Amazon Aurora Overview for SysOps Exam

Amazon Aurora is a fully managed relational database service that is compatible with MySQL and PostgreSQL. Understanding its features and metrics is essential for the SysOps Administrator exam. Here's a breakdown of key aspects related to Aurora:

Read Replica Priority Tiers

• Aurora allows assigning a priority tier (between 0 and 15) to each Read Replica.
• This priority setting is crucial for controlling failover operations:
  • Highest Priority (Lowest Tier Number): Aurora promotes the Read Replica with the highest priority to be the new primary instance in the event of a failover.
  • Same Priority: If two replicas have the same priority, Aurora promotes the one with the larger size.
  • Same Priority and Size: If replicas have identical priority and size, one is promoted randomly.

Migration from RDS MySQL to Aurora MySQL

• Aurora supports migrating an RDS MySQL snapshot to an Aurora MySQL cluster. This feature facilitates the transition from RDS MySQL to Aurora MySQL, enabling users to leverage Aurora's advanced capabilities.

CloudWatch Metrics for Aurora

Monitoring Aurora with CloudWatch metrics provides insights into database performance and health. Key metrics include:

• AuroraReplicaLag: Measures the lag time in replicating updates from the primary instance to the replicas. It indicates how synchronized the replicas are with the primary instance.
• AuroraReplicaLagMaximum: The maximum replication lag across all instances in the cluster.
• AuroraReplicaLagMinimum: The minimum replication lag across all instances in the cluster.
• High replica lag can lead to eventual consistency issues, affecting user experience. For example, a user might add an item to their cart, and it may not appear upon refreshing due to replication delays.
• DatabaseConnections: Indicates the current number of connections to the database instance.
• InsertLatency: The average duration of insert operations, which can impact the performance of write-heavy applications.

Conclusion

Understanding these aspects of Aurora is crucial for managing AWS database services effectively, especially in a DevOps context where uptime, performance, and reliability are paramount. Monitoring CloudWatch metrics and configuring Read Replica priorities properly can help ensure a smooth and efficient operational environment for Aurora databases.

To connect to an Amazon Aurora DB cluster directly from outside the VPC, the instances in the cluster must meet the following requirements:

1. The DB instance must have a public IP address