The installation guide is pretty clear that one of the downsides of using a Virtual Machine to host Discourse is the potential performance hit. Lots of ram and multiple drives are recommended to help alleviate this. I assume the upsides are mostly that you can build/install a known environment, and that if it goes kerblooey, it doesn’t take other stuff down with it.
Now, I already have an Ubuntu server with hardware RAID drives, Postgres 9.1 and Ruby. Instead of installing a VM on my server, why not just install Discourse on the ‘real’ server?
Or, I have a spare server that isn’t even running right now. It would appear that running on a non-virtual machine means instead of steps 1, 2, 3, 4, and 5, I have just step 3, and that’s it. I’m just not sure what hidden downsides of non-virtuality might be.