Redundancy Zones

Consul Enterprise redundancy zones provide both scaling and resiliency benefits by enabling the deployment of non-voting servers alongside voting servers on a per availability zone basis.

When using redundancy zones, if an operator chooses to deploy Consul across 3 availability zones, they could have 2 (or more) servers (1 voting/1 non-voting) in each zone. In the event that a voting member in an availability zone fails, the redundancy zone configuration would automatically promote the non-voting member to a voting member. In the event that an entire availability zone was lost, a non-voting member in one of the existing availability zones would promote to a voting member, keeping server quorum. This capability functions as a "hot standby" for server nodes while also providing (and expanding) the capabilities of enhanced read scalability by also including recovery capabilities.

For more information, review the HashiCorp Learn tutorial on Redundancy Zones, as well as the documentation for Consul Autopilot.