Amazon RDS Multi-AZ Deployments: Readable Standby Instances

TABLE OF CONTENT
1. Introduction2. Architecture of a Multi-AZ DB Cluster Multi-AZ DB Cluster Advantages4. Multi-AZ Deployments vs. Multi-AZ Replicas5. Read Replicas Vs. Readable Standby Instances6. Different pricing7. Multi-AZ DB Cluster Availability8. Conclusion9. CloudThat 10. FAQs 1. Introduction:
Amazon RDS makes it easy to set up, operate, and scale a relational database in cloud. It provides scalable capacity at a low price while automating time-consuming administrative tasks such as database setup, patching, backups, and hardware provisioning. Amazon RDS now supports multiAZ deployments with readable standby instances. It’s also known as Multi-AZ DB Cluster deployments and is currently in preview. Multi-AZ DB Cluster deployments with two readable DB instances can provide additional read capacity for Amazon RDS Multi-AZ deployment. This will also serve to meet critical transaction latency requirements for workloads.
2. Architecture for Multi-AZ DB Cluster Architecture
Amazon RDS uses the DB Engine’s native replication features in order to replicate data from the writer DB example to reader DB instances within a Multi-AZ DB Cluster. Reader DB instances are updated whenever a writer DB instance makes a change. To be applied and committed, a change must be acknowledged by at minimum one reader database instance. Reader DBs serve as failover targets and read traffic to increase application throughput.

Source: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/multi-az-db-clusters-concepts.html
3. Multi-AZ DB Cluster Advantages
Amazon RDS MultiAZ deployments are suitable for production database workloads. Data is replicated synchronously to a standby instance located in a different Availability Zone. Each Availability Zone is designed to be extremely reliable and runs on its own, physically distinct infrastructure. Amazon RDS automatically switches to standby when there is an infrastructure failure. This allows your applications to resume database operations once the loss has passed. This new method eliminates one of the limitations of standard RDS multiAZ deployments: the inability of the synchronously replicated standby instance to accept connections. Amazon RDS’ revised Topology of MultiAZ Cluster deployments will benefit database applications that require increased read capacity and consistent transaction delays. This will increase performance and availability. Amazon RDS automatically configures data replica for one primary and two readable standing DB instances across three Availability zones using the new Multi-AZ DB deployment option. The standby DB instances can be used as failover targets and read traffic to increase throughput without the need to attach more read replica DB instance instances.
4. Multi-AZ Read Replicas vs. MultiAZ Deployments
5. Read Replicas Vs. Readable Standby Instances
6. Price differences
The db.m6gd.large option is the most affordable, with two readable standby instances. However, it costs 0.522 USD an hour on-demand. This is significantly more expensive than a standard multiAZ deployment. A comparable db.m6g.large instance costs 0.304 USD an hour, but there are cheaper instances.7 Multi-AZ DB Cluster Availability Only the following AWS Regions offer Multi-AZ deployments with readable standingby instances. :
US East (N. Virginia)
US West (Oregon)
Europe (Ireland).
8. Conclusion
After a thorough discussion, we can now conclude that AWS MultiAZ DB cluster with readable standing instances can be used for workloads where more read scalability is required and severe transaction latency is required, while provisioning highly-available and durable applications.
9. CloudThat
CloudThat is AWS (Amazon Web Services), a pioneer in Cloud consulting.