Recently we had a server where the system drive was slowly filling up, and we had a hard time finding out what was causing it. After using TreeSize Free (available here), I was able to find out that the folder C:WINDOWSInstaller was using 6GB of the disk. After a quick search, I found that Windows stores uninstall information in this folder, and sometimes files can exist in here even after the initial program or patch that they were used for is no longer installed on the system, or is an “orphaned” installer. I also found a way to safely remove any of these orphaned files, and it is quite easy.
1. Download and install the Windows Installer Cleanup Utility. Normally this utility is used to uninstall programs, but it can also be used to clean up old installers.
2. cd to C:Program FilesWindows Installer Clean Up and run the command msizap G!
This will remove all orphaned installers and only orphaned installers. Freed up about 5.5GB on my server.