Highly available means the system remains operational with minimal downtime, even during failures. It uses redundancy, failover, and monitoring to ensure uptime.
Configuring your app with appropriate TTL is always followed after Configuring Multi AZ deployment
HA vs Scalable
- Scaling handles load increases (horizontal/vertical).
- High availability ensures uptime.
Backups do not make the architecture highly available. Backups are for data recovery (disaster recovery, data loss). Backups help with durability, not availability.
How applications should handle RDS failover in case of AZ failure
- Set low DNS cache TTL
- Enable TCP retry logic in app
- Use the RDS endpoint (not IP)
how to create a multi az deployment
- At the time of creating
- Conver exiting DB instance to multi az by modifiying the DB instance