Seven managers are in a swarm cluster. Is this how should they be distributed across three datacenters or availability zones? Solution: 3-3-1

A 3-3-1 distribution means that if one of the datacenters with three managers goes offline, the remaining total of four managers barely meets quorum, and any further node loss would compromise cluster availability.

With seven Docker Swarm managers, a Raft quorum requires at least four nodes. A 3-3-1 distribution means if a datacenter with three managers fails, the remaining three managers in the second datacenter plus the single manager in the third datacenter (3+1=4) can barely maintain quorum, and any additional failure would lead to a cluster outage.