• Create a Backup folder on another drive will more free space such as (E:\Backup)
  • Rename the Backup folder in %APPDATA%\Apple Computer\MobileSync\Backup to Backup1
  • Open a command prompt and run: mklink /J %APPDATA%\Apple Computer\MobileSync\Backup E:\Backup
  • Move the contents of %APPDATA%\Apple Computer\MobileSync\Backup1 to E:\Backup

iTunes will address the folder the same as it did the previous folder.