RDS Multi-AZ

Configuration

Both RDS instances have Multi-AZ enabled, providing synchronous replication and automatic failover.

Database	Engine	Multi-AZ	Failover Time
prod-nhc-django	MySQL 8.0	✅	~60-120 seconds
prod-nhc-wpcms	MariaDB 10.11	✅	~60-120 seconds

How It Works

1. AWS maintains a synchronous standby replica in a different AZ
2. On failure (hardware, AZ outage, network), AWS automatically updates the DNS endpoint
3. Applications reconnect via the same RDS endpoint — no config changes needed

Failover Triggers

• Primary instance hardware failure
• AZ outage
• Manual failover (for maintenance)
• OS patching on the primary

Testing Failover

aws rds reboot-db-instance \
  --db-instance-identifier prod-nhc-django \
  --force-failover \
  --profile 794248400165_AdministratorAccess

Warning

This causes ~60-120 seconds of downtime. Test during maintenance windows only.