Q: I now have so much music that I am about to start my second external hard drive on my laptop. Can songs from both discs be added to the library and will iTunes automatically select the appropriate drive when playing a selection from both drives?
A: The simplest way to do this is to ensure that you have the “Copy files to iTunes Music Folder when adding to library” option turned OFF in your iTunes advanced preferences:
This will ensure that any tracks that you add to your iTunes library via drag-and-drop or the File, Add to Library menu are simply referenced from their original locations (ie, on whichever external drive they’re located on), rather than being copied into the iTunes Music Folder location. iTunes simply stores the full path to the original location of the file, referencing it from that location, regardless of which hard drive or other device that it is located on.
Keep in mind that when importing tracks in this manner, you will not be able to allow iTunes to manage your music folder structure for you, as it normally expects that all of your music files live in its normal iTunes Music Folder location, and will not manage any tracks outside of this folder path.
Therefore, since iTunes cannot manage the track file/folder organization, you will want to ensure that you have the tracks located in whatever organized directory structure you prefer before importing them into your iTunes library. iTunes stores the absolute path to each file, and it is much more complicated to move files around after they have been imported into iTunes, as it will lose track of their locations (resulting in broken links in your iTunes library).
Further, when deleting tracks from your iTunes library, if they are located outside of the iTunes Music Folder, then iTunes itself will not offer to delete the underlying physical file for you—you will have to find the file and remove it from your hard drive manually. Again, iTunes considers any tracks located outside of its own “iTunes Music Folder” to be outside of its control, and therefore does not manage these files in any way, other than simply referencing them.
If you prefer to use the automatic folder organization and management features of iTunes, you may want to consider purchasing a large enough external hard drive to store your entire music collection, and then simply changing your iTunes Music Folder location to the external drive and storing all of your content on there. This will allow you to take advantage of iTunes’ automatic file/folder management features, where it will keep the music files organized into a proper subdirectory structure, and also handle cleaning up any tracks as you delete them from your library.
If you do plan on changing your music folder path to another drive, the iTunes Consolidate Library function (found under the “Advanced” menu) can be used to migrate all of your music files to the new iTunes Music Folder path.