Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 539 discussion

Backup & Restore (RPO in hours, RTO in 24 hours or less) Pilot Light (RPO in minutes, RTO in hours) Warm Standby (RPO in seconds, RTO in minutes) *** Right Answer *** Active-Active (RPO is none or possibly seconds, RTO in seconds)

Not A - too expensive and not using AWS services Not B - "RDS for SQL Server" does not support everything that "SQL Server Standard which runs on a VM" does; CDC supports even less (https://docs.aws.amazon.com/dms/latest/userguide/CHAP_Source.SQLServer.html). Also it would be more expensive than C. Not D - "Every night" would not meet the RPO requirement

AWS Elastic Disaster Recovery (AWS DRS): A service that can replicate entire virtual machines, including your SQL Server instance, to a secondary region for disaster recovery

AWS DMS with CDC can replicate changes from the on-premises SQL Server to the RDS instance in near real-time, meeting the 30-second RPO requirement. A warm standby RDS instance ensures a faster recovery, meeting the 60-minute RTO requirement. This solution is more cost-effective than upgrading to SQL Server Enterprise and provides a managed, scalable database service.

IMO answer is B. AWS Elastic Disaster Recovery is cheaper and may meet the RTO/RPO requirements of the question, but option C states that it is configured as a pilot light (RTO/RPO 10s minute)

RPO: the maximum acceptable amount of *data loss* during an outage or disaster. RTO: the maximum acceptable amount of *downtime* after a failure. Why B (RDS with DMS) might be better: 1. RTO Guarantee: A warm standby database provides faster recovery since the database is preconfigured and ready to accept traffic. 2. Simplicity: For workloads compatible with RDS and DMS, this approach simplifies management. Why C (Elastic DR) might be better: 1. Workload Compatibility: If the on-premises SQL Server workload uses features that RDS or DMS cannot support, Elastic DR ensures full replication by mirroring the entire VM or disk. 2. Cost: Elastic DR replicates data but does not run a live database, making it much cheaper than a warm standby RDS. "The DR solution needs to minimize costs wherever possible" - That makes me think C is the answer.

Pilot light (RPO in minutes, RTO in tens of minutes) Warm standby (RPO in seconds, RTO in minutes) https://docs.aws.amazon.com/wellarchitected/latest/reliability-pillar/rel_planning_for_recovery_disaster_recovery.html

AWS DRS(AWS Elastic Disaster Recovery) enables RPOs of seconds and RTOs of minutes.

https://docs.aws.amazon.com/whitepapers/latest/disaster-recovery-workloads-on-aws/disaster-recovery-options-in-the-cloud.html#warm-standby

A: Not possible B: With RDS it means your failover will launch a different database engine. This is wrong in general D: No comments C: It is a disk based replication so it will be similar DB server and this is the product managed by AWS for the DR of on-prem setups. https://aws.amazon.com/blogs/modernizing-with-aws/how-to-set-up-disaster-recovery-for-sql-server-always-on-availability-groups-using-aws-elastic-disaster-recovery/

AWS Elastic Disaster Recovery If you are considering the pilot light or warm standby strategy for disaster recovery, AWS Elastic Disaster Recovery could provide an alternative approach with improved benefits. Elastic Disaster Recovery can offer an RPO and RTO target similar to warm standby, but maintain the low-cost approach of pilot light From <https://docs.aws.amazon.com/wellarchitected/latest/reliability-pillar/rel_planning_for_recovery_disaster_recovery.html>

With the pilot light approach, you replicate your data from one environment to another and provision a copy of your core workload infrastructure, not the fully functional copy of your production environment in a recovery environment.

C: Pilot light - In pilot light, databases are always on, thus minimize RPO (can satisfy the 30s requirement) - Only apps are turn off. But it can satisfy the 60 minutes requirement - Warm standby, of cource, can satisfy all the RPO and RTO requirements, but it is more expensive than pilot light

B(warm standby) is doable, but C (pilot light) is most cost effectively. https://aws.amazon.com/tw/blogs/architecture/disaster-recovery-dr-architecture-on-aws-part-iii-pilot-light-and-warm-standby/

The company wants to improve... so needs something guaranteed to be better than 60 mins RTO

Configure a warm standby Amazon RDS for SQL Server database on AWS. Configure AWS Database Migration Service (AWS DMS) to use change data capture (CDC).

AWS DRS enables RPOs of seconds and RTOs of minutes. Pilot light is also cheaper than warm standby. https://aws.amazon.com/disaster-recovery/