What is the difference between Database Mirroring and Database Replication such as Multi A-Z deployment in Amazon RDS?

Question

I have an application database running with MySQL engine on Amazon RDS. For better availability of our data for users in all parts of the world I'm looking for the best solution.

In the previous version of the application, we mirrored our database in US and Singapore, so that users got a better performance in terms of speed and on our side, we had backup if any disaster occurred.

Now as we moved to Amazon, will having Multi A-Z Deployment serve us in the same way? I mean replicates the database in all regions but will RDS still work in a single region only?

I have done some studies but still not sure so please ask me any further questions if I'm being puzzling.

Thank you.

Answer 1

I think you need both the Multi-AZ and the Read Replica features of AWS RDS.

Multi-AZ just creates a non-accessible secondary DB in another availability zone and in case the primary fails, AWS would switch over to the secondary DB. So you have failover.

In the case you want to increase the performance, and your application can work in read-only mode in Singapore (for example), the Read Replica would be perfect. If writes are also required, you would need to route them to the primary read-write database.

AWS supports a combination of the two approaches.

Answer 2

RDS MySQL Multi-AZ deployments currently works only inside an Amazon EC2 region. RDS Read replica's also need to be present inside the same Amazon EC2 region. Inter region replication is the most requested feature in AWS RDS to replicate data to another RDS in Alternative Amazon EC2 region. It is in their road map currently.