mongodb: how to upgrade db?

Hey I have mongodb which I have used for a long time. It's version is 1.2.2. Now I have new server running centos 5.5. I know how to install mongodb on it. It's version is 1.6.5. I want to know how I can migrate my db files in /var/lib/mongo/ to 1.6.5? It's just dbs and collections, no index files at all. Is there any tools can easily do that for me?

Copy over the original database files to the new server and restart mongod on the new system. It might be necessary to to start mongod with the --upgrade option in order to migrate existing database files to a new database format (has not changed since 1.4 but possibly between 1.2 and 1.6).