Before you set up a multi-node cluster, decide on whether to deploy multiple availability zones.
Availability zones let you split a multi-node cluster into separate operational zones where cluster services and applications are distributed across zones. Availability zones add redundancy and improve reliability by ensuring that cluster services and applications remain active even if one of the zones becomes unavailable for any reason.
To deploy multiple availability zones, each zone requires a power supply, cooling, and internet connectivity that is independent of the other zones. You can house the different zones within a single location that has been segregated according to these requirements, or you could add geographic redundancy by housing each zone in a different geographic location.
Feature support includes:
Maximum of three zones per cluster.
Minimum of three nodes per zone.
Each zone within a cluster must have the same number of nodes.
Individual cluster nodes can belong to a single zone only.
Minimum cluster size to deploy multiple availability zones is six nodes. This cluster size can provide a two-zone cluster with three nodes in each zone.
The default cluster setting is a single availability zone with all nodes being located within that zone.
Note
Availability zones can be configured only during the initial cluster creation phase. Once the cluster is created, there is no option to reconfigure the number of zones. You must reinstall and recreate the cluster to change the zone configuration. There is also no option to add or remove availability zones after an upgrade or while adding nodes to an existing cluster.Example
The following example illustrates a six-node cluster that is split into two availability zones of three nodes each. Each zone has independent power, cooling, and connectivity.
