Be wary of the sample questions that are available when studying for the Solutions Architect Certification. I’ve come across some where the answers were out of date or used to be correct and the others were just made up questions that almost make sense but aren’t worded precisely enough to give a proper answer.

By and large finding the sample questions is helpful, but don’t take all of them as truth and look through the documents to verify the answers.

I made my first trip to the San Francisco AWS Loft and definitely learned a lot. I attended the Continuous Delivery and Continuous Integration Day and was introduced to a lot of the build and deployment strategies involved in cloud applications.

The number of attendees was surprising. The entire loft space was filled with I’m guessing around 100 people. Definitely a great idea on the part of AWS to hold sessions like this. I’m pretty amazed at the size of the ecosystem and I’m sure it’s nothing compared to re:Invent.

RDS Failover

Our reporting engine is likely to point at a Read Replica of our database so we wondered what happens when the instance fails. Do we have to detect the failure? Do we have to manually find a new instance?

Here’s what I found:

The failover mechanism automatically changes the DNS record of the DB instance to point to the standby DB instance. As a result, you will need to re-establish any existing connections to your DB instance.

This seems to imply that while you may need to reconnect, you don’t have to reconfigure the connection. This also seems to be referencing the primary instance, but I would assume it applies to Read Replicas but I would like to verify with an RDS expert.

Cross-Region Read Replicas

One of the questions that came up during my discussion with our data center admins was durability and availability of an RDS instance. I knew about Multi-AZ Read Replicas but Cross-Region was new to me.

With Amazon Relational Database Service (Amazon RDS), you can create a MySQL, PostgreSQL, or MariaDB Read Replica in a different AWS Region than the source DB instance. You create a Read Replica to do the following:

  • Improve your disaster recovery capabilities.
  • Scale read operations into a region closer to your users.
  • Make it easier to migrate from a data center in one region to a data center in another region.

I know that I have a lot to learn about cloud deployment so during a meeting with our internal data center admins I asked what they thought about managing releases with VPC deployments. They kindly explained that since some of the resource we would need would have to have a VPN connection to our data center creating new VPCs wouldn’t be ideal because each VPC would require reconfiguration of the corporate firewall. They suggested exploring deployment via subnets.

This seems to make sense, I think my problem was that I was coming from the thought of building everything out, but the operations people control the VPC so I need to rethink things with that in mind.