How can I get iTunes Library to stay pointed to my NAS?

I can answer the second part of your question. Since you just updated the MacBook's iTunes settings to point to the NAS, it's iTunes library file still resides on the MacBook. This is a .itl file in your ~/Music/iTunes folder.

iTunes relies on this database to tell it what's in the media folder. If you add stuff to the media folder without adding it through iTunes (i.e. just dropping files in Finder, or using another copy of iTunes on another machine) then that .itl database does not get updated.

So when you add files through iTunes on your Mac Pro, it updates the .itl database on your Mac Pro, but not your MacBook, so the MB can't see those files. If you add anything through iTunes on the MB, the Mac Pro database won't have it, since the copy of iTunes that connects to that database did not process the files.

I have a similar setup to what you're doing: iTunes media on an external drive connected to my iMac, and a MacBook which I use ONLY Home Sharing on.

You might get the idea to move one .itl file to the NAS and open it in iTunes on both machines, and this will work, but you can/should never have it open in both at the same time. That .itl file is really just an SQLite database, and they don't allow simultaneous access, so I've never even attempted this.

With respect to your first question, check ~/Music/iTunes and see if there are any old library (.itl) files. It's most likely that iTunes is opening an old copy or a backup of the database. If you duplicated the database or started a new one before moving your media, this might be the cause.

Start iTunes and make sure the media folder is set correctly or make some other change in iTunes. Now go to ~/Music/iTunes and look for the .itl file that has most recently been modified. Move all the others out of the folder.

Quit iTunes and restart it while holding the Option/Alt key. This will bring up a dialog that lets you select which database to use. Select the .itl file you left alone and it will continue using that as the default library.

This question was from 2011, so you may have figured out what is causing issue one by now, but here is what I have found, as I have a very similar setup to yours.

If you open iTunes when the you are not mounted to the music volume on your NAS, the tendency is for iTunes to default the iTunes Media location setting that you set in Preferences>Advanced back to the local music library.

Then, even if you are connect to the NAS at a later time but don't realize the reset of the iTunes Media location has taken place, any downloads you do, App updates, music, movies, etc., gets add to the local media folder.

If you change the iTunes Media back to the NAS, then you can go to iTunes and control + click the asset and select show in finder. Then you just drag it to the NAS location and move it there and iTunes Library should reset it's pointer to the file.

The ways that I have tried to prevent this from happening have been to set my NAS Music volume to open at startup automatically and the try and not plug my iPhone into my MBP when I am away from my home network. If you don't open iTunes while the computer is not connected to the NAS, then it will not know that it is missing and will not reset where iTunes Media is stored.

If you want to use iTunes when you are on the road, then save some of your assets to the local music folder, and then remember to reset the preferences when you get home.

The default library is /users/yourname/music/itunes. Just go to that folder and press Command+I. Then you can do either one of the following. You could do both but you don't have to.

• At the top of the File Info dialog box, in the General section, check the box labeled "Locked." A lock will appear on the folder.
• At the bottom of the File Info dialog box under Sharing and Permissions, make all three settings "read only."

After you do that, iTunes can no longer create a library in the default location. If it tries to revert, it will prompt you for the location of the library. That's annoying, but it is much, much better. You don't end up with media files scattered.

If you have files in both places, copy the files from the internal library into the external library into the corresponding folders, then Open them with iTunes to add them to the library.

This is one of those things, like duplicate files, that is not a bug, annoys the crap out of people, but doesn't cause customers to go away. So Apple will never fix it.