availabilityZones

A list of Availability Zones (AZs) where you specifically want to create DB instances in the DB cluster.

For the first three DB instances that you create, RDS distributes each DB instance to a different AZ that you specify. For additional DB instances that you create, RDS randomly distributes them to the AZs that you specified. For example, if you create a DB cluster with one writer instance and three reader instances, RDS might distribute the writer instance to AZ 1, the first reader instance to AZ 2, the second reader instance to AZ 3, and the third reader instance to either AZ 1, AZ 2, or AZ 3.

For more information, see Availability Zones and High availability for Aurora DB instances in the Amazon Aurora User Guide.

Valid for Cluster Type: Aurora DB clusters only

Constraints:

• Can't specify more than three AZs.