I would like to create a dual boot system with CentOS 5.5 (though it doesn't really matter what Linux flavor we are talking about). The idea being that I would be able to upgrade one system and then always be able to fall back to the previous set up in case something is malfunctioning on the upgraded system.
/home, /root and /var should be mounted separately on the system because I would want my users and programs to have access the the data on both systems.
I'm willing to experiment, but it would be great if there is an industry standard how to do this.
The purpose of this is to be able to reverse a system to a state that did boot before or possibly test exotic setups during production time with a possibility to quickly revert to the original state.