CentOS is my favorite Linux distribution because it is the closest to RedHat you can find (for a reason). And I like RedHat for the simple reason that it is the most supported Linux distribution for any enterprise applications. I know usually both RedHat and SuSE are supported, but SuSE and I was never a love story and I will save you the history of this little drama for this time.
So, the idea is not to run CentOS in a production environment, unless you really have the heart of a warrior and do not care about being supported by a rock solid editor, but instead to run your OnCommand Core lab on a free OS.
I used a CentOS 6 minimal install for this tutorial.