No, it was not Jitsu. Jitsu is based on MiragOS/OCaml, Erlang-on-Xen was also a Xen-based unikernel like MirageOS but was (as you can guess) Erlang specific. I think you can now find it at https://github.com/cloudozer/ling .
"Horizontal scalability achieved through the implementation of a load balancing solution is easy." - makes me giggle and not want to continue reading. If one is still relying on vertical scalability then perhaps therein lies your problem.