I picked up one of those super-cheap ~$200 Windows 10 netbooks from Best Buy a while back because I wanted something inexpensive to keep at the shop for incidental tasks like programming microcontrollers or burning SD cards for Raspberry Pi. Unfortunately, someone at Microsoft boasted that Windows 10 could be installed on a 32GB storage drive, so manufacturers like Asus put exactly 32GB in their discount netbooks leaving very little space (after updates, usually less than 5GB) to install applications.

Fortunately, Windows 10 comes out of the box with the ability to change the default storage locations for the library folders and installation location for apps installed via the Windows Store. However, I use a lot of applications that aren’t available in the Store and I also require a fair bit of space for screen capture videos when I’m walking through a project, so I’m going to need some extra storage space. At least the little Asus that I selected has a MicroSD card slot so I can just grab a 128GB unit and leave it inserted. Windows treats it like any other removable media, but be warned: the MicroSD read/write speed isn’t anything you’re going to write home about! Applications are going to load more slowly, but in most cases will run just fine from RAM. (Writing that previous sentence gave me weird flashbacks of the 8- and 16-bit eras when we often ran applications directly from a floppy and experienced the associated slowdowns.)

Install Windows Applications To SD Card

In most cases, Windows application installers will offer the option to select the install folder. For these, I just have the folder structure of the C: drive root copied to my MicroSD card, notably the Program Files and Program Files (x86) folders, so I just change the drive letter and everything installs like normal. However, many newer applications take advantage of the Windows User/AppData folder to store local data. One notorious example is Fusion360, which installs to the AppData folder and offers no option to do otherwise! For these exceptions, we’ll need to create a symbolic link from the C: version of the AppData folder to the D: drive location.

Use Symbolic Link To Redirect Folders

First off, using a symbolic link to redirect system folders to another location is generally bad practice because it can expose the machine to symlink attacks, but considering we’ve been backed into a corner by arrogant developers and clueless manufacturers, we’re going to need to pull this trick out of the bag. I wouldn’t use this kind of workaround on any mission critical systems, but it should be just fine for this little auxiliary machine. (Technically, Windows shortcuts are symbolic links, so we’re not doing anything too weird. We’re just forcing Windows to use a different storage location for something it prefers to have on the main storage device). The first step is to create a directory on the D: drive that will hold our AppData (since it’s a hidden folder and I’m the only user, I’ll just put it in D:\AppData). From here, just copy the contents of the AppData directory over to the new location and delete (yes, I said delete) the original.

Create Symbolic Links With Windows Command Line

Windows comes with the mlink command to create symbolic links, but you have to use the Command Line terminal to invoke it. Open an elevated command prompt (one with Admin privileges) by pressing Win + X and selecting the appropriate option from the list. The syntax for the command is as follows:

mlink /switch <link> <target>

So, to make C:\Users\<user>\AppData point to the new location on the D: drive, we’ll invoke the following command:

mlink /D "C:\Users\<user>\AppData" "D:\AppData"

Once the link is created, as far as Windows is concerned, the two locations are the same place. If an application needs to access the folder, it will seamlessly connect to the location on D:. As such, Fusion360 will run without a hitch (although it will load more slowly due to the reduced read/write speed)!

Unfortunately, this trick does not work to upgrade Windows 10 to 11, so this machine will be stuck in the late 2010s forever (or until I decide to install Linux on it…again).