Multi region architecture with active active mode azure

Question

I have some doubts about implementing a multi-region architecture in azure, I am running my application currently in one region and I am saving some data in blob storage and others in the PostgreSQL database. I wanted to replicate my whole architecture in different regions to be near to other customers. So I will be using Traffic manager to route the traffic based on the source region, but when doing my research about the replica for databases and data storage I find that the replica is in read-only mode. So if want to have active/ active region architecture what should I do exactly?

Answer 1

Building a true active-active architecture with any relational database is tricky, since as you pointed out, all the replicas are read-only. There are a couple of avenues you can pursue:

• Can you switch to Cosmos DB? That would provide a true active-active architecture.
• If you have to stick with Postgres, you could still run your entire app active-active but write queries need to go cross-region. But you can (if you have control of your app code) still make use of local reads.
• If you are willing to rewrite your app quite a bit, while still staying with SQL, you can build an append-only data model with cross-region replicas and UNION'ed views across them (complicated stuff, we are currently building an example architecture for that but will take a bit longer).

You can explore general guidance about Mission-Critical workloads on Azure here. And there is a fully fledged reference implementation for active-active using Cosmos DB: https://github.com/Azure/Mission-Critical-Online