Why AWS RDS service needs two subnets from different AZs
As part of our project we are using AWS RDS PostgreSQL service. While creating RDS service AWS mandated to create two sub-nets from different AZ's (ex: us-west-2a and us-west-2b). But we have only one sub-net. Is there any way to overcome this problem.
RDS is built to be Multi-AZ by design, as the best practice for any production environment must use this approach. This will allow you to be sure that in case of an event in one AZ your database will be able to fail-over to the second one. I know that probably you are trying to deploy just one single RDS instance in a single AZ, but the system requires to configure two subnets, as maybe in the future you want to transform your RDS instance in a Multi-AZ instance, this is the reason why you need always two AZ. Defining Subnets is not a process that have any cost, some times the cost is related to IP address availability, but nothing else. So, i am afraid you will have to setup two subnets in two different AZ.
All this is explained in AWS documentation here: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_VPC.WorkingWithRDSInstanceinaVPC.html
Thanks for the nice explanation. Is there any way I can create RDS service using sub-nets created in the Single AZ.
@AWS-User-8752529 You will need to create the subnets in different AZs.
That seems to be the common pattern for some other resources. Let's say your RDS cluster contains 2 db instances, one for writer and the other for reader. For better availability, they better be located in different zones from each other.
Two subnets attached to any new resources we create that aren't related to our accountasked 4 months ago
Why AWS RDS service needs two subnets from different AZsasked 2 months ago
Migration from Aurora PostgreSQL back to regular RDSAccepted Answerasked 3 years ago
DMS between MySQL RDS in 2 different accountsasked 3 days ago
Missing AZ option when adding a new AWS RDS Aurora MySQL readerasked 8 days ago
Random RDS SQL Server QuestionsAccepted Answerasked 4 years ago
AWS Database Migration ServiceAccepted Answerasked 6 years ago
Amazon RDS for PostgreSQL: Configuration differences with PostgreSQL on EC2Accepted Answerasked 2 years ago
why must an RDS always have two subnetsasked 3 years ago
Server error 500 - Page is currently unavailableasked 2 years ago