Amazon RDS Cross-Region Read Replicas

RDS Cross-Region Read Replicas

  • RDS Cross-Region Read Replicas create an asynchronously replicated read-only DB instance in a secondary AWS Region.
  • Supported for MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server
  • Cross-Region Read Replicas help to improve
    • disaster recovery capabilities (reduces RTO and RPO),
    • scale read operations into a region closer to end users,
    • migration from a data center in one region to another region

Cross-Region Read Replicas

RDS Cross-Region Read Replicas Process

  • RDS configures the source DB instance as a replication source and setups the specified read replica in the destination AWS Region.
  • RDS creates an automated DB snapshot of the source DB instance in the source AWS Region.
  • RDS begins a cross-Region snapshot copy for the initial data transfer.
  • RDS then uses the copied DB snapshot for the initial data load on the read replica. When the load is complete the DB snapshot copy is deleted.
  • RDS starts by replicating the changes made to the source instance since the start of the create read replica operation.

RDS Cross-Region Read Replicas Considerations

  • A source DB instance can have cross-region read replicas in multiple AWS Regions.
  • Replica lags are higher for Cross-region replicas. This lag time comes from the longer network channels between regional data centers.
  • RDS can’t guarantee more than five cross-region read replica instances, due to the limit on the number of access control list (ACL) entries for a VPC
  • Read Replica uses the default DB parameter group and DB option group for the specified DB engine when configured from AWS console.
  • Read Replica uses the default security group.
  • Cross-Region RDS read replica can be created from a source RDS DB instance that is not a read replica of another RDS DB instance for Microsoft SQL Server, Oracle, and PostgreSQL DB instances. This limitation doesn’t apply to MariaDB and MySQL DB instances.
  • Deleting the source for a cross-region read replica will result in
    • read replica promotion for MariaDB, MySQL, and Oracle DB instances
    • no read replica promotion for PostgreSQL DB instances and the replication status of the read replica is set to terminated.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. Your company has HQ in Tokyo and branch offices worldwide and is using logistics software with a multi-regional deployment on AWS in Japan, Europe, and US. The logistic software has a 3-tier architecture and uses MySQL 5.6 for data persistence. Each region has deployed its database. In the HQ region, you run an hourly batch process reading data from every region to compute cross-regional reports that are sent by email to all offices this batch process must be completed as fast as possible to optimize logistics quickly. How do you build the database architecture to meet the requirements?
    1. For each regional deployment, use RDS MySQL with a master in the region and a read replica in the HQ region
    2. For each regional deployment, use MySQL on EC2 with a master in the region and send hourly EBS snapshots to the HQ region
    3. For each regional deployment, use RDS MySQL with a master in the region and send hourly RDS snapshots to the HQ region
    4. For each regional deployment, use MySQL on EC2 with a master in the region and use S3 to copy data files hourly to the HQ region

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.