Doesn't Flynn require a minimum of 3 servers? What if I'm only running one?
However, single server configurations are perfectly acceptable for personal clusters.
I would strongly recommend taking a cluster backup when you get it up and running though, since single cluster configurations do not deal well with unexpected power failures.
In a single cluster configuration, anything going wrong can destroy your cluster's capability. Think of it as RAID, the more drives, the more you can do for high availability.