In the CSA pro course it mentioned that RDS multi-az mysql doesn’t support automatic failover. as far as I know this is incorrect. also the AWS documentation mention it will failover automatically in case of AZ failover.
2 Answers
Hi Nir,
Multi-AZ MySQL definitely supports automatic failover if an AZ fails. However, the lecture talks about mutli-region replication. Promotion of a read replica in another region to a master is not automatic…at least not yet.
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ReadRepl.html
–Scott
Hi Nir – I think what Scott said was correct. In the challenge question: It said the multi-AZ MySQL RDS and app servers are in us-east-2 region and read replica is in us-west-2. So RDS now has (at-least) 2 instances in 2 AZs within us-east-2 and 1 read replica in us-west-2.
Option A: "In case of an AZ failure the database will auto-failover to one of the read replicas"
Auto-failover
Multi-AZ RDS MySQL to standby replica in another AZ – possible
Multi-AZ RDS MySQL + Read replica (another region) – Manually possible – not automatic
RDS Aurora Multi-AZ + Read replica (another region) – possible (https://aws.amazon.com/blogs/aws/new-cross-region-read-replicas-for-amazon-aurora/ & https://aws.amazon.com/blogs/aws/additional-failover-control-for-amazon-aurora/)
The key here is cross region which i as well missed in the question (but it clearly mentioned that 1 read replica is in us-west-2). Please let me know if my understanding is correct.
Hi Scott, please go to challenge 2 in chapter 7. see answer A and hear the explanation at 1:00 saying that only aurora auto failover if an AZ fails. this is not talking about a region failure.