Fortunatamente, Apple ha sentito le tue grida: iTunes: esegui il backup della libreria di iTunes copiando su un disco rigido esterno :

Consolidate Library

1. Open iTunes Preferences:
2. Choose iTunes > Preferences.
3. Click Advanced.
4. Make sure the option to "Copy files to iTunes Media folder when adding to library" is selected.
5. Click OK.

Note: After you click OK, iTunes copies any files that are added that weren't already in the iTunes Media folder and places the copies in the folder. The original files are left in their original locations. To save space on your hard disk, you might want to delete the original files after confirming import.

1. Choose File > Library > Organize Library.
2. Select the option to "Consolidate files."

Note: If you recently updated to iTunes 9, you might want to consider selecting the option to "Upgrade to iTunes Media organization." This updates the file organization of your iTunes Media folder.

1. Click OK.

Move to External Drive

1. Quit iTunes.
2. Locate your external hard drive.
3. On the desktop or Finder sidebar.
4. Locate your iTunes folder:
5. By default, the iTunes folder is located in: /Users/username/Music

If the iTunes folder is not in the default location listed above then you can find where the iTunes folder is located by following these instructions:

1. Open your iTunes Preferences:
2. Choose iTunes > Preferences.
3. Click Advanced. The location of your iTunes folder will be listed in iTunes Media folder location box.
4. Drag the iTunes folder to your external hard drive. This can take a while if you have a lot of items.
5. When the transfer is complete, your iTunes Library will have been successfully copied to your external hard drive.

Restoring your iTunes Library

1. Quit iTunes.
2. Locate your external hard drive.
3. On the Desktop or Finder sidebar.
4. Drag the iTunes folder (backed up earlier) from your external hard drive to whatever location you desire on your internal hard drive. It is recommended that you choose the default location for the iTunes folder, which is: /Users/username/Music
5. Open iTunes while holding down the Option key (Mac) or Shift key (Windows).
6. In the resulting dialog, click the Choose Library button.