Review: High Availability and Resilience of Our WordPress Instances
Explore the concepts of high availability and resilience for WordPress instances deployed on AWS. Learn to evaluate recovery point objectives (RPO) and recovery time objectives (RTO) through scenarios involving instance failures and availability zone outages. This lesson helps you understand how health checks, load balancers, and auto scaling groups contribute to maintaining uptime and quick recovery in case of disaster.
We have introduced different recovery strategies and the terms RPO and RTO. In the following lessons, we'll analyze our deployment regarding these objectives. To do so, we will go through a set of scenarios and evaluate which RPOs and RTOs are achievable to get a better understanding of the resilience of our infrastructure.
In the diagram above, we can see the relation of our WordPress instances with the rest of the infrastructure. But what happens in case of a disaster? Will our blog still be up and running?
Let’s define a set of scenarios to evaluate this question:
Scenario 1: One WordPress instance crashes
Let’s start with the simplest scenario: one of the WordPress instances crashes for an unknown reason. Would our users notice?
We can answer this question by looking at the diagram above. The flow of user ...