[Zope] how to keep stuff out of undo

Hi. We have a product (an mp3 jukebox) that uses the ZODB to store a large data structure of all the albums and track names. Many people are allowed to add/remove albums from the database. The problem is, when they do this the entire data structure is backed up for undo. So, by the end of each day, our ZODB has grown so large we are out of disk space. Is is possible make something presistent but keep it from being backed up when it is changed? Thanks, ^Roman