Consolidating your iTunes Library is a one-way operation that lets you clean up your hard disk after you've been using iTunes for a while and have added music files to it that might reside in various places all over your computer's hard disk. When you choose this option, iTunes finds all the music files that have been added to the Library without being moved or copied to the iTunes Music folder, and it copies them to appropriate locations in that folder on the basis of their info tags. After you've consolidated your Library, you can recover disk space by deleting the original copies of your music files outside the iTunes Library. In the future, you can be assured that your iTunes Music folder contains all the music files in your collection (provided that you enable the Copy files to iTunes Music folder when adding to library option in the Preferences window).
Consolidate Your Music Library
Choose Advanced, Consolidate Library. A warning dialog box appears, asking whether you're sure you want to proceed, because this is a one-way operation that you can't undo. Click Consolidate to continue.
iTunes begins copying all the stray files into your iTunes Music folder. This process can take several minutes. When it's done, every song entry in your iTunes Library corresponds to a file that's properly organized in your iTunes Music folder according to its Artist and Album info tags.
The next two steps illustrate a couple of configuration options that can help you keep your iTunes Music folder consolidated in the future.
Choose to Keep Your iTunes Music Folder Organized
Open the iTunes Preferences window. (Choose Edit, Preferences in Windows, or iTunes, Preferences on the Mac.) Click the Advanced tab, and then click the General subtab.
Enable the Keep iTunes Music folder organized check box. With this option enabled, every change that you make to the info tags of a file in iTunes' interface is reflected immediately in the filesiTunes renames and moves the files to match their hierarchy within iTunes. Turn off this option if you don't want iTunes messing around with your files' names.
Note
If you re-enable the Keep iTunes Music folder organized option after you had disabled it, iTunes must perform a check against all the songs in its Library to make sure that all the filenames are accurate. This process can take a long time, and you can interrupt it by clicking Stop. However, it's a good idea to let iTunes finish making everything neat, so be patient.
Choose to Copy Future Imported Files to the iTunes Music Folder
The Copy files to iTunes Music folder when adding to library check box determines exactly what happens when you import a new file or group of files into iTunes' database. If the check box is enabled, iTunes makes a duplicate of each imported file and places it into an appropriate place in the iTunes Music folder, in subfolders based on the Artist and Album info tags. If this option is not enabled, the iTunes database instead points to added music files wherever in the system they happen to be.
If you enable this option, you won't have to run a Consolidate Library process again in the future because all the music you add to iTunes will automatically be copied into your iTunes Music folder.
Click OK to commit your configuration changes.
Delete Superfluous Music Files
After the consolidation is complete, use the Finder or Windows Explorer to locate the original music files that were duplicated into the iTunes Music folder, and throw away these superfluous originals. Deleting the originals lets you recover the (perhaps significant) disk space they consume.