This is a somewhat complicated issue; I've always run my iTunes Music Files from an external hard drive because I have an extensive music library (more then 1 TB). As my library has grown so have the number of iMac's and MacBooks in my office studio. I purchased a Drobo 5N NAS box and decided that since I work at different computers doing different tasks at different times, copying my ext h/d iTunes music files and library file to the NAS, all computers regardless of which one I was working from could play music. I setup the music library the same way on my NAS as it was on my ext h/d identical to the way it is setup on my MacBook h/d, (Music/iTunes/iTunes Media/Music). When I tried playing music from my MacBook with iTunes pointing to the *.itl file on the NAS, the music started skipping intermittently. Disappointed ( didn't allow for the NAS time to optimize, my fault). I moved my library back to my external drive off of one of my MacBook's. I rebuilt the *.itl file all over again. But what happened, with the NAS turned off, when I brought up iTunes, iTunes would open up a dialogue box stating the NAS was not mounted. I would close the dialog box and search for an album, and try to play it and get another dialog box saying file not found. After looking at my MacBook h/d and my external h/d, I realized that the *.itl file on my ext h/d was in kb and the *.itl file on my MacBook h/d was in MB. In other words, altho I pointed iTunes to my iTunes Media folder on my ext h/d, it was updating the *.itl file on my MacBook's iTunes Media Folder instead and this was the current iTunes Library File. To add to my own nemesis, I continued seeing a lot of duplicate music files. I use TuneUp as a support utility to keep my library clean and ran the "find duplicates" function. Lucky for me, it archives all duplicate files to a specified folder. When the utility finished running I continued to see duplicate music files and files not found in many albums so I did a CMD + I on the files and realized that it was looking at files in my ext h/d and in the NAS. Keep in mind that my NAS has been turned off all the time during this entire exercise. So 2 problems occurred. First I thought the *.itl file on my ext h/d was the current library db when it was the one on my MacBook that was being updated. So was I suppose to be pointing iTunes to the ext h/d *.itl file and not the iTunes Media folder? And second; I some how combined the the *.itl db on the NAS with the one on my MacBook *.itl drive and need to fix this. With all this explained, my problem is how to I go about fixing my iTunes Library (itl) file. And could I follow the initial concept of running my iTunes library from the Drobo NAS?