iTunes app on two different computer to same media library?

I can't answer all your questions but I see a problem. A key part is the library file which is a single file. If iTunes on one computer has it open (and when it is open iTunes constantly changes it with playcount updates, etc.) your second computer will not also be able to open the file. You'd probably get a message about the file already being open in another application.

You could create two library files, one on each computer, but then you'd have to keep them independently up to date. They can share the same media.

If they are saying the play counts etc. are stored on each computer then we are talking about each computer having its own set of library files. iTunes works with two main sets of files. One set is the all your media files. The other one is the main library file (iTunes Library.itl) which tells the application what music you have in your collection, where the files are located, playlists, metadata like albums and artist which exist in both the files and in the library file, and metadata such as playcount which is only present in the library file.

All those other files in your list are part of the library file structure, but the critical one is iTunes Library.itl.

I mentioned having two library files as an option, but then you have to maintain each one. If you add a new file to one computer but forget to do so on the other then the file will be present on your media drive but it will not appear in library 2. Likewise, if you create a playlist in one library you will have to do it on the otehr ocmputer too (presuming you want the same library content and structure on each computer).

I believe that if I am told the file is in use and I can not access the file, that would be ok.

Sure, but then you cannot have two users working with the library simultaneously. You need to be very scenario specific when asking questions here as major decisions can be based upon small details. If you are one person using two computers then you can shut down iTunes when you move to another computer. If there's multiple users trying to use the library at the same time then I strongly suspect you will get the error message.

It sounded to me like you wanted just a single library file which would work but only if only one iTunes is running at any one time.

First, do you know what is in the iTunes Library.xml file approximately?

What are the iTunes library files? - http://support.apple.com/kb/HT1660

More on iTunes library files and what they do - http://en.wikipedia.org/wiki/ITunes#Media_management

What are all those iTunes files? - http://www.macworld.com/article/139974/2009/04/itunes_files.html

Where are my iTunes files located? - http://support.apple.com/kb/ht1391

The .xml file is a mostly but not completely identical library file in a format readable to applications that can use .xml You could open it in a text editor if you wished and it would be somewhat understandable. The .itl file can only be read by iTunes.

I had defaulted to the single library model because I figured that was the only way it would work, but it sounds like I could have two different library files on separate machines, but they point to a single media library. Does that mean two different computers access the same media at the same time (a very unlikely scenario on my part, but just curious)

Yes, the two library files would point to the same media collection. I believe a media file could be played by two computers at the same time (but don't have a setup to try it) because it isn't really being opened by an application for editing, just read. Perhaps if both people got info on a file at the same time and both were trying to change the metadata such as track name at the same time it might present problems because then the file is open for editing.

Two library file option

So how does one go about configuring each machines unique library to point to the single media library residing on the NAS?

I have zero experience with NAS but I believe it is just like having an external drive. You would need to relocate your media to the NAS using the links below. Now you have your library files (the .itl, .xml, a few other organizational files and folders) on an internal and the media files on the NAS. I am not sure at this stage but in moving the media it may have left the files on the internal drive so you'd want to get rid of those media folders since they are no longer being used. Now copy the trimmed iTunes folder from one computer to the other. At this stage the iTunes folder should just be library files (I avoid calling a media collection a media "library" since this is confusing in iTunes; the library is the library file). When you start iTunes on the second computer the library is already configured from the first computer to look for the media files on the NAS.

iTunes 11 for Mac: Change where your iTunes files are stored - http://support.apple.com/kb/PH12165 - more information at: https://discussions.apple.com/thread/5036221?answerId=22026652022#22026652022

Note when using NAS. The NAS must be up and active before starting iTunes or iTunes will not be able to find your files and will give you a bunch of broken links. Nor will it start looking for them again when you turn on the NAS except one by one as you try to play them and it suddenly finds that particular file is there after all. iTunes has a quick look for the files as you start it and won't look again until you try to either edit or play a file. To get rid of hte broken links in bulk you will have to quit iTunes, wake the NAS, then start iTunes again (or use a script that is horribly slow if we're talking telling iTunes to re-check file links for a whole library).

I understand that in this scenario, in the event that one computer downloads some music, the second computer will not know about it. I assume that the second computer will see that the music was downloaded and I will be able to added the music to the second computer (but does this add a second file of the music or just a link the copy that resides in the media folder?)

Again I don't have hands-on experience with this. I can only say what I think might happen and if you find something isn't working as we thought then we'll have to modify methods. I am presuming you are leaving your preferences set to default. iTunes will now be storing media on the NAS but organized as it would as if it was on the internal. When you add media on one computer it will place the media in the correct folder. If you go to that folder from computer 2 and drag it to an iTunes window it may just see there is already a file in the correct location and you're fine with no duplicate. If it places a second copy in the folder then there may be ways to get around this, perhaps by holding down the option key while dragging the file which normally tells iTunes to add an item to the library but use the file where it is currently located (which in your case would be okay since it is located in the right place already).

I would think this would work for movies too. I have zero movies in my iTunes library so again I can't speak from experience.

If you do this you might wish to check the Dougscripts web site. It will require diligence on your part to keep both libraries up to date. I recall there is a script you can run which will browse a folder you select and add files to your library that are in the folder that are not already in the library. I don't know if it will work down folder levels which is what you would really need, or it just looks at one level in the folder and not search a while library folder and subfolders.

My experience has been different versions of iTunes will not play nicely with a shared library. The easy solution is to have iTunes running on one computer (for fun, we'll call it your master or server). Turn on Sharing in that iTunes preferences. On the second computer (slave or workstation), it's copy of iTunes would simply access the shared library from the master, with the option to update play counts.

Yes, I know the OP noted they 'can' share, but from their post, they seem unaware that everything can be shared. Music, Videos, pictures via iPhoto sharing. It's all there.

Again no experience with either app.

Yes, as I suspected, iTunes will of course open the library from any computer but you can only have it open by one at a time. You don't have that issue where each computer has its own library file but then you have all the updating issues unless you don't care about that (for example where each computer is used by a different person with their own music tastes and you just share media).

Another point as Paul Vail observed, each computer must have the same version of iTunes. No running iTunes 10 on one and iTunes 11 on another (but I'm guessing that is not the case from your report that the library would open from both computers).

Um, no. the other two programs are editors, not intended as servers. iTunes (and iPhoto) were engineered to share as an option. Your tunes and movies are stored in iTunes libraries. As mentioned before, you can share from one iTunes to others (or iOS devices such as AppleTV/ipod/ipad/iphone). The shared content is accessed from within the appropriate apps on the other devices -- not pointing those apps or applicatioins to the folder containing your library, but rather handshaking with the iTunes (or iPhoto) running on the server/master machine.

Edit your content in FCP, export the final product, import that into iTunes and enjoy. I would NOT recommend having iTunes on each computer on the network accessing a centralized sharepoint such as your NAS independently. The support files in the iTunes library will be at risk.

In case anyone finds this thread, I'll add a bit about my recent experience with sharing an iTunes library between multiple Macs by storing the iTunes files and media on a Synology NAS.

1. I set up my Synology NAS, which is pretty simple to do.
2. Copied over my whole iTunes library over to the NAS
3. I set up all my Macs to automount the NAS using the instructions here:http://useyourloaf.com/blog/2011/01/24/using-the-mac-os-x-automounter.html
4. Now, I did the option-click startup of iTunes to choose which library to use. I browsed to the automount that I set up in step 3 and found my way to the iTunes Library.xml on the NAS

Step 3 is the hardest part if you're not familiar with setting up automounts. I'm now pretty familiar with the process. 🙂

I set this up yesterday on two different Macs. I have one iMac with iTunes running all the time since it acts as the hub for our Apple TVs. I have a MacBook Air that is also connected from which I basically just play music while I work.

So far I have not seen any problems, though as I said, I've only been running this since last night. I tried to see if play counts and ratings would update on the iMac as I played songs from the MacBook Air, but that does not happen. I suspect that those types of changes will not be reflected on the iMac until I restart iTunes on the iMac. For me, that's not a big deal since, again, the iMac is basically just running iTunes to share its content with Apple TVs.

I'll post an update if anything terrible or unexpected happens.

After playing around a bit, I have found that whichever computer opens iTunes first will stay in charge of writing to the iTunes Library.xml file until it quits. So if I open iTunes on my iMac first, and then open iTunes on my Air, any activity on my Air is completely ignored. That includes play counts and ratings, but more importantly it includes adding or deleting items from the library.

So if I decide to rip some new music or download music from the iTunes Store on a Mac that did not open the iTunes library first, then none of those changes will be saved. When I quit and restart iTunes, it will not show that new music. The music itself is of course there on the NAS, but the library XML doesn't have a record of it.

So just a word of warning to anyone who wants to share an iTunes library on a NAS and expects to be able to do significant manipulation of the library from all computers. It will likely get messy unless you decide on one computer acting as the "master" and always make sure that its the first to start up iTunes.

For my particular situation, this works fine. For others, it may not.

Alex Kim wrote:

So just a word of warning to anyone who wants to share an iTunes library on a NAS and expects to be able to do significant manipulation of the library from all computers. It will likely get messy unless you decide on one computer acting as the "master" and always make sure that its the first to start up iTunes.

To go back a bit earlier, it works fine if you have one iTunes folder on the NAS and every computer uses that one iTunes folder.

Only one compuer can open the iTunes library at a time.

When you open iTunes and any computer, all changes will be refelcte on all othere computers (when you open iTunes on those computers.

The issue comes if the iTunes library.itl file is on each computer. Changes are not reflected on other computers.

The music itself is of course there on the NAS, but the library XML doesn't have a record of it.

iTunes does not care about the iTunes library.xml file. It is created only so other apps can access iTunes.

Yeah, I made a mistake in my previous posts. Anywhere I wrote "iTunes library.xml" I actually meant to write "iTunes library.itl". I copy/pasted the text from earlier in the thread and wasn't paying close enough attention to what I grabbed.

To go back a bit earlier, it works fine if you have one iTunes folder on the NAS and every computer uses that one iTunes folder.

Only one compuer can open the iTunes library at a time.

I guess this is the part that wasn't clear to me before trying things out myself. I find that any number of computers can open the iTunes library at a time, but only the first one will actually be able to modify it. If you just want to play what's in the library, it works fine (for me so far).

I guess this is the part that wasn't clear to me before trying things out myself. I find that any number of computers can open the iTunes library at a time, but only the first one will actually be able to modify it. If you just want to play what's in the library, it works fine (for me so far).

So each computer at the same time, is using the same iTunes library.itl stored on the NAS?

And it can be opened multiple times (using the iTunes Server on the NAS)?

iTunes library = iTunes folder (with iTunes library.itl, etc. and all iTunes media, regardless of where it is located).

iTunes media folder = By default, contains the media in iTunes and by default is located inside the iTunes folder.