AWS Database

RDS[2]#

Multi-AZ Deployments	Read Replicas
Synchronous replication – highly durable	Asynchronous replication – highly scalable
Only database engine on primary instance is active	All read replicas are accessible and can be used for read scaling
Automated backups are taken from standby	No backups configured by default
Always span two Availability Zones within a single Region	Can be within an Availability Zone, Cross-AZ, or Cross-Region
Database engine version upgrades happen on primary	Database engine version upgrade is independent from source instance
Automatic failover to standby when a problem is detected	Can be manually promoted to a standalone database instance

1
2
3

注：
RPO = Recovery Point Objective
RT0 - Recovery Time Objective

Replicas
- Aurora Replicas are within a region
- Replicas scale-out read requests
- Can promote Aurora Replica to be a new primary or create new primary
- Can use Auto Scaling to add replicas
Cross-Region Replica with Aurora MySQL
- Asynchronous replication
  Replication uses the MySQL database engine
Global Database
- Replication uses the Aurora storage layer
- Applications can connect to the cluster Reader Endpoint [3]
Fault Tolerance
- Fault tolerance across 3 AZs
Multi-Master
- All nodes allow reads/writes
- Available for MySQL only
- Up to four read/write nodes
- Single Region only