Multi data center design question

We have two multi-node datacenters currently running mysql, we would like to transition to cockroachdb. Only certain tables within the database are replicated between datacenters, the other tables have independent data. The plan is to have 3 nodes in each datacenter running cockroachdb.

The question is if we lose one of the two datacenters, will the remaining datacenter keep running since we only have 3 out of 6 nodes running, which would not provide a quorum? If not is there some alternate design that can accomplish this?

These are private datacenters and it is not possible to move to a hosted solution.

You could add a 7th node in a public cloud like AWS. Put it in its own region, and configure the default replication zone to prohibit that region. Then it will exist purely as a voter for quorum purposes, and not store any data.

Of course, if one of the data centres becomes fully isolated (both from the other data centre and from the public cloud) then that data centre will not be able to do any processing. That’s probably what you want anyway.

What if it is not possible to have a node in the public cloud at all?