As I mentioned in an earlier post about backing up a Zune Library (Backup a Zune Library...), I wanted to find a way to be able to actually store the Zune library database on a different drive.  I played with the Microsoft Sysinternals “Junction” tool, which lets you create hardlinks (Wikipedia on Hardlinks) and managed to get it to work.  Here’s the process to do it yourself.  Replace UserName with your Windows user name and D:\Music\Zune\Library with the path to the folder you want to store the database in.

1. Download Junction.exe from here: http://technet.microsoft.com/en-us/sysinternals/bb896768.aspx (replace D:\Utils\Sysinternals\junction.exe below with the path you downloaded junction.exe to)
2. Shut down the Zune software if it is running.
3. Rename the folder C:\Users\UserName\AppData\Local\Microsoft\Zune to Zune_backup (just to be safe).  You may encounter a file locking issue, but I found that if I waited a few minutes it worked.
4. Copy the Zune_backup folder to D:\Music\Zune and rename it to Library
5. Run the following command:

   D:\Utils\Sysinternals\junction.exe Zune D:\Music\Zune\Library

That should do it!  Start Zune up again and your library should be up and running.  Now you should be able to reinstall the OS without having to back up the Zune library.  I might try to whip up a PowerShell or Batch file to do this, but don’t get too hopeful :).