Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 338 discussion

I originally went for D but now I think B is correct. D is active-active cluster so whereas B is active-passive (headless cluster) so it is cheaper than D. https://aws.amazon.com/blogs/database/achieve-cost-effective-multi-region-resiliency-with-amazon-aurora-global-database-headless-clusters/

Answer - A https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraMySQL.Replication.CrossRegion.html ----------------------------------------------------------------------------- Before you begin Before you can create an Aurora MySQL DB cluster that is a cross-Region read replica, you must turn on binary logging on your source Aurora MySQL DB cluster. Cross-region replication for Aurora MySQL uses MySQL binary replication to replay changes on the cross-Region read replica DB cluster.

D is correct Set up an Aurora global database for the DB cluster. When setup is complete, remove the DB instance from the secondary Region. The reason why B us incorrect! Reason it's incorrect: Removing the DB instance from the secondary region would defeat the purpose of having a disaster recovery setup. Without a DB instance in the secondary region, you lose the ability to quickly failover in case of a regional outage, which is critical for DR.

This makes the answer D - "a high-volume software as a service (SaaS) platform."

When you set up an Aurora Global Database, the storage layer (Aurora Storage) is continuously and automatically replicated across Regions — independent of whether you have DB instances (readers/writers) running in the secondary Region. If you remove the DB instance from the secondary Region: The replicated storage remains. No compute (no DB instances) = No cost for compute, only storage costs. BUT: In a real failover event, you must promote the secondary cluster. When you promote, you must first create a new DB instance in the secondary Region from the existing storage. This takes some time (typically a few minutes), because Aurora has to spin up the DB instance.

Answer could be D, as this is DR plan, answer B is ask to remove the DB instance which might not suitable for DR plan….. if you remove it… how to replicate data again? you setup again for next replication ?

Giving the requirement is the DR plan for a high-volume software as a service (SaaS) platform, the RTO and RPO should be small, needs a quick recovery, D(warm standby) is a better choice than A ( cold standby, pilot light)

A - No. Higher cost & higher latency. B - No. A DB instance is mandatory in each Region for the global database to function. C - Removing would make DR incomplete, because the secondary Region cannot process failovers or support read replicas. D - Cost slightly higher, yes, but feasible & cost less than A. Overall, I don't like this question ...

Aurora Global Databases offer a cost-effective way to replicate data to a secondary region for disaster recovery. By removing the secondary DB instance after setup, you only pay for storage and minimal compute resources.

https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-global-database.html#aurora-global-database.advantages

B is more cost-effective however because this is DR so when the region fails => still need a DB to fail over and if setting up a DB from snapshot at the time of failure will be risky => D is the answer

"Achieve cost-effective multi-Region resiliency with Amazon Aurora Global Database headless clusters" is exactly the topic here. "A headless secondary Amazon Aurora database cluster is one without a database instance. This type of configuration can lower expenses for an Aurora global database." https://aws.amazon.com/blogs/database/achieve-cost-effective-multi-region-resiliency-with-amazon-aurora-global-database-headless-clusters/

shd be D i guess .. . Migrating the database to Amazon Aurora MySQL allows for improved replication performance and higher scalability compared to Amazon RDS for MySQL. Aurora Replicas provide faster replication, reducing the replication lag, and Aurora Auto Scaling ensures that there are enough Aurora Replicas to handle the incoming traffic. Additionally, Aurora MySQL native functions can replace the stored procedures, reducing the load on the database and improving performance. Option B is not the best solution since adding an ElastiCache for Redis cluster does not address the replication lag issue, and the cache may not have the most up-to-date information. Additionally, replacing the stored procedures with AWS Lambda functions adds additional complexity and may not improve performance.

Set up an Aurora global database for the DB cluster. Specify a minimum of one DB instance in the secondary Region

should be B for most cost effective solution. see the link - Achieve cost-effective multi-Region resiliency with Amazon Aurora Global Database headless clusters https://aws.amazon.com/blogs/database/achieve-cost-effective-multi-region-resiliency-with-amazon-aurora-global-database-headless-clusters/

MOST cost-effective --> B See section "Creating a headless Aurora DB cluster in a secondary Region" on the link https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Replication.html "Although an Aurora global database requires at least one secondary Aurora DB cluster in a different AWS Region than the primary, you can use a headless configuration for the secondary cluster. A headless secondary Aurora DB cluster is one without a DB instance. This type of configuration can lower expenses for an Aurora global database. In an Aurora DB cluster, compute and storage are decoupled. Without the DB instance, you're not charged for compute, only for storage. If it's set up correctly, a headless secondary's storage volume is kept in-sync with the primary Aurora DB cluster."

D: With Amazon Aurora Global Database, you pay for replicated write I/Os between the primary Region and each secondary Region (in this case 1). Not A because it achieves the same, would be equally costly and adds overhead.