories in location while mounted drives do. Think! Does this have any ramifications on the WSL2LXD project? It shouldn’t. Oh wait, what was once just a directory Windows-side becomes the R-drive. Can a shortcut make it look like a directory again? Yes, it looks like subst r: C:\Folder\Example

Okay, on the NAS web interface, change the name and path of the data share to repos. Okay go into Hybrid Backup Sync HBS3 and update the jobs so its backup up the location with the new name. Done. Okay, take a look at what happened to my “D” letter drive. An error occurred while reconnecting D to NAS address. Microsoft Windows Network: The local device name is already in use. This connection has not been restored.

Strange message. Anyway, it turns out that I’m going to keep the actual path of the shared folder on the NAS as /data and just rename it as repos. This has the desired effect without having to move a whole bunch of huge files around.

The command I will be using now is:

subst r: C:\Users\mikle\repos

…except that I have a repos folder there already. Copy its contents into the new location. No, Move the files. I’m going to be deleting them from here anyway. This is big for me, moving my main repos off my local machine and onto the NAS. About 4GB of data which is going to take about 2.5 hours to finish. But it is totally worth it because now any machine I sit down at in my house will be equally up-to-date for journal entries without having to deal with git.

I the meanwhile, I want to get some work done. Specifically it’s stuff that’s going to take graphics capabilities on the Linux side.

Oh, it sped up immensely. Only 6 minutes left.

Still, think! Graphics on Linux-side is really a matter of doing a series of apt installs. I want genuine Chrome OS and not just the Chromium that installs automatically with pyppeteer. And I think I’d like to keep the pyppeteer issues separate from the Chrome issues. So focus on the Chrome install first. And by that I mean focus on getting apt_installs.sh working. 1, 2, 3… 1?

Thought-work. This is something that should happen once, just when the install.bat script is run. It should be preserved though, just in case. And so it should use whatever is in the same folder as install.bat because that’s the only reasonable decision there. It will have access to the entire ~/repos location and so it should move the finished one into ~/repos/temp which is used for other purposes during the install. That way even if you blow away the file you created, there’ll be a residual copy left over.

apt_installs.sh won’t be there for a lot of people doing my process because they’ll have just created a batch file Windows-side the copy/paste way. I’ll make sure they know they can create these files, but most of the time they won’t be there. So I need logic similar to the one that checks for the existence of the repos folder before it creates one, but checking the existence of a file.

Okay, the entire repos folder is moved over to my NAS. I have “R” mapped to \EchidNAS\repos. I made a new empty repos folder in my Windows home folder. And now to mount it from under WSL. Okay, now my WSL instance is ahead of my Windows, haha!

sudo mount -t drvfs '\\EchidNAS\repos' /home/healus/repos

Let’s get a ~/repos folder working in Windows, which in PowerShell would really be a $env:USERPROFILE\repos folder working. Okay, got it working. You need to run PowerShell as Administrator (of course).

New-Item -ItemType SymbolicLink -Path "C:\Users\mikle\repos" -Target "\\EchidNAS\repos"

Ugh, I’m going to have to make good note of this because I’m going to have to do that on all my Windows machines.

And finally do a complete (and true) restart to see if it sticks.

shutdown -f -r -t 10

Oops, my WSL Ubuntu 20.04 lost repos (of course). I mean the folder’s still there, but it’s not the network drive silly. I need to re-mount it:

sudo mount -t drvfs '\\EchidNAS\repos' /home/healus/repos

…and then make it persistent updating the line in my /etc/fstab from:

\\EchidNAS\data /home/healus/repos drvfs defaults 0 0


\\EchidNAS\repos /home/healus/repos drvfs defaults 0 0

And another restart!

After quite a bit of work, I’ve managed to get things pretty much the way it’s supposed to be. That convoluted PowerShell command up there is much more easily accomplished in a COM window with Amin rights using this command:

mklink /d %USERPROFILE%\repos R:

However, there’s a problem here that’s going to be unique to me because my repos directory is a Windows-style symlink to a letter-drive which assigned to an SMB-style network shared location.

Okay, so this is imperfect world stuff. Run the script to ensure that it will work for most people correctly. A repos folder is made in their Windows home and that’s used cross-operating system, and most people can start from there. For me, my repos directory appears to be there because of a Windows-style symbolic link, but the cross-OS stuff won’t work. Instead I’ll have an “empty” repos folder Linux-side like everyone else and I’ll have to do the mount and /etc/fstab edit to get my real repos folder. So be it.

Do a full install now (run the script) and ensure that I do have a blank repos folder so the video demos are solid.

Okay, so it does work solid for everyone else, LOL! They get ~/repos and ~/repos/transfer. But for me, I’m going to have to have to do the following commands logged into WSL but not LXD:

sudo mount -t drvfs '\\EchidNAS\repos' /home/ubuntu/repos
lxc config device add jupyter repos disk source=~/repos path=/home/ubuntu/repos

And then I have to sudo vim /etc/fstab to append this because I can’t echo-append it directly in. I’ll have to investigate that.

\\EchidNAS\repos /home/ubuntu/repos drvfs defaults 0 0

But now that I’ve done those things, I should be able to reboot my system and have my NAS-hosted repos folder there. Try it!


Well I really outsmarted myself there. Moving my repos folder onto the NAS was a complete disaster, but it was for the best. I basically undid all my work and went back to a separate data folder on the NAS (home cloud) and a local repos folder. I’m basically reversing most of the stuff from the last few posts and hoping I can get to sleep early enough to hit the work I urgently need to deliver for work.