Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 420 discussion

A - multi-az instance : failover takes between 60-120 sec D - multi-az cluster: failover around 35 sec

The correct answer is: D. Use an Amazon RDS Multi-AZ DB cluster deployment. Point the read workload to the reader endpoint. Explanation: The company wants high availability, automatic failover support in less than 40 seconds, read offloading from the primary instance, and cost-effectiveness. Answer D is the best choice for several reasons: 1. Amazon RDS Multi-AZ deployments provide high availability and automatic failover support. 2. In a Multi-AZ DB cluster, Amazon RDS automatically provisions and maintains a standby in a different Availability Zone. If a failure occurs, Amazon RDS performs an automatic failover to the standby, minimizing downtime. 3. The "Reader endpoint" for an Amazon RDS DB cluster provides load-balancing support for read-only connections to the DB cluster. Directing read traffic to the reader endpoint helps in offloading read operations from the primary instance.

to offload read we use read replicas also there is no such thing as reader endpoint in rds, it is only on aurora

https://aws.amazon.com/rds/features/multi-az/ Amazon RDS Multi-AZ with two readable standbys

I think the cluster is over-kill - but the company 'wants to use an Amazon RDS ... DB cluster'.

A would be cheapest but "failover times are typically 60–120 seconds" which does not meet our requirements. We need Multi-AZ DB cluster (not instance). This has a reader endpoint by default, thus no need for additional read replicas (to "keep costs as low as possible"). https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.MultiAZSingleStandby.html

in question, it has mentioned that "keep costs as low as possible" In a Multi-AZ configuration, the DB instances and EBS storage volumes are deployed across two Availability Zones. It provides high availability and failover support for DB instances. This setup is primarily for disaster recovery. It involves a primary DB instance and a standby replica, which is a copy of the primary DB instance. The standby replica is not accessible directly; instead, it serves as a failover target in case the primary instance fails.

It is D. A is not correct. Multi-AZ DB instance deployment, which creates a primary instance and a standby instance to provide failover support. However, the standby instance does not serve traffic.

https://aws.amazon.com/blogs/database/choose-the-right-amazon-rds-deployment-option-single-az-instance-multi-az-instance-or-multi-az-database-cluster/#:~:text=Unlike%20Multi%2DAZ%20instance%20deployment,different%20AZs%20serving%20read%20traffic. According to this the answer is D "Unlike Multi-AZ instance deployment, where the secondary instance can’t be accessed for read or writes, Multi-AZ DB cluster deployment consists of primary instance running in one AZ serving read-write traffic and two other standby running in two different AZs serving read traffic." You don't have to create read replicas with cluster deployment so B is out.

D Fail-over on Multi-AZ DB instance is 60-120s On Cluster, the time under 35s

D. Use an Amazon RDS Multi-AZ DB cluster deployment. Point the read workload to the reader endpoint

Use an Amazon RDS Multi-AZ DB cluster deployment Point the read workload to the reader endpoint.

The solutions architect should use an Amazon RDS Multi-AZ DB instance deployment. The company can create one read replica and point the read workload to the read replica. Amazon RDS provides high availability and failover support for DB instances using Multi-AZ deployments.

and d.. Multi-AZ DB clusters typically have lower write latency when compared to Multi-AZ DB instance deployments. They also allow read-only workloads to run on reader DB instances.

This is as case where both option A and D can work, but option D gives 2 DB instances for read compared to only 1 given by option A. Costwise they are the same as both options use 3 DB instances.

lowest cost option, and effective with read replica

It's D. Read well: "A company wants to use an Amazon RDS for PostgreSQL DB CLUSTER".