Hi I have had experience with OGG, very good, virtually no downtime (in my case was aprox 5 to 10 minutes in several migrations). You dont need as much as preparation as TTS but there are preparations specially migrating from old 9i to latest versions. But you need a lot of $$$ to buy OGG because you have to license both source and target systems. I have a few customers had to use other ways such as TTS because of the license costs, you cannot buy OGG just for migration purposes, if the customer cannot find a use for OGG after the migration then they need to seriously considering if it's worth it. Thanks -- LSC -- //www.freelists.org/webpage/oracle-l