I have the following issue: my SSD is 128 GB and it is filled up now. The main culprit is Windows Installer, with 42 GB of cached .MSI and .MSP files.
- make space on the second HDD
- copy the content of the folder C:\windows\installer in a folder on the second HDD (let’s name it d:\backup\msi)
- create a file junction point using the command mklink /J c:\windows\installer d:\DiskC\Windows\Installer (you have to run this command from an elevated cmd.exe, you need adminstrative privileges to execute it and powershell does not recognize mklink, which is an cmd.exe intrinsic)
- delete the files from the folder c:\windows\installer and delete the folder
- move all files from d:\backup\msi to d:\diskC\Windows\installer
- run an uninstall operation and verify it works fine.
A similar procedure should be run to move the folder c:\program data\package cache (see https://stackoverflow.com/questions/12037723/windows-7-symbolic-link-cannot-create-a-file-when-that-file-already-exists).
It worked for me.