I'm so close to getting iTunes to allow me to run my entire library off of my Amahi/Fedora Linux NAS. I just can't get it to write files to the library folder now. Downloads and converted files both give me the same error: "Do not have enough permissions". I'm not sure what to do at this point, because I know I've given read/write permissions on the Linux NAS end.
You'd be surprised, from a permissions standpoint. I'd go into Terminal and try running some read/write operations by hand using the same account info iTunes is using. Make sure that works before looking any further.
In terminal it also says I don't have permission: "chmod: changing permissions of /var/hda/files/music/iTunes: Operation not permitted"
Ok, form there I'd go back to the NAS, make sure you know which login(s) you've granted R/W permissions to, and then double-check back on the Mac that you're using the same credentials to mount the remote directory.