Relocating OneNote’s Cache from an SSD to External Storage on a Tablet

This article describes how to overcome Microsoft's restriction and move OneNote's cache to an external storage device.  You should understand the risks before you follow these procedures. Since my OneNote notebooks are stored on a network storage server and are backed up each evening, I am willing to accept the risk-vs-functionality tradeoffs.

Microsoft's OneNote product on a tablet PC is a fantastic way to share documents, record interviews and take notes.  But my Windows 8 tablet's built-in 64GB solid-state drive is too small for all of my applications and OneNote's cache. Moving the cache to an external micro SD card is not as simple as it should be. Microsoft intentionally prevents moving the OneNote cache to an external device, but this restriction is problematic for a Tablet PC.

Attempting to change this setting in the File -> Options -> Save & Backup settings shows the following warning:

For my Tablet PC, the external microSD card will always be inserted in the computer. Let's move the cache anyway.

Mklink: Symbolic Links for Windows

The Mklink command allows us to create a symbolic link from one location to a new directory on the external microSD card.  For example, let's create a "directory junction" link in the C:\ drive:

The above command creates a link from the internal C: drive directory to the external microSD directory. The C: drive directory can now be used as the OneNote location for files and cache.  The operating system will place these files on the microSD card without OneNote complaining.

Other Notes

Microsoft's OneNote will periodically flush files from its cache.  This is good, but does not work consistently.  When OneNote's cache is on the Windows 8 system folder, I notice free space gradually decrease over time.  I like the system folder to hold Windows 8 only and move all temporary and cache files to other disks.

Placing cache files on a removable device will cause problems if that device is absent when OneNote starts.