Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 273 discussion

Note: The difference between pilot light and warm standby can sometimes be difficult to understand. Both include an environment in your DR Region with copies of your primary Region assets. The distinction is that pilot light cannot process requests without additional action taken first, whereas warm standby can handle traffic (at reduced capacity levels) immediately. The pilot light approach requires you to “turn on” servers, possibly deploy additional (non-core) infrastructure, and scale up, whereas warm standby only requires you to scale up (everything is already deployed and running). Use your RTO and RPO needs to help you choose between these approaches. https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-options-in-the-cloud.html

Option A is incorrect because while Amazon Aurora global database is a good solution for disaster recovery, pilot light deployment provides only a minimalistic setup and would require manual intervention to make the DR Region fully operational, which increases the recovery time. Option B is a better choice than Option A as it provides a warm standby deployment, which is an automated and more scalable setup than pilot light deployment. In this setup, the database is replicated to the DR Region, and the standby instance can be brought up quickly in case of a disaster. Option C is incorrect because Multi-AZ DB instances provide high availability, not disaster recovery. Option D is a good choice for high availability, but it does not meet the requirement for DR in a different region with the least possible latency.

B: Warm Standby is better when it comes to LOWEST RTO. https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-options-in-the-cloud.html

"Different Region" rules out C and D ("Multi-AZ" is within a region) "Run at reduced capacity" = warm standby (while "pilot light" means that DR resources are shut down and are started manually in case of failover)

The warm standby approach involves ensuring that there is a scaled down, but fully functional, copy of your production environment in another Region. With the pilot light approach, you replicate your data from one Region to another and provision a copy of your core workload infrastructure. Resources required to support data replication and backup, such as databases and object storage, are always on. Other elements, such as application servers, are loaded with application code and configurations, but are "switched off".

An Amazon Aurora global database with a warm standby deployment provides continuous replication from one AWS Region to another, keeping the DR database up-to-date with minimal latency.

In a Pilot Light scenario, only an EC2 Instance and a DB may be running. In Warm Standby, however, everything is running — in a much smaller capacity. This means the load balancer, gateways, databases, all subnets, and everything else are ready to go on a moment's notice. with reference to below statement Option B is a better choice than Option A. "The remaining infrastructure in the DR Region needs to run at reduced capacity and must be able to scale up if necessary".

should be D.