Yeah, this whole LPAR thing is supposed to make oversubscribing less of an issue, but in practical terms it is comparable to Xen PV without HVM mode (Essentially Vt-i without Vt-d). It's not that it never works, it's just that you have to take severe shortcuts and snowflake kernels to get it to work in the first place (so now you're incompatible with the body of knowledge that is the internet), and then you essentially just do multiproces CPU core sharing, memory sharing with swapping etc... not great.