We are trying to expand our reliability setup using VPC in us-west-1. The 'a' and 'b' AZs work fine, but when I try to create subnets on 'c' it just fails with the message:
Value (us-west-1c) for parameter availabilityZone is invalid. Subnets can currently only be created in the following availability zones: us-west-1b, us-west-1a.
Is this a transient failure or are there just only two VPC-enabled AZs in that region? If the latter, is there a list somewhere with how many AZs in each region are VPC-enabled?