Backing Up Your iTunes Library to a Different Hard Drive
To copy your entire iTunes library to another hard drive, locate the iTunes folder on your computer. Drag this folder to another hard drive or backup device, and you’re all set. This action copies everything, including the playlists in your library.
The copy operation might take some time if your library is huge. Although you can interrupt the operation anytime, the newly copied library might not be complete. Try to finish the copy operation in one go.
If you restore the backup copy to the same computer that has the same name for its hard drive, the backup copy’s playlists work fine. Playlists are essentially lists of songs in the XML (eXtensible Markup Language) format, with pathnames to the song files. If the hard drive name is different, the pathnames won’t work.
However, you can import the playlists back into iTunes:
Choose File→Library→Import Playlist.
The Import dialog box appears.
Browse for and select the iTunes Media Library.xml file (or iTunes Music Library.xml file for previous versions of iTunes) inside the iTunes folder.
The playlist pathnames realign to the new hard drive.