iTunes makes it fairly straightforward to maintain a large library of music, movies, TV shows, podcasts, album art, and other media. It’s easy to keep your iTunes library on an external hard drive (click here to read how to do this). It’s also easy to create multiple, seperate iTunes libraries by holding down the Option key while launching iTunes (click here to read more about how to do this).
It’s less obvious how to split an existing iTunes library, so that some files are stored on one hard drive, while other files are stored on a second hard drive.
By default, when you add a file to iTunes, iTunes copies that file into your iTunes library. This is part of what makes iTunes so easy to use and manage. However, you can prevent iTunes from copying files into its library in by de-selecting Copy files to iTunes Music folder when adding to library in iTunes Preferences. Unfortunately, when I did that in the past, my iTunes media collection quickly became disorganized.
I work around this with a simple keyboard shortcut: I simply hold down the Option key while dragging files into iTunes, making iTunes link to the original file without actually copying it into my iTunes library.
This allows me to store my music, iPhone backups, and podcasts on my MacBook Pro’s hard drive, while I keep all movies and TV shows on an external hard drive. Movies and TV shows take up a lot of megabytes; this helps save space on my MacBook Pro’s hard drive. With the Option-key shortcut described above, iTunes thinks I only have one library while I actually have two.
This does involve a couple of extra steps for movies and TV shows I automatically download from the iTunes store, since I have to move that media to the external drive, and then move it back into iTunes. To do this:
1. In iTunes, find the real location of the media file you want to move by right clicking (or control-clicking) on it and choosing “Show in Finder.”
2. Move this file to your external drive, preferably in a well-named folder such as “iTunes Movies”.
3. After the file has copied over, delete the original file in iTunes.
4. Now drag the file from the external drive into iTunes while holding down the Option key.
You should confirm the file is copied to the external by repeating step one and choosing “Show in Finder”.
From now on, as long as the external drive is connected, you’ll be able to play back the file. You can even sync it to your iPhone or iPod, or stream to Apple TV!