Here are some topics I learned during my last IBM Connections upgrade project from vesion 3.0.1 to 4.5.
Upgrading my Virtualbox server to Ubuntu 9.10
I have a Ubuntu-based server where I do host several Virtualbox images for test and demo purposes. This server was still running on Ubuntu 9.04 and EXT3 as file system. Although I do not have too much experience with Linux