short answer: nope. cockroachdb replicates data for availability and in order to guarantee consistency across the replicas, it uses Raft[1] internally. Raft necessitates a majority of the replicas remain available in order to operate. it ensures that a new 'leader' for each group of replicas is elected if the former leader fails, so that transactions can continue and affected replicas can rejoin their group once they're back online.
raft is premised on overlapping majorities, so to speak. in order to tolerate up to `n` node failures you'd need to run `2n + 1` instances (for nine nodes you'd tolerate up to four node failures).
[1]: https://raft.github.io/raft.pdf