Are you running PR1.3? I think there is an issue with tracker,it doesn't appear to be able to cope with indexing large amounts of data

I have similar problem with my music collection (around 25GB) only way I can get it onto N9 without Music Player being constantly 'Updating library' is to transfer it to N9 in small groups, maybe 5 albums (no more than 500MB) at a time, otherwise tracker seems to hit a problem and I haven't found a way of recovering tracker when I hit this issue

This didn't happen to me on PR1.2 (although tracker version is 0.10.37 in both firmwares)

See thread http://talk.maemo.org/showthread.php?t=85529 for my report, maybe these two can be merged?