GarageBand Magic – too much magic?

I know that the new iLife ’08 GarageBand Magic feature is not a substitute for Band in a Box (or the Windows version), but it would be an easy way to make my (rare) guitar practice sessions more interesting. So, imagine my surprise when I just ended up with a bunch of error messages like this one ‘Audio file “Original Bass#3.caf” not found.’, with the option to skip or to search (which of course does not find anything) …

… and a few minutes of silence in the resulting projects:

So, it looked like a major new feature of GarageBand was not working, therefore it should be fairly easy to find out why and what to do about it by googling for this problem… Wrong, it turns out that almost nobody is having this problem. I found one thread on Apple’s support site with a workaround, but I hate to copy files without understanding why and what the impact would be. I have Apple Care protection for my Mac Pro, so let’s give Apple a call… After 79 minutes on the phone with them, I figured out what’s causing this problem, and then I tried to convince them that it’s indeed a genuine bug in the software. While talking to them, I tried a few things on my system, and slowly developed a theory, and verified it:

My system is setup with the original startup disk that stores all applications, but I added three more disks, which I’m running in a RAID configuration to store all data files. To make this work, I am using links in my home directory to link directories like Movies, Music or Pictures to their actual storage location on the second disk. This works with all applications that make use of these files (e.g. Adobe’s Photoshop Lightroom, iTunes, iPhoto, iMovie – the old one, haven’t tried the new version yet – or iDisk). GarageBand also works, as long as I’m not using the new Magic feature.

Magic GarageBand saves the new project to it’s default location, which is the user’s Music/GarageBand directory. The user has no control over that. While it’s saving the project, it needs to access the .caf files, which contain the instrument tracks. These files are stored in the individual directories in /Library/Application Support/Garage/Band/Magic GarageBand. It looks like it can only find these files if the Music/GarageBand directory is on the same disk as the /Library directory (meaning, the startup disk).

A Unix link (or to be more accurate, a soft link in this case) should be should be transparent to an application. The operating system takes care of opening the files, regardless of how they are referenced. GarageBand seems to be different – it looks like it is using the storage location to generate the path to it’s configuration and data files (potentially by creating a relative path starting from the project directory). I tried to capture what GarageBand does in ktrace, but I was not able to extract anything useful (that’s mainly because this was the first time I ever used ktrace). Both people from Apple support that I talked to had no idea what a Unix link was.

Because all other features of GarageBand work with my setup, I’m labeling this behavior as a bug. So far I don’t have a workaround besides putting my Music directory back on my startup disk, and linking some of the subdirectories (e.g. Pictures and Movies) to my RAID system.

Let’s see if Apple can come up with something (or a fix in the next release).